This PDF file contains the front matter associated with SPIE Proceedings Volume 7493, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

This paper presents a trailing edge flap actuation mechanism using a novel pre-stressed piezoelectric unimorph, PUMPS (Piezoelectric Unimorph with Mechanically Pre-stressed Substrate). Experimental evaluation of actuation performance such as force-displacement characteristics of PUMPS actuators showed that the performance of PUMPS satisfied the requirements for trailing edge flap actuation. Subsequently, flap actuation mechanisms were designed and constructed with several slot types in the flaps, and stacked PUMPS actuators were applied to the flap actuation mechanisms. Experimental study of the test wing models with four flaps was accomplished, and the flap angle was achieved up to ±5.5° within 15Hz under maximum applicable voltage.

This paper presents a finite element procedure for modeling beam bimorph piezoelectric power harvesters including viscoelasticity. A three node beam finite element is employed to model the longitudinal and flexural response of the piezoelectric structure carrying an offset proof mass. Within a beam finite element, the proposed element permits a quintic polynomial shape function for lateral deformations and a quadratic polynomial shape function for the longitudinal deformation. The dynamic equations of the electromechanical system are established using the Lagrange equations method and solved for harmonic base motions. A series of experiments were carried out to quantify the visco-elasticity constant of a piezoelectric structure and validate the simulation results. Excellent agreement was observed between the measurement and simulation data for a range of operating parameter.

A new conductive rubber composite was fabricated by mixing the ruthenium oxide nanoparticles with silicone rubber. The ruthenium oxide nanoparticles were synthesized by oxidation of metallic ruthenium nanoparticles, which were made using a polyol method. The size of the ruthenium oxide can be tuned by changing the annealing duration in inert atmosphere. It was found that the composite filled with ruthenium oxide of the less size presents more stable piezoresistance recurrence. Based on the random resistor network model and transfer matrix approach, a numerical calculation of the tunneling bonds resistor lattice was conducted to simulate the percolation and piezoresistance behavior of the composite. The simulation shows that the particle size and distribution have strong influences on both the percolative conductivity and the piezoresistance sensitivity.

Circular piezoelectric bimorph has been successfully used in numerous types of microdevices, such as actuators for flowcontrol applications, transducers for acoustic applications, and in locomotion of robotic systems, energy harvesting and active structural health monitoring applications. Recently, the concept of the functionally graded material (FGM) is introduced to improve properties and increase lifetime by selectively grading the elastic, piezoelectric, and/or dielectric properties along the thickness of a piezoceramic. However, even for the simple case of homogeneous circular piezoelectric geometry, analytical treatments are severely limited. This study established an axisymmetric and isoparametric graded element to model the functionally graded circular piezoelectric plates. All the material properties including elastic coefficients, piezoelectric coefficients, dielectric parameters and mass density are graded in the element and interpolated using the shape functions, which is also used to render the displacements and electric potential distribution in the element. Both static and dynamic cases can be considered in this element. MATLAB is used to implement the whole FEM code and gives some numerical examples to demonstrate the presented method.

Acoustic performance of regenerated cellulose electroactive paper (EAPap) as a thin flexible film speaker was investigated. The enhancement of piezoelectric properties was obtained by a simple mechanical stretching process. As a prototype of flexible paper speaker, the sound pressure level (SPL) of cellulose EAPap film was evaluated as a function of distance, speaker size and geometry. It was revealed that the higher acoustic output from a small rectangular shape in low frequency range, while circular one seems to be better than that of all rectangular type speakers in audible frequencies.

Piezoelectric rods are frequently used as transformer, known as Rosen transformer. This paper shows that the equations of motion governing the free longitudinal vibration of a nonuniform piezoelectric rod, for two special variations of crosssectional area, can be reduced to those that can be solved analytically by using suitable variable substitutions. Exact analytical solutions to determine the longitudinal natural frequencies and mode shapes for the nonuniform rod are derived. Numerical examples are given to show the effect of geometric non-uniformity on the dynamic characteristics of the rod.

A poly (acrylic acid)-titanium oxide (PAA-TiO2) was successfully prepared and verified by particle size distribution analyzer and transmission electron microscopy. The fabrication of self-assembly films from diazoresin and PAA-TiO₂ was confirmed by UV-vis measurement. Thickness of the films was regularly increased with the layer-by-layer selfassembly process. Furthermore, the ionic bonds in the polymer films converted to covalent bonds under UV irradiation, with the decomposition of diazoresin group. Finally, the surface morphology of the films was investigated by atomic force microscopy (AFM). Results indicate TiO₂ were uniformly dispersed in thin films by the self-assembly process.

Microstructures and mechanical properties of zinc oxide (ZnO) thin films deposited onto glass substrates by rf magnetron sputtering were studied. Surface morphologies and crystalline structural characteristics were examined using atomic force microscopy (AFM) and X-ray diffraction (XRD), respectively. Mechanical properties were measured by nanoindentation. The crystalline structures of ZnO thin films were well ordered with high c-axis (002) orientations. The surface morphologies of ZnO thin films were smooth and grains grew and distributed uniformly. A single pop-in in the load-displacement curve was clearly observed at a specific depth (7-10nm) of the thin film. The hardness and Young's modulus of ZnO thin films were ranged from 8.2 to 10.4GPa and 105 to 120GPa, respectively.

The effect of microwave irradiation process on crystallization of Pb(Zr_xTi_1-x)O₃ (PZT) films was investigated. The PZT thin films were coated on Pt/Ti/SiO₂/Si substrates by a sol-gel method and then crystallized by single-mode 2.45 GHz microwave irradiation in the magnetic field at 500°C for 30 min and 650°C for 60 s, respectively. The crystalline phases, microstructures and electrical properties of the PZT films are investigated. X-ray diffraction analysis indicated that both the films heated by microwave irradiation at 500°C for 30 min and those at 650°C for 60 s were crystallized well into the perovskite phase. However, the PZT films crystallized at 500°C for 30 min had a (100)-preferred orientation while the PZT films crystallized at 650°C for 60 s had a (111)-preferred orientation. The average values of remanent polarization, coercive field, dielectric constant and loss of the PZT films crystallized at 500°C for 30 min are approximately 21 μC/cm², 90 kV/cm, 510 and 0.07 respectively, whereas the PZT films crystallized at 650°C for 60 s are approximately 27 μC/cm², 82 kV/cm, 900 and 0.05 respectively. The difference between the electrical properties of the PZT films crystallized by deferent process can be related to the microstructure effect.

The structural and gas sensing behaviour of metal oxides namely TiO₂ and ZnO thin films were investigated. In this paper, commercial Polyaniline (PANi) powder were added into two different metal oxides sol gel solutions with PANi : metal oxides weight ratios of 1wt.%, 2wt.% and 3wt.%. The thin films were fabricated using spin coating technique. Structural investigation using XRD presented that all films exhibited amorphous structure. Typical films surface morphology consists of agglomerated round shaped particles with the particles size varies between 57nm to 200nm. Addition of PANi formed network chains between the particles. Ethanol vapor detection test conducted at room temperature showed that both TiO₂ and ZnO based films were capable to sense the vapor. The optimum ratio in sensing ethanol vapour for both PANi-TiO₂ and PANi-ZnO films was 3:1. However, other issues such as reliability, selectability and repeatability remain as the major problems.

Health degradation by corrosion of steel in civil engineering is a persistent problem. Structural health monitoring techniques can lead to improve estimates of structural safety and serviceability effectively. The corrosion sensor and the monitoring method have been explored and applied in RC beam's corrosion monitoring. A novel five-electrode corrosion sensor has been developed to provide the platform for corrosion monitoring of the steel bar in concrete beam by electrochemical method. Half-cell potential of the RC beam has been measured to identify the corrosion statues of the steel bar qualitatively. Galvanostatic step method has been used to excite the steel-concrete system and the transient response of the system has been obtained. The data of the transient response has been analyzed by segmented method. Some important electrochemical parameters have been extracted by this method. The results show it is effectively to analyze the data of the transient response by segmented method.

The aim of the present work is to develop a system of smart devices that could be permanently attached on the surface of the structure for monitoring cracks in most aerospace structures in isolated environments. It is shown that temporal and spatial focusing can be achieved through synthetic time-reversal array method for a linear phase array of sensors and actuators. Numerical simulation verifies the convergence of piezoelectric phased array. Near-field and far-field radiation pattern are also investigated to get the ultrasound field convergence plot. The scanning precision can be adjusted by changing the size of the focus patch. A Piezoelectric phased array system performs a point-by-point scanning in which focusing allows the inspection of large areas. Damage to the structure can be inferred if there is a significant change in the transient response of the structure using the analysis of the amplitude of the received signal. The location of this damaged area can be determined using the analysis of the time it reaches the transducer. By the method of synthesis of received signal time delay from multiple sensors, we can considerably enhance the signal strength, thus reducing the negative effects of noises to solve the tough problem of processing the echo signal. The results suggest accuracy better than 1 mm in finding the location of crack tips.

In the field of fiber-optic sensing technology, distributed sensors that return a value of the measurand as a function of linear position along an optical fiber are regarded as a promising sensor which can be applied to structural health monitoring (SHM). We have developed a distributed strain sensing technique using long gauge fiber Bragg grating (FBG) based on optical frequency domain reflectometry (OFDR). FBGs functioning as mirrors with wavelengthselective reflectivity have been used as strain or temperature sensors. OFDR is a technique designed to measure backreflections from optical fiber networks and components. In our system, we use a longer gauge FBG whose length is ordinarily more than 100 mm and we can measure strain at an arbitrary position along the FBG. Therefore, we can obtain continuous strain data along the FBG. Furthermore, since the spatial resolution in strain measurements is less than 1 mm, it enables us to measure the strain distribution of stress concentrated area, such as welded and bonded joints, precisely. In this paper, we describe the principle of the distributed sensing technique based on OFDR and the applications to strain monitoring of a bonded joint and a wing box structure.

Composite pressure vessel with thin metal liner has the advantage of both composite and metal. Due to the difference of elastic strain limits of composite and metal, there is problem of the compatibility of deformation. Nine fiber Bragg gratings were bonded to the surface of longitudinal and hoop directions of pressure vessel to monitor the strain status during 4.5MPa service pressure condition. The measured strain by the Bragg sensor is perfectly linear with the applied force. However, the hoop strain decreased as loading process and increased as unloading process, it is also negative value on middle part of the dome. The phenomena had been discussed in this investigation. As a smart structure Bragg sensor can detect the real strain state of composite pressure vessel and is suitable for damage monitoring in service. Analyzing result shows the pressure vessel can work safely with the applied hydrostatic pressure.

1-3 cement-based piezoelectric composites that have good compatibility with concrete material have been developed for health monitoring of concrete structures. Transducers made of this type of composites have been especially designed to meet the requirement of being embedded into concrete materials. In the property calibration, the transducers show broadband frequency response which is the basic requirement of acoustic emission (AE) transducers. The frequency response of the transducers made of 1-3 cement-based composites and piezoelectric ceramic are compared. Plain concrete beams with embedded 1-3 cement-based piezoelectric transducers are prepared and tested. During loading, AE events are recorded. The accumulated AE event number is analyzed with the loading history. The damage evolution of concrete beam could be monitored using the system including embedded transducers and software to record and analyze the data.

In recent years, some innovative wireless sensing systems have been proposed. However, more exploration and research on wireless sensing systems are required before wireless systems can substitute for the traditional wire-based systems. In this paper, a new type of intelligent wireless sensing network is proposed for the heath monitoring of large-size structures. Hardware design of the new wireless sensing units is first studied. The wireless sensing unit mainly consists of functional modules of: sensing interface, signal conditioning, signal digitization, computational core, wireless communication and battery management. Then, software architecture of the unit is introduced. The sensing network has a two-level cluster-tree architecture with Zigbee communication protocol. Important issues such as power saving and fault tolerance are considered in the designs of the new wireless sensing units and sensing network. Each cluster head in the network is characterized by its computational capabilities that can be used to implement the computational methodologies of structural health monitoring; making the wireless sensing units and sensing network have "intelligent" characteristics. Primary tests on the measurement data collected by the wireless system are performed. The distributed computational capacity of the intelligent sensing network is also demonstrated. It is shown that the new type of intelligent wireless sensing network provides an efficient tool for structural health monitoring of large-size structures.

Debonding failure has been reported as the dominant failure mode for FRP strengthening in flexure. This paper explores a novel debonding monitoring method for FRP strengthened structures by means of OTDR-based fiber optic technology. Interface slip as a key factor in debonding failures will be measured through sensing optic fibers, which is instrumented in the interface between FRP and concrete in the direction perpendicular to the FRP filaments. Slip in the interface will induce power losses in the optic fiber signals at the intersection point of the FRP strip and the sensing optic fiber and the signal change will be detected through OTDR device. The FRP double shear tests and three-point bending tests were conducted to verify the effectiveness of the proposed monitoring method. It is found that the early bebonding can be detected before it causes the interface failure. The sensing optic fiber shows signal changes in the slip value at about 36~156 micrometer which is beyond sensing capacity of the conventional sensors. The tests results show that the proposed method is feasible in slip measurement with high sensitivity, and would be cost effective because of the low price of sensors used, which shows its potential of large-scale applications in civil infrastructures, especially for bridges.

Shape memory alloys (SMAs), when in the form of wires or short fibers, can be embedded into a host material to form SMA-composite for satisfying a wide variety of engineering requirements. Due to the weak interface strength between the SMA wire and the matrix, the interface debonding often happens when the SMA composites act by external force or actuation temperature or combination of them. It is, therefore, very important to understand the stress transfers between the SMA fibers and matrix and the distributions of internal stresses in the SMA composite in order to improve its properties. In this paper, a theoretical model incorporated with Brinson's constitutive law of SMA for the prediction of internal stresses has been successfully developed. The assumed stress functions which satisfy equilibrium equations in the fiber and matrix respectively and the principle of minimum complementary energy are utilized to analyze the internal stress distributions during fiber pull-out and/or thermal loading processes. The complete axisymmetric states of stresses in the SMA fiber and matrix have been developed. A finite element analysis has been also conducted to compare with the theoretical results.

Based on the dimensional analysis approach and finite element calculations, several scaling relationships in the indentation of super-elastic shape memory alloys with sharp conical indenter were obtained. These scaling relationships illustrate the dependence of the indentation response and the hardness on the material properties of shape memory alloys, such as the phase transformation and plastic deformation. In the finite element calculation, a newly developed constitutive model of super-elastic shape memory alloy including the plasticity of induced martensite phase was employed. It is shown that the yield stress and strain-hardening parameter of induced-martensite plays an important role in the indentation response besides the phase transition properties. Additionally, the general relationships between the indentation hardness and the phase transformation stress, maximum transformation strain, martensite yield stress, and strain-hardening parameter of shape memory alloys were obtained. The results show that the indentation hardness of shape memory alloys is not proportional to the phase transformation stress and martensite yield stress, and cannot be used directly to measure the phase transformation stress and yield stress of super-elastic shape memory alloys.

This paper describes an experimental study of the influence of thermal cycling at zero stress and the associated R-phase on two different training procedures for developing the two-way shape memory effect (TWSME) in shape memory alloys (SMAs). Two different sets of NiTi wire are used in the study: one set has been heat treated to ensure a transformation path with no R-phase, whereas the other set has had the same heat treatment which is then followed by repeated thermal cycling at zero stress to develop the R-phase. The study analyzes how both thermal cycling and the Rphase affect the transformation temperatures and the SMA hardness. Subsequently, two different TWSME trainings, thermal cycling under constant load and isothermal tensile deformation, are performed on each sample set. The study then analyzes the training procedures, the training parameters, the recoverable two-way strain and the transformation temperatures. The results show that after 30 thermal cycles, the SMA develops the R-phase and becomes harder. To obtain a substantial εtw together with a minimum plastic strain, the results suggest that the NiTi wire should be thermally cycled at zero stress prior to training until the R-phase is developed and trained by thermal cycling under constant load.

In this paper, a flexible Shape Memory Alloy (SMA) actuator based on Thermoelectric Module is presented. The proposed actuator is consist of a pre-shaped SMA wire at several located positions, and a two couples of Thermoelectric Modules (TEM), and some temperature sensors. This actuator is adopted the TEM as the driven mechanism, and it can drive the pre-shape SMA directly. Using this driven mode can directly control pre-location of the SMA actuator. Therefore the control flexibility of the actuator is greatly increased. This paper analyze of the differences and advantages between the TEM actuator and the traditional SMA actuators, and introduced the operational mechanism, structure and driven approach. The experimental results indicate that the actuator can make reciprocating motion smoothly and softly.

Taking advantages of the characteristics of super-elasticity and restoring forces while the shape memory alloy(SMA) wire (4.0mm in diamerer) was excited, concrete modal beams was established, and Ni-Ti SMA wire with different prestretching length and different quantity under martensitic state were embedded into the concrete tensile zone before the concrete casted under environmental temperature. The relationship between the resistance rate of SMA and the cracks width of beams was studied under loaded process, and the variety regulation of the cracks width of beam was reply while excited by electrifying. The impact of slip and bond between the concrete and SMA was taken into account (to prevent the slip of the SMA by embedding the anchors into both ends of the beam), while the process was simulated considering the influence of additional resistance coming from the anchor. The result agreed with the experiment well. It is shown that: the crack closed almost completely and the deformation recovered suddenly after the SMA was excited by electrifying; The drive effect can be improved by adding the quantity of SMA; If the cracks width of beam were less than 1.5mm, Clearly a linear relationship was between the rate of change alloy resistance and the rate of crack width of the concrete beam. The residual deformation of rebar played a very negative role in the recovering of the residual deformation.

The cast and electro-spun membranes of EVOH-g-nSPEG were prepared by solution cast method and electro-spun method respectively. The cast membrane Ionomer/Metal composites (IPMC) and electro-spun membrane IPMC were prepared by penetration-reduction process. The micro-morphology of these two IPMCs was studied by scanning electron microscope (SEM). The surface resistance (R_S) and critical response voltage (U_R) of IPMC electrode were tested and calculated by four electrode structure method and intercept method. And the bending stress of IPMC was tested by electro-deformation experiment. The results indicated that the surface of cast membrane IPMC had better smoothness and compactness than that of electro-spun one. The electro-spun membrane possessed compact surface and loose internal structure. The U_R for electro-spun membrane IPMC was lower than that of cast one. And the U_R for both IPMCs increased with the R_S increasing when tested with the same membrane structure and metal electrode. The cast membrane IPMC had higher bending stress with the maximum value being 4.75MPa while being only 0.66MPa for electro-spun membranes.

This paper proposes a conclusive scalable model for Ionic Polymer Metal Composites (IPMC) actuators and their interactions with mechanical systems and external loads. This dynamic, nonlinear model accurately predicts the displacement and force actuation in air for a large range of input voltages. The model addresses all the requirements of a useful design tool for IPMC actuators and is intended for robotic and bio-mimetic (artificial muscle) applications which operate at low frequencies. The response of the IPMC is modeled in three stages, (i) a nonlinear equivalent electrical circuit to predict the current drawn, (ii) an electro-mechanical coupling term, representing the conversion of ion flux to a stress generated in the polymer membrane and (iii) a mechanical beam model which includes an electrically induced torque for the polymer. Mechanical outputs are in the rotational coordinate system, 'tip angle' and 'torque output', to give more practical results for the design and simulation of mechanisms. Model parameters are obtained using the dynamic time response and results are presented demonstrating excellent correspondence between the model and experimental results. This newly developed model is a large step forward, aiding in the progression of IPMCs towards wide acceptance as replacements to traditional actuators.

Dielectric elastomer actuators (DEA) based on Maxwell-stress induced deformation are considered for many potential applications where high actuation strain and energy are required. However, the high electric field and voltage required to drive them limits some of the applications. The high driving field could be lowered by developing composite materials with high-electromechanical response. In this study, a sub-percolative approach for increasing the electromechanical response has been investigated. Composites with conductive carbon black (CB) particles introduced into a soft rubber matrix poly-(styrene-co-ethylene-co-butylene-co-styrene) (SEBS) were prepared by a drop-casting method. The resulting composites were characterized by dielectric spectroscopy, tensile tests, and for electric breakdown strength. The results showed a substantial increase of the relative permittivity at low volume percentages, thereby preserving the mechanical properties of the base soft polymer material. Young's modulus was found to increase with content of CB, however, due to the low volume percentages used, the composites still retain relatively low stiffness, as it is required to achieve high actuation strain. A serious drawback of the approach is the large decrease of the composite electric breakdown strength, due to the local enhancement in the electric field, such that breakdown events will occur at a lower macroscopic electric field.

Novel fullerene reinforced nano-composite transducers based on nafion were developed inorder to improve the ionic polymer metal composite transducer. The fullerene reinforced nano-composite membranes were fabricated by recasting method with 0.1 and 0.5 weight percentage of a Fullerenes. Stress-Strain tests showed tremendous increase in stiffness and modulus of the nano-composite membranes even at these minute concentrations of Fullerenes. Ionic exchange capacity analysis and proton conductivity test were performed to calculate the electrical property of the composite films. Water uptake was measured to understand the liquid adsorbing characteristics of the membranes. Also, tip displacement of the nano-composite membrane transducer was investigated under AC excitations with various magnitudes and frequencies. Furthermore, the generated energy was measured from external sinusoidal physical input vibration with several displacements and frequencies by using a mechanical shaker. As a result, the fullerene reinforced nanocomposite membrane based on nafion shows higher stiffness and Young's modulus than that of pure nafion membrane. Also, the nano-composite membrane had better water uptake and proton conductivity than the pure membrane. Fullerene reinforced nano-composite membrane transducer actuates to a much larger deformations than pure nafion membrane transducer. The developed membrane transducer dissipates more energy from the physical input vibration than that of unfilled(or virgin) Nafion membrane transducer.

The dielectric elastomer film will encounter electrical breaking-down frequently in its working state due to the coupling effect of electric field and mechanical force field. Referring to the electromechanical coupling system stability theory of dielectric elastomer proposed by Suo and Zhao, the electromechanical stability analysis of dielectric elastomer has been investigated. The free energy function of dielectric elastomer can be represented by the principle of superposition based on Suo's theory. Unstable domain of electromechanical coupling system of Neo-Hookean type silicone was analyzed by R. Díaz-Calleja et al. In the current work, the elastic strain energy function with two material constants was used to analyze the stable domain of electromechanical coupling system of Mooney-Rivlin type silicone, and the results seem to support R. Díaz-Calleja's theory. These results provide useful guidelines for the design and fabrication of actuators based on dielectric elastomer.

The influence of precipitations on the damping capacity of Fe-13Cr-2.5Mo (mass %) based alloys has been investigated in this paper. The damping behaviors were examined by dynamic mechanical analyzer (DMA) at temperature t = 35 °C, vibrate frequency f = 1 Hz and strain amplitude ε of 10^-6 and 10-3. Field-emission scanning electron microscope (FESEM) with X-ray energy dispersive spectrometer (EDS) was used to observe microstructure and determine the composition of precipitations. The results show that damping capacity of Fe-13Cr-2.5Mo based alloys is more strongly correlated with intragranular precipitation than with grain boundary (GB) precipitation. Fe-Cr-Mo alloy annealed at 1100 °C for 1 h followed by furnace cooling (FC) with relatively fewer intergranular precipitations, exhibits higher damping behavior. With the increase of annealing temperature, the amount of intragranular precipitations increases while damping capacity of Fe-Cr-Mo alloy decreases. Addition of 1.0% Ti obviously inhibits precipitation of GB precipitations, but promotes the intragranular precipitations in the alloy distinctly, so the damping capacity of Fe-Cr-Mo- 1Ti is slightly lower than that of Fe-Cr-Mo alloy. Addition of 1.0% Nb can significantly decrease damping capacity of Fe-Cr-Mo-1Nb at low strain amplitude. But at higher strain amplitude, damping capacity increases more rapidly and Fe- Cr-Mo-1Nb possesses the highest damping capacity. This result reveals that larger amount of precipitations in Fe-Cr-Mo based alloys can interact with dislocations and generate an amplitude-dependent dislocation damping Q^-1_dis at high strain amplitude.

Response time is an important parameter which determines the applied fields and practical vibration reduction effects of magnetorheological (MR) dampers. However, up to now, only a few papers discuss the test and analysis of response times. In this paper, the response time of a large-scale MR damper at different velocities and currents was firstly tested. Then, the transient magnetic field excited by the time-variant excitation current was simulated by finite element method (FEM). Based on the variation of the shear yield stress of magnetorheological fluids in the gap between the cylinder and the piston, the response time of the MR damper was investigated. Influences of eddy current and excitation current response time on the damper's response were also explored. Results show that by utilizing finite elements method, the calculated average effective shear yield strength can be used to predict the response time of a MR damper. Electromagnetic response is the predominant factor influencing the response time of a MR damper, and reducing eddy currents is the key to accelerate the response of a MR damper. Moreover, influence of eddy currents is much larger under stepping down excitation currents than stepping up currents, and with a same magnitude of step, no matter when the current increases or decreases, the smaller the initial current, the greater the eddy current affects a damper's response and the longer the response time of damping force is. A fast response excitation current may induce large eddy currents which reduce the response of the damper instead.

Magneto-rheological (MR) dampers, recently, have found many successful applications in civil engineering and numerous area of mechanical engineering. When an MR damper is to be used for vibration suppression, an inevitable problem is to determine the input voltage so as to gain the desired restoring force determined from the control law. This is the so-called inverse problem of MR dampers and is always an obstacle in the application of MR dampers to vibration control. It is extremely difficult to get the inverse model of MR damper because MR dampers are highly nonlinear and hysteretic. When identifying the inverse model of MR damper with simple fuzzy system, there maybe exists curse of dimensionality of fuzzy system. Therefore, it will take much more time, and even the inverse model may not be identifiable. The paper presents two-layer hierarchical fuzzy system, that is, two-layer hierarchical ANFIS to deal with the curse of dimensionality of the fuzzy identification of MR damper and to identify the inverse model of MR damper. Data used for training the model are generated from numerical simulation of nonlinear differential equations. The numerical simulation proves that the proposed hierarchical fuzzy system can model the inverse model of MR damper much more quickly than simple fuzzy system without any reduction of identification precision. Such hierarchical ANFIS shows the higher priority for the complicated system, and can also be used in system identification and system control for the complicated system.

In this paper, the multiple current flowing electromagnetic shunt damper was newly employed for the semi-active vibration suppression of the flexible structures. The electromagnetic shunt damper consists of a coil and a permanent magnet. The ends of the coil were connected to the multimode current flowing electromagnetic shunt circuit for vibration reduction of the cantilever beam employing energy dispersion method. The system was electro-magneto-mechanically coupled between the electrical circuit and mechanical vibrating cantilever beam with a electromagnetic transducer. The circuits were designed for first two mode control of the cantilever. The vibration and damping characteristics of the flexible beams with the electromagnetic shunt damper were investigated by tuning the circuit parameters. The effect of the magnetic intensity on the shunt damping was studied with the variation of the gap between the aluminum beam and the permanent magnet. The resistances of the shunt circuit were used to investigate vibration damping effect of cantilever. The theoretical prediction of frequency response of the beam under multiple mode electromagnetic shunt damping method has a good agreement with experimental results. Present results show that the magnet shunt damper can be successfully applied to reduce the vibration of the flexible structures.

Compared to the double-ended magnetorheological (MR) dampers, single-ended MR dampers are more suitable in limited-space required fields for their larger strokes. An accumulator is needed for a single-ended MR damper to balance the volume changes as the piston pulled out and back into the cylinder. Since an accumulator has a great influence on the damper's performances, this influence should be taken into account in the damper's designing procedure. In this paper, damping force formula is deduced for the single-ended MR damper with spring accumulator. Then both the method of determination main parameters of regular spring accumulator and its inherent drawbacks are presented. Finally, by utilizing the pseudoelastic character of shape memory alloy (SMA), a SMA spring accumulator is proposed and its design method is given as well.

Owing to their outstanding mechanical, tribological, electronic transport, chemical and biocompatibility properties, the ultrananocrystalline diamond (UNCD) films grown by the microwave plasma chemical vapor deposition method under hydrogen-poor conditions have become the subject of intense research interests over the past decade. Based on the available computational capabilities and experimental data, a combined kinetic Monte Carlo (KMC) and molecular dynamics (MD) procedure has been developed for large-scale atomistic simulation of the responses of polycrystalline UNCD films under various loading conditions. The mechanical responses of resulting UNCD film have been investigated by applying displacement-controlled loading in the MD simulation box. Recently, a systematic study is being performed to understand the combined effects of grain size, loading rate, temperature, imperfection, loading path and history on the material strengths and failure patterns of both pure and nitrogen-doped UNCD films. Furthermore, recent MD simulation results of the notch size effect on the failure mechanism of nano-scale hierarchical structures consisting of one-dimensional members arranged in parallel will also be discussed to better design MEMS devices.

Polyaniline nanotube was prepared with aid of lactic acid assembly. A chemical prototype sensor was constructed based on nanotube-structured polyaniline and two typical structured chemical sensors, one is an interdigital electrodes on flexible polymer substrate, the other is a highly sensitive quartz resonators. The gas-sensing behavior of the two typical sensors to some organic vapors operating at room temperature was investigated. Results showed rapid response, and good reversibility of these two typical sensors. The response time is 10-20 s, the reversible time is about 100 s. This study provides a simple approach for preparation of materials needed for a chemical sensor to selected organic volatiles with rapid response or organic flexible nanoelectronic devices.

Facility Management (FM) is a critical component of the operational phase of a building's life cycle, which includes management of building systems and its services. A large quantity of data is collected from maintaining a building through FM. One question that arises is how can this data be distributed between different systems? A solution to this problem is important for facility managers and maintenance staff. This paper discusses the merits of Radio Frequency Identification (RFID) technology and its potential use in applications within the FM sector. The paper also reports a prototypical demonstrator implementation of an RFID based information management system for FM-scenarios. The prototype was deployed and tested in an office room at University College Cork (UCC), Ireland. The applicability of RFID for Decentralised Information Management (DIM) was applied and specific results for demonstration outputs were achieved.

The photo-induced strain in transparent lead lanthanum zirconate titanate (PLZT) materials is due to a process of superposition of photovoltaic and converse piezoelectric effects. The photovoltaic effect in PLZT materials is observed only in the direction of spontaneous polarization of ferroelectric materials. In this paper, electrical and mechanical performance of PLZT ceramics polarized in 0-1 or 0-3 direction are investigated, and PLZT actuators and sensors with the 0-3 polarization are studied. For multilayer PLZT actuators, presented also are the formulas for the calculation of energy release rates due to debonding.

In ultrasonic nondestructive testing (NDT) of concrete structures, the synthetic aperture focusing technique (SAFT) can improve the resolution of target and therefore gives a better image display of the B-scan data. In traditional B-scan of concrete structures the ultrasonic transducers are usually moved manually to detect the whole structure, the detection speed and the consistency in different test points are greatly affected. A PZT sensor array is designed in this paper to perform B-scan on large concrete structures more efficiently. The excitation of the sensor array and the data processing techniques for the array data are discussed. A signal processing approach is proposed to improve the consistency between different test channels in the array. Experiments on real structures show the embedded objects can be located accurately by using the array sensor and SAFT method.

Guided wave based methods have shown great potential to practical use and have been the object of many researches for structural health monitoring (SHM). In this paper, a welded steel structure with rectangular section, which is almost 1:1 scale model for a bogie frame segment of train, is investigated by using both finite element method (FEM) and experimental analysis for the purpose of damage detection. Finite element models are established to simulate the propagation behavior of guided waves in the structure. An active actuator/sensor network is employed to generate guided waves propagating in the structures and collect response signals. Excitations at selected frequency are used to minimize the effect of the intrinsic multi-mode phenomenon of guided waves on the consequent signal interpretation. Modern signal processing approaches, such as continuous wavelet transform (CWT) and Hilbert transform (HT), are applied to all collected signals. An algorithm based on the concept of damage presence probability (DPP) is proposed for estimation of damage location. The results indicate that the recommended guided wave propagation based approach is reasonable for damage detection in such kind of structures.

Fiber Bragg gratings (FBGs) are capable of acquiring transient impact signals and are suitable for impact event monitoring and impact position locating. Previous application of this technique showed that the accuracy and the range within which the impact position can be located is limited. A detailed analysis concluded that the major cause of the above limitations was due to poor equipment resolution and angular insensitivity of the FBG. In order to minimize the number of FBGs deployed yet still maintains reasonable prediction accuracy and locating range, the sensitivity of the interrogation system has to be optimized. To identify a better technique to serve the above purpose, four different interrogating schemes have been compared in the current work. The configurations with an ASE light source modified by a commercial edge filter or an FBG are the least sensitive but remained stable under all impact conditions. In the other two configurations which comprise a ring laser scheme, the one with the sensing FBG being part of the laser ring is extremely sensitive and is capable of detecting the impact of a 70g projectile from a height of 0.1mm at a distance of 60cm. However, with increasing impact severity, the system may become unstable. The configuration where the sensing FBG is not part of the laser ring gives a good compromise between sensitivity and stability. Based on the above results, the implications on the sensitivities and limitations of the different configurations when used for impact event monitoring on large structures will be discussed.

Dielectric elastomers have received a great deal of attention recently for effectively transforming electrical energy to mechanical work. Their large strains and conformability make them enticing materials which can be applied in many domains: biomimetics, aerospace, mechanics, medicals, etc. In order to maximize actuator performance, the dielectric elastomer actuators should have a high dielectric constant and high dielectric breakdown strength. Here we have investigated the increase in permittivity of a commercial silicone elastomer by the addition of carbon nanotube. The percolation threshold of the composites is obtained to be low. Experimental results suggest that for the case of conductive filler particle-elastomer matrix interaction, actuation strain increases with increasing carbon nanotube content.

In this paper experimental results indicating the presents of hysteresis in the acrylic tape VHB 4910 produced by 3M are presented. It is shown that there are large stress relaxation times associated with this material making it difficult to separate viscoelastic effects and hysteresis. Additionally, a set of Preisach hysteresis models is presented and it is shown that these models fit the experimental results well. The simplest model having only 5 fitting parameters is suggested as the best model as the parameters can be uniquely determined, this not being the case for the other models.

Link-systems have been around for a long time and are still used to control motion in diverse applications such as automobiles, robots and industrial machinery. This study presents a procedure involving the use of a genetic algorithm for the optimal design of single four-bar link systems and a double four-bar link system used in diesel engine. We adopted the Successive Zooming Genetic Algorithm (SZGA), which has one of the most rapid convergence rates among global search algorithms. The results are verified by experiment and the Recurdyn dynamic motion analysis package. During the optimal design of single four-bar link systems, we found in the case of identical input/output (IO) angles that the initial and final configurations show certain symmetry. For the double link system, we introduced weighting factors for the multi-objective functions, which minimize the difference between output angles, providing balanced engine performance, as well as the difference between final output angle and the desired magnitudes of final output angle. We adopted a graphical method to select a proper ratio between the weighting factors.

In order to achieve the acquirement of flexible displayer, such as e-paper and touch screen, and to reduce the cost of conductive printing ink, the application of conductive polymer in printing ink is studied, and conductive flexible layer is acquired. The effect of N, N-dimethylformamide, glycerol, deionizer water, and pH value on the performance of water-based nano conductive polymer ink is studied by the second doping of conductive polymer nano suspension. The effect of various polymers on the conductivity of printing ink is researched by adding various polymer resins. At last, printing performance of the conductive polymer ink is tested by some printing methods, such as screen, and offset printing. Conductive printing layer which can be compared with the traditional conductive ink in the conductivity is acquired and the conductive layer is waterproof.

It has been the focus to develop low shrinkage dental composite resins in recent ten years. A major difficulty in developing low shrinkage dental materials is their deficiency in mechanical properties to clinical use. This paper reviews the present investigations of low shrinkage dental composite resins and attempts to develop a novel system with multifunctional POSS incorporated. In this paper, it is especially interesting to evaluate the influences of shrinkage with different weight percentage of POSS (0~15wt%) incorporated in dental composite resins. Their double bond conversions are evaluated and their microstructures are characterized with Fourier-transform infra-red spectroscopy and X-ray diffraction. Their mechanical properties are also presented in this paper. The results show that the shrinkage of nanocomposites with POSS can be reduced effectively from 3.53% to 2.18%. The mechanical properties of this novel system, such as strength, hardness and toughness, are also enhanced greatly. Especially with 2wt%POSS incorporated, the best integrative improved effects are revealed. The mechanism of shrinkage is discussed.

In this paper shape memory effect of shape memory composite in magnetic field was studied. The shape memory composite was filled by nickel powder, and the nickel powder was treated by silane coupling agent. The Tg of shape memory composite was measured by dynamic mechanical analyzer. The surface element of treated nickel powder was analysized with FT-IR. Furthermore, the dispersion of nickel powder in polymer was observed by SEM. The results indicated that the shape of composite filled by untreated nickel powder did not change in the magnetic field, while the composite filled by treated nickel powder was drawn in the magnetic field. The tensile stretch was decrease with the increase of nickel powder content in the shape memory composite. The addition of silane coupling agent onto nickel powder surface was helpful for the dispersion of nickel in polymer.

Wrinkling is a main factor affecting the performance of the membrane structures and is always considered to be a failure as it can cause dramatic decrease of shape accuracy. The study of membrane wrinkling control has the analytical and experimental meanings. In this paper, a feasible membrane shape control method is presented. An expression of wrinkle wavelength using stress extremum principle is established based on the tension field theory and the Von Karman large deflection formula which verifies the generation and evolution reason of membrane wrinkles. The control mechanism for membrane wrinkles is developed using shape memory alloy (SMA) and shape memory polymer composite (SMPC) actuators which are attached to the boundaries of the membrane for producing contraction/expansion forces to adjust the shape of the membrane. The whole control process is monitored by photogrammetric technique. Numerical simulations are also conducted using ANSYS finite element software with the nonlinear post-buckling analytical method. Both the experimental and numerical results show that the amplitudes of wrinkles are effectively controlled by SMA and SMPC actuators. The method introduced in this paper provides the foundation for shape control of the membrane wrinkling and is important to the future work on vibration control of space membrane structures.

A novel smart goggle with tunable light transmittance was designed, fabricated and characterized in this research. The developed smart goggle lens was all-plastic based electrochromic (EC) device. The working EC material was a layer of thin film conducting polymer: poly (3,4-(2,2-dimethylpropylenedioxy)thiophene) (PProDOT-Me₂), while the counter material of the device was a layer of thin film inorganic oxide: vanadium oxide-titanium oxide (V₂O₅-TiO₂) composite, which serves as an ion storage layer. A transparent electrolyte as the ion transport layer was sandwiched between the working and counter parts of the device. The whole device was sealed with an UV cured flexible film sealant. The smart goggle exhibited tunable light transmittance in visible light wavelength (380-800nm), with a maximum contrast ratio at 580nm. Meanwhile, other unique properties include fast switching speed, low driving voltage, memory function (no power needed after switching, bi-stable), great durability, high flexibility, light weight, and inexpensiveness.

A novel isolation seismic bearing model named the double-N SMA-rubber bearing was proposed and designed in this paper. The basic design idea was to add SMA wire bundles closed around the rubber bearing to improve the whole mechanical properties of the isolation seismic bearing. The corresponding theories equations and the working mechanism of this new isolation device were deduced. The application of this isolation model which was employed in the model shaking table test of a 1000m³ storage tank was presented. Different test working conditions and seismic excitations were given to analyze the structure response of the storage tank and the presented bearing properties. The presented bearing model was used in the first working condition. The displacement and acceleration responses of vertical tank model were obtained. Only the rubber bearing without SMA bundles was applied in another working condition. Meanwhile the structure response results were gained and contrasted with the former results. The experimental results show the presented isolation seismic model is effective in absorbing energy and can be used in the isolation seismic design of the vertical storage tanks.

An experimental study has been conducted to design and fabricate smart composite beams embedded with prestrained nitinol wire actuators. The fabrication process developed allowed both quasi-isotropic E-glass/epoxy and carbon/epoxy hosts to be eccentrically embedded with 10 parallel prestrained wires with a purpose-made alignment device and cured successfully in an autoclave. Smart composite beams of three different lengths were made for each type of host. Both single-cycle and multi-cycle thermomechanical bending actuations of these beams in the cantilever set-up were characterised experimentally by applying various levels of electric current to the nitinol wires. The performance characteristics showed that the present fabrication process was repeatable and reliable. While the end deflections of up to 41 mm were easily achieved from smart E-glass/epoxy beams, the limited end deflections were observed from the smart carbon/epoxy beams due primarily to our inability to insulate the nitinol wires. Moreover, it seemed necessary to overheat the prestrained wires to much higher temperatures beyond the complete reverse transformation in order to generate recovery stress.

During the past several strong earthquakes, most of the highway bridge suffered from unseating and pounding damage due to large displacement between the adjacent frames. One traditional approach for mitigating the unseating of the highway bridge is to use restrainers made of steel cables and rods. However, the elastic design demands of the restrainers will induce large additional forces on the structural components of the bridges. The aim of the study is to investigate the effects of the strong ground motions on the unseating and pounding damages of the base-isolated highway bridges, and the performance of the shape memory alloy (SMA) restrainers for the unseating reduction of the highway bridge. An analytical model of the highway bridge with SMA restrainers and pounding effects is established, and the performance of the SMA restrainer for eliminating the bridge unseating and pounding of the highway bridge is also analyzed. Numerical simulation results indicate that the pounding strongly increase the structural responses and the SMA restrainer can be effectively used to mitigate the bridge unseating and pounding damage when subjected to the strong ground motions.

For large civil engineering structures and base establishments, for example, bridges, super-high buildings, long-span space structures, offshore platforms and pipe systems of water & gas supply, their lives are up to a few decades or centuries. Damaged by environmental loads, fatigue effects, corrosion effects and material aging, these structures experience inevitably such side effects as damage accumulation, resistance reduction and even accidents. The traditional civil structure is a kind of passive one, whose performance and status are unpredictable to a great extent, but the informatics' introduction breaks a new path to obtain the status of the structure, thus it is an important research direction to evaluate and improve reliability of civil structures by the use of monitoring and health diagnosis technique, and this also assures the security of service for civil engineering structures. Smart material structure, originated from the aerospace sector, has been a research hotspot in civil engineering, medicine, shipping, and so on. For structural health monitoring of civil engineering, the research about high-performance sensing unit of smart material structure is very important, and this will possibly push further the development and application of monitoring and health diagnosis techniques. At present, piezoelectric materials are one of the most widely used sensing materials among the research of smart material structures. As one of the piezoelectric materials, PVDF(Polyvinylidene Fluoride)film is widely considered for the advantages of low cost, good mechanical ability, high sensibility, the ability of being easily placed and resistance of corrosion. However, only a few studies exit about building a mature monitoring system using PVDF. In this paper, for the sake of using PVDF for sensing unit for structural local monitoring of civil engineering, the strain sensing properties of PVDF are studied in detail. Firstly, the operating mechanism of PVDF is analyzed. Secondly, wireless collection system of PVDF is integrated with PVDF film, charge amplifier, wireless transceiver and the corresponding software. Then, with strain gauge as a reference, experiments have also been done to study the quasi-static and dynamic strain response of PVDF, such as sensitivity, linearity and frequency responding, etc. The experimental results show that PVDF is sensitive to the impact response of civil engineering structures, and can provide local monitoring in different frequency response cooperating with a strain gauge. The developed wireless collection system has the characteristics of no lines, saving cost and installation time, and thus further pushes the practical application of PVDF for civil engineering structures.

Reinforced concrete (RC) structure is one of most familiar engineering structure styles in the civil engineering community, which often suffer crack damage during their service life because of some factors such as overloading, excessive use, and bad environmental conditions. Thus early detection of crack damage is of special concern for RC structures. Piezoelectric materials have direct and converse piezoelectric effects and can serve as actuators or sensors. A health monitoring method based on PZT admittance signals is addressed in this paper, which use the electromechanical coupling property of piezoelectric materials. An experimental study on health monitoring of a RC beam is implemented based on the PZT admittance signals. In this experiment, the electrical admittances of distributed PZT sheets are measured when the host beams are suffering from variable loads. From the obtained PZT admittance curves one can find that the presence of incipient crack can be captured and the cracking load of the RC beam can also generally determined. By the experimental study it is concluded that the health monitoring technique is quite effective and sensitive for RC structures, which indicates its favorable application foreground in civil engineering field.

It is world widely concerned in the durability of reinforced concrete structures. Corrosion of rebar is one of the most important factors which can affect the durability of the concrete structures, and may result in damage to the structures in the form of expansion, cracking and eventually spalling of the cover concrete. In addition, the structural damage may be due to loss of bond between reinforcement and concrete and reduction of reinforcement cross-sectional area, and finally it may cause structure failure. With the advantages of linear reaction, small volume, high anti-erosion capability and automatic signal transmission, the smart sensors made of fiber bragg grating (FBG) to monitor strain, stress, temperature and local crack have got wide application in buildings, bridges and tunnels. FBG can be adhered to the surface of the structure, and also can be embedded into the inner of the structures when the project is being under construction to realize the real-time health monitoring. Based on volume expansion, the fiber bragg grating sensor for rebar corrosion is designed. The corrosion status of the structure can be obtained from the information provided by sensors. With the aid of the finite element software ANSYS, the simulation of the corrosion sensor was carried in this paper. The relationship between corrosion ratio and the shift of wavelength was established. According to the results of the simulation, there were differences between simulated results and measured results. The reason of the differences was also studied in this paper.

Based on the analysis of experiments, the damage of composite stitched foam-core sandwich structure under low-velocity impact has been studied in this paper. A numerical simulation is performed to predict the effects of stitching on the low-velocity impact response of stitched sandwich composite panels. The results of numerical simulation show that the damage areas of upper face sheet are greater than the lower one for both unstitched and stitched sandwich, however, the main patterns of damage are different. For the unstitched structure, the upper face sheet's damage is the main pattern of damage, whereas the crushing damage is the stitched one's main damage. The finite element results have corresponded well with the experimental results, which prove the correctness of the finite element model. The results indicate that stitching does not increase the load at which delamination begins to propagate, but greatly reduces the extent of delamination growth at the end of the impact event. Then, the damage areas' change has been taken into consideration as some factors change, those various factors include the impact energy, the thickness of upper panel, the thickness of foam core and the stitched density (stitched row spacing×needle spacing, suture thickness). And also it presents some related theoretical analysis.

Due to the complex nature of sandwich structures, development of the online structural health monitoring system to detect damages in honeycomb sandwich panels inherently imposes many challenges. In this study, the leaky guided wave propagation in the honeycomb sandwich structures generated by piezoelectric wafer actuators/sensors is first simulated numerically based on the finite element method (FEM). In the numerical model, the real geometry of the honeycomb core is considered. To accurately detect debonding in the honeycomb sandwich structures, signal processing based on continuous wavelet transform is adopted to filter out the unwanted noise in the leaky Lamb wave signals collected from the experimental testing. A correlation analysis between the benchmark signals at the normal condition and those recorded at the debonded condition is then performed to determine the differential features due to the presence of debonding. Finally, the image of the debonding is formed by using a probability analysis. Specifically, fusing images acquired from multi-frequency leaky Lamb waves are obtained to enhance the quality of the final image of the structure. The location and size of the debonding in the honeycomb sandwich structures are estimated quantitatively.

The unidirectional solidification equipment based on Bridgman method with high temperature gradient was designed, and the single crystal of Ti-50.0at%Ni alloy was successfully fabricated by this equipment as well as a selective growing zigzag-shaped crystallizer and a steady growth container that were made of electro graphite. The microstructure of single crystal sample was studied by means of Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS); the orientation of single crystal was measured by X-ray technology; the phase transformation points were determined by Differential Scanning Calorimetry (DSC). It is resulted that, the single crystal of TiNi shape memory alloy (SMA) can be prepared with a set of suitable process parameters; the microstructure of the single crystal obtained in this study is dendritic, there is Ti₂Ni intermetallic between the dendrites, the angle between the orientation of single crystal and [111] plane is about 15 degree; the shape memory performances are improved obviously and the maximum recoverable strain reaches 10%.

Nanoindentation is a good method for characterizing residual stresses with large gradient that distributed in a very confined area. In our previous research, a formula was brought out to characterize residual stresses from elastic modulus measured in nanoindentation experiments. In this paper, aluminum alloy bulks were used as samples to validate the formula. The bulks were machined to be mirror surface on one side through ultra-precision diamond turning. Two samples were compressed and stretched by load instruments respectively. Nanomechanical properties such as elastic modulus in the areas on the mirror surface of the compressed and stretched samples were both measured by a commercial nanomechanical test system (TriboIndenter, Hysitron Inc.). Using the formula, then, the mean values of residual stresses on the mirror surface were calculated through the acquired experiment data. After that, the two stressed samples were tested by a commercial XRD instrument (X'Pert, Philips Inc.). Comparing the residual stresses that obtained through nanoindentation and XRD methods, their difference was no more than 10.5%, which showed that the formula is suitable for characterizing residual stresses in materials even it has high plasticity. Thus, the formula was validated.

The snap-through dynamics of the bi-stable IPMC actuators were investigated to generate much larger displacements and periodical stable locomotion based on jumping phenomena according to boundary conditions. First, in the clamped-free BC, two curved cantilever IPMC actuators with a constant curvature and initial tip deflections of 8mm and 16mm were fabricated from flat IPMCs through thermal treatment under hot water simultaneously to reduce the residual stresses. A flat and two curved IPMC actuators were tested to evaluate the effect of initial shape in terms of step responses, harmonic responses and frequency response function tests under small and large deformation. The snap-through phenomena for the curved IPMC actuators unlike the flat IPMC actuator were observed with much larger tip displacements, low power consumption and periodical jumps of the instant velocity. Second, in case of all-clamped BC, the large and bistable responses were observed under DC and AC excitation through the end-shortening effect. These tests were conducted with various end-shortenings of 0.25, 0.5, and 1.0 mm. The jumping phenomena of IPMC actuator was remarkably observed at their conditions, respectively. Present results show that the initial curved deflection and endshortening of the IPMC actuator strongly affects the large deformation at respective boundary conditions due to the snapthrough phenomena.

The reduction of vibration in Aircraft/Aerospace structures as well as helicopter fuselage is becoming increasingly important. A traditional approach to vibration control uses passive techniques which are relatively large, costly and ineffective at low frequencies. Active Vibration Control (AVC), apart from having benefits in size, weight, volume and cost, efficiently attenuates low frequency vibration. Hitherto this was being achieved using high speed Digital Signal Processors (DSPs). But the throughput requirements of general purpose DSPs have increased very much and the Field Programmable Gate Arrays (FPGAs) have emerged as an alternative. The silicon resources of an FPGA lead to staggering performance gains i.e. they are 100 times faster than DSPs. In the present paper Active Vibration Control of a Composite Research Wing Model is investigated using Piezo electric patches as sensors and PZT bimorph actuators collocated on the bottom surface as secondary actuators. Attempt has been made to realize the State - of - the - Art Active Vibration Controller using the Xilinx System Generator on VIRTEX - 4 FPGA. The control has been achieved by implementing the Filtered-X Least Mean Square (FXLMS) based adaptive filter on the FPGA. Single channel real time control has been successfully implemented & tested on the composite research wing model.

The growth of Li_1+xMn₂O₄ via detonation reaction was investigated with respect to the presence of energetic precursors, such as the metallic nitrates and the degree of confinement of the explosive charge. The detonation products were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission electron microscopy were used to characterize the products. Li1+xMn2O4 with 1~2μm spherical morphology and more uniform secondary particles, but with smaller primary particles of diameters from 20 to 60 nm and a variety of morphologies were found. The oxides produced by this cheap method affirmed the validity of detonation synthesis of nano-size powders.

Vapor-grown carbon nanofibers (VGCNF) functionalized with amine-containing pendants, viz.H2N-VGCNF, reacted with 2,2-bis(phthalic anhydride)-1,1,1,3,3,3-hexafluoroisopropane, which was the dianhydride monomer used in in-situ polymerization with 1,3-bis(3-aminophenoxy)benzene to afford a series of CP2-polyimide nanocomposite films (FCNFCP2), containing 0.18-9.19 wt % of H2N-VGCNF (corresponding to 0.10-5.0 wt % of pristine VGCNF), via conventional poly(amic acid) precursor method. For comparison, another series of in situ nanocomposites containing pristine VGCNF (0.10-5.0 wt %) was also prepared similarly. While H2N-VGCNFs enabled direct formation of CP2 grafts on the nanofibers, pristine VGCNFs would result in a relatively weak interface between nanofibers and the CP2 matrix. Conducting-tip atomic force microscopy (C-AFM) showed that the electrical transport was solely through the nanofiber networks in the PCNF-CP2. In general, low-frequency ac impedance measurements followed well the percolation bond model with low percolation threshold; 0.24 and 0.68 vol % for PCNF-CP2 and FCNF-CP2, respectively. However, the design of interface is determined to be crucial for controlling the electrical behavior in four substantial ways: (i) magnitude of limiting conductivity, (ii) linearity of I-V response, (iii) magnitude and direction of temperature-dependent resistivity, and (iv) reproducibility of the absolute value of resistivity with thermal cycling. These observations are consistent with a direct CNF-CNF contact limiting transport in the PCNF-CP2 system, where the CP2 grafts on FCNF form a dielectric layer between individual CNFs, limiting transport within the FCNF-CP2 system. Furthermore, the CP2 grafts on the FCNF surface reduce local polymer dewetting at the nanofiber surfaces when the temperatures exceed the CP2 glass transition, and stabilize the structure of the percolation network and associated conductivity. The general behavior of these interfacial extremes (pristine and fully functionalized CNFs) set important bounds on the design of interface modification for CNFs when the intended use is for electrical performance at elevated temperatures or under extreme current loads. The influence of processing conditions resulting in the spread of measured conductivity by several orders of magnitude for films containing the same type and same amount of CNFs is also reported.

In this study, we used several molecular dynamic models to simulate the pull-out process of a carbon nanotube (CNT) that is assumed to be chemically connected to a carbon fiber, and to calculate the CNTs' geometry variation, displacement, energy and stress during this process. In the simulation, the CNTs' elongation and necking phenomena have been noted prior to the movement of the CNT's end embedded in resin. The simulation yields a CNT's plastic constitutive model in the pull-out process. The fracture resistance capability of a chemically connected CNT is then discussed. In the simulation of shearing, the prediction of the CNTs' capability of shear resistance has been conducted. Finally, by comparing the experiment result with the simulation, we predict the amido link break before the CNT pull-out in the shearing test.

The sweep-back effect of a flexible flapping wing is investigated through fluid-structure interaction analysis. The aeroelastic analysis is carried out by using an efficient fluid-structure interaction analysis tool, which is based on the modified strip theory and the flexible multibody dynamics. To investigate the sweep-back effect, the aeroelastic analysis is performed on various sweep-back wing models defined by sweep-chord ratio and sweep-span ratio, and then the sweep-back effect on the aerodynamic performance is discussed. The aeroelastic results of the sweep-back wing analysis clearly confirm that the sweep-back angle can help a flexible flapping wing to generate greater twisting motion, resulting in the aerodynamic improvement of thrust and input power for all flapping-axis angle regimes. The propulsive efficiency can also be increased by the sweep-back effect. The sweep angle of a flapping wing should be considered as an important design feature for artificial flexible flapping wings.

This paper describe a structural shape monitoring methodology based on modal transformation and strain sensing for morphing structures. There are four important components to this problem: constructing the displacement-strain relationship, modal identification, strain measurement and signal processing. These issues are addressed in this paper and a simple laboratory experiment was carried out, which shows there are still many challenges inherent in the problems.

Satellite mechanical performance is to be further enhanced e.g. by active launch vibration attenuation, and even more so by in-orbit micro-vibration and shape control and possibly also significant shape morphing. This puts stringent requirements on the actuators and their materials, such as high resolution of possibly large strokes, or a very broad operational temperature range going down to -150°C or even lower. The discussion also shows the need to consider the host material and structure together with the actuator as a highly interacting system. This holds to a considerable extent also for integrated fiber optic sensors used for strain and temperature monitoring.

Magnetorheological elastomers (MREs) are smart materials whose mechanical behavior can be tailored by external magnetic fields, showing promises for wide use in on-demand stiffness control applications. However, conventional MREs have comparatively inferior mechanical properties due to matrix materials. Meanwhile carbon nanotubes (CNTs) have proved to be excellent reinforcing fillers with increased stiffness, strain at failure, and damping performance for nanocomposites. In this project, synthesis and dynamic mechanical analysis are conducted for silicone-rubber-based magnetorheological nanocomposites embedded with multi-walled carbon nanotubes.

Energy harvesting has enabled new operational concepts in the growing field of wireless sensing. A novel energy harvesting device driven by aeroelastic flutter vibrations has been developed and could be used to complement existing environmental energy harvesters such as solar cells in wireless sensing applications. An analytical model of the mechanical, electromechanical, and aerodynamic systems suitable for designing aeroelastic energy harvesters for various flow applications are derived and presented. Wind tunnel testing was performed with a prototype energy harvester to characterize the power output and flutter frequency response of the device over its entire range of operating wind speeds. Finally, two wing geometries, a flat plate and a NACA 0012 airfoil were tested and compared.

For developing new marine non-toxic antifouling coating, it was investigated the luminescence property in seawater on long-life afterglow fluorescent coatings modified by nano-TiO₂. The influences of the content and crystalline microstructure of fluorescent powder, different binder resins of coating were studied on the luminescence characteristic of the coating. The results showed that fluorescent coatings modified by nano-TiO₂ represent the good luminescence characteristic in seawater. With the increase of the content of fluorescent and nano-TiO₂ powders in coating, the luminescence property of coating increases. As light afterglow time increases, the illuminance of both fluorescent powder and luminous coating decays exponentially. Compared with long-life afterglow fluorescent coatings not modified by nano-TiO₂, the afterglow illuminance of the coatings modified by nano-TiO₂ was remarkably improved. The luminescence property in seawater of the coating based on fluorocarbon resin is much more than that of the coating based on acrylate resin.

Molecularly imprinted polymers (MIPs) with excellent molecular recognition ability have been used in chemical sensors, chromatographic separation and biochemical analyses. Thymidine is an important part of DNA for biomolecular recognition and the intermediate of many medicines. The polymers imprinted with the template of thymidine and 5'-Otosylthymidine have been prepared, using a non-proton solvent, acetonitrile as the porogen. Direct imprinting with thymidine could not form strong molecular interaction sites in this system. Relative MIPs were obtained by bulk polymerization and their adsorption capacities were investigated. The adsorption capacities of MIP (P₂) and nonimprinted polymer (P₂₀) for thymidine are 0.120 mg•g^-1and 0.103 mg•g^-1, respectively. The imprinting factor is 1.17. As 5'-O-tosylthymidine is more soluble than thymidine moiety in acetonitrile and give rise to more sites of molecular recognition. The results demonstrated that the imprinted polymers were able to bind and recognize thymidine moderately in acetonitrile. MIPs imprinted with 5'-O-tosylthymidine like nature enzymes displayed some recognition ability to its analogues. The insoluble derivatives in the non-proton solvent can be an effective template to prepare efficient imprinting recognition sites.

In the current paper, a macroscopic differential model is constructed for the modeling of two-way shape memory effects in one-dimensional shape memory alloy (SMA) structures. The model is based on the phenomenological theory of thermoelastic phase transformations in SMAs. Hysteresis loops in both mechanical and thermal fields are treated as macroscopic illustrations of martensite transformations and martensite variant re-orientations. A non-convex free energy function is constructed such that each of its local equilibriums can be used to characterize one of the phases involved in the transformations. System states (strain) can be transformed upon external loadings (mechanical or thermal) from one stable equilibrium to another, thus the dynamics of phase transformations can be modeled by investigating the system state transformations. Governing equations for the transformation dynamics are formulated by employing the Lagrange's equation, and are expressed as nonlinear differential equations. Numerical examples of thermal and mechanical hysteresis loops associated with the transformations caused by thermal and mechanical loadings are presented. Two way shape memory effects and pseudo-elastic effects are successfully modeled.

This paper investigates the relationship between the functional fatigue level and the frequency response behaviour of NiTi Shape Memory Alloys. The specimens, which are SMAs with 0.7-millimeter diameter, were subjected to a constant stress under different number of thermal cycles, leading to different fatigue levels. The fatigue SMAs were tested in open-loop experiments with step inputs and sinusoidal inputs, and their frequency responses were evaluated as the magnitude and phase of the wires' displacement, with respect to the input voltage signal. The results of the experimental study showed that the dc gains of the specimens, subjected to ranges of stresses from 76 to 204 MPa, decreased as the fatigue levels of SMAs increased. Also, the differences between frequency responses of fatigue wires and those of healthy wire were noticeable over the frequency range up to the bandwidth of the wire, especially when the wires were loaded with lower stresses.

Shape memory alloys (SMAs) show strong hysteresis in stress-strain-temperature relations. The hysteretic behavior is mainly caused by the thermodynamic irreversibility during the thermoelastic martensitic transformation. The various types of stress-strain hysteresis observed for SMAs at different temperatures have been attributed to the martensitic reorientation (MR) and the stress-induced martensitic transformation (SIMT) processes occurred under loading. Based on such observations, a model is proposed to consist of two types of elements: MR elements and SIMT elements. The MR elements show only martensitic reorientation and the SIMT elements can behavior only according to the stressinduced martensitic transformation. A SMA sample is a proper combination, determined by two temperature dependent distribution functions, of these two types of elements in series, i.e. the stresses on the elements are identical and the strains sum up. Experiments are designed to determine the distribution functions and numerical simulations are performed to show the capability of the model in reproducing the stress-strain hysteresis of SMAs in the whole temperature range of applications

The space inflatable structures have received increasing attention in recent years. Inflatable boom is the fundamental structural part to help space inflatable structures maintain the expected configuration. In this paper, the methodology to control local wrinkle growth and the deformation configuration of the inflatable boom structure with Shape Memory Alloy (SMA) wires actuator is developed. The experimental equipment has been established to investigate the growth of wrinkling and the control abilities of SMA actuator, wavelength and amplitude parameters of the wrinkling deformation have been measured by non-contact deformation test system. To understand the behavior of an inflatable boom due to wrinkling, the boom structure is numerically modeled using the ANSYS FE program with the equivalent nodal force method. The recovery force generated by the SMA wires could remove wrinkling and restore the deformation of the inflatable boom. The results from the experiment and numerical analysis show that SMA wires can eliminate the wrinkling deformation of inflatable boom effectively.

This paper presents a study on the vibration characteristics of Ni-Ti wire inter-weaved glass fabric/epoxy composites. The Ni-Ti pseudo-elastic wires were used as warp yarns and embedded in the fabric preforms with various weaving methods. Dynamic Mechanical Analyzer (DMA) and vibration test technique were used to reveal the dynamical behaviors of specimens in different frequencies of vibration. The storage modulus E', the loss tanδ, the natural frequency f and damping ratio η were examined. The energy dissipation behaviors of the Ni-Ti pseudo-elastic wire, the geometry of textile fabric was also studied. The effect of weaving method on the vibration behavior in Shape Memory Alloy (SMA) based textile composites was considered. The results showed that: (I) the energy dissipation capacity of the wire could be significantly improved by increasing the tensile strain and speed, but slightly affected by loading frequency; (II) the woven of few Ni-Ti warps caused the increase of the storage modulus and the change of the loss tanδ. In the buckling vibration, the damping effects of Ni-Ti pseudo-elastic wires vary with the woven structures. The compact woven structure with proper Ni-Ti warp architectures would receive a small amplitude and good damping.

Based on real-time diagnosis of health status of reinforced concrete beam, intellectual supervisory layer of carbon fiber reinforced concrete (CFRC) was set up at the bottom of girder structure. The intrinsic law of tensile sensitive characteristic of CFRC was studied and the electrical property collection and the stress transformation system of structure intellectual layer were established. It depends on the premise that carbon fibers are conductive, and that a stable relationship between electric resistivity and stress field exists. The security self-diagnosis of girder structure was fulfilled through online real-time monitoring and evaluation on electrical signal of intelligence layer of reinforced concrete beam.

With the development of microelectromechanical system (MEMS) technology, the limitations of machining technology for silicon-based materials become more and more distinct. With its abilities on sub-micron structure machining, the pulsed laser micro-fabrication technology has an extensive application prospect in MEMS and many other materials. The thermal interaction process of polymer under laser irradiation is very complex, regularities on polymer target under laser irradiation between displacement and laser energy density can only be obtained through experiments. Based on finite element method (FEM), simulations have been performed and compared with experiment results. Relations among pulsed laser intensity, actuation duration and thermal shock loads were obtained from the comparison, and a formula for calculating the maximum ablation pressure of a carbon fiber epoxy resin polymer composites was proposed. This study provides theoretical basis to the pulsed laser micro-fabrication technology's application in the fields of MEMS.

Magnesium alloys have been increasingly used in the automobile, communication and aerospace industries due to their low density, high specific strength and good castability. Higher speed in vehicles, development in weaponry and high speed metal working all are characterized with high rates of loading. In current study, two magnesium alloys AZ91D and AM50 have been investigated at strain rates in the range between 300 s^-1 and 1250 s^-1. For AZ91D, the stress is first increased and than decreased with strain rate between 335/ s^-1 and 1175 s^-1. For AM50, a monotonic increase in the stress is observed with increasing strain rate from 438/ s^-1 to 1238 s^-1. The stress is much higher at higher strain rates than what is at quasi-static strain rate for both alloys. For nearly same strain rate, higher stresses are observed for AZ91D than AM50, although this difference is less at higher strain rates. The strain rate sensitivity of AZ91D first increased with increasing strain rate and than decreased. In case of AM50, the strain rate sensitivity has an overall increasing trend.

Epoxy resin and lead zirconate titanate (P-41) ceramic were respectively used as matrix and functional component to fabricate 1-3 and 1-3-2 connectivity piezoelectric ceramic-polymer composites by dice and filling method. The interface bonding condition between matrix and piezoelectric functional phase was investigated by using SEM. Piezoelectric properties, dielectric properties, electromechanical properties and acoustic impedance of the 1-3 and 1-3-2 connectivity piezoelectric composites were studied. The results show that the interface bonding of the two-phase materials is compact, comparing with the P-41 ceramic, the thickness electromechanical coupling coefficient K_t of both kinds of the composites is almost two times larger than that of P-41 ceramic, while the value of mechanical quality factor Q_m and dielectric loss tanδ are smaller, acoustic impedance Z and relative dielectric constant ε_r are almost half of P-41 ceramic. The value of d₃₃, g₃₃, K_t, Q_m, Z, ε_r, and tanδ of 1-3-2 connectivity piezoelectric composite are close to those of 1-3 connectivity piezoelectric composite, which show that the 1-3-2 connectivity piezoelectric composite can instead of 1-3 connectivity piezoelectric composite in special application field.

An exact elastodynamic solution is obtained for torsional vibration of a finite piezoelectric hollow cylinder subjected to dynamic shearing stress and time dependent electric potential at the internal surface. The cylinder is traction free at the two ends and is fixed at the external surface. The piezoelectric material belongs to 622 crystal class. In axial direction, the trigonometric series expansion technique is introduced to guarantee the solution satisfies the end conditions. Then the governing equations for new variables about the radial coordinate r and the time variable t are derived. By means of the normal mode expansion method, the solution for torsional vibration is finally obtained. Numerical investigations are presented and the dynamic behaviors of the finite piezoelectric hollow cylinder are analyzed.

The vibration frequency analysis of film bulk acoustic resonators (FBAR) is based on the assumption of layered infinite plates vibrating at a working mode, which can be the thickness-extension or thickness-shear depending on the choice of the mode. A transcendental equation is used to determine the vibration frequency with given materials and plate thicknesses. Similar to the analysis and design of quartz crystal resonators of thickness-shear type, frequency equations and displacements in films can be used for the calculation of resonator properties which are important for improvement and modeling. By expanding the formulation to include the piezoelectric effect, we shall also be able to obtain the electrical field as a vital addition to mechanical solutions. Of course, the piezoelectric effect will also be included in the solutions of frequency and displacements. The solutions can be used to calculate the electrical circuit parameters of a resonator. We study vibrations of layered FBAR structures for both thickness-extension and thickness-shear modes and the solutions also include the electrical field under an alternating voltage. With these equations, solutions, and further formulations on the electrical circuit properties of FBAR, we can establish a systematic procedure for the analysis and design, thus completing the currently empirical methodology in resonator development. These one-dimensional formulation based on the infinite plate assumption can be further improved through the consideration of finite plates and numerical solutions based on the commonly used finite element analysis. These studies will be the basis for the formulation and calculation of electrical circuit parameters that are highly demanded as FBAR technology is expanding quickly to other applications. The accurate analysis and resonator property extension will contribute to the sophistication of FBAR technology with improved design procedure and performance.

The study is describing Nylon yarn, though with low weight (specific weight 1.14), good elongation and high strength (4.5~9.5 g/d). Through the combination of irregular section long staple fiber to reach the core yarn, spun from Nylon fiber and long filament fiber, not only has the advantages of Nylon product but also has it can be used for making army-bag which can enhance the abrasion resistance, low weight and coving yarn that has doubled yarn effect from yarn surface consisting of Nylon fiber and long filament fiber. We used a Hamel's Elasto Twister (hollow-spindle machine) to prepare the yarn samples for our study. During spinning, the spindle speed was kept the same, while yarn through put speed was varied to obtain different wrap twists (700, 800, 900, 1000 T/M). The wrapping yarn is Nylon yarn with different count (40, 70D) and core yarn is ultra-high molecular weight polyethylene (UHMWPE) filament with 375 deniers, respectively. The results revealed the covered yarn have good physical properties and will be good performance in army-bag and army uniform. Keywords: Nylon, abrasion resistance, UHMWPE, physical properties

The silicon-based materials are widely used in MEMS. In this article, the thermal shock property of silicon-based materials under the multi-pulsed laser irradiation is studied and theoretical deduction under a relative numerical case is performed. Based on the non-Fourier conduction and the thermo-elastic theories, theoretical expressions between temperature and thermal stress of a silicon-based material under the multi-pulse heat flow are deduced; regularities among inner surplus temperature, time and depth in a silicon-based target and corresponding boundary are studied; further more, curves of inner thermal stress in cases of different relation time are obtained by using the finite difference method. As results indicated, under the multi-pulsed laser irradiation, the temperature curves present a delayed character in different section away from the boundary, which are closely connected with the relaxation time. In the non-Fourier theoretical solution, the front of the stress wave is very steep and presents an obvious thermal shock property. The conclusion may be helpful to the micro-fabrication technology in the fields of MEMS.

The time dependent degradation of first-stage blades for gas turbine was investigated. First, Two used blades were prepared from the operating facilities, and their operating hours were 25,000 and 52,000 hrs, respectively. Microstructural comparison of coating surfaces showed that exposure to the environment increased thickness of TGO (Thermally Grown Oxide) and β depletion region, and then debonding and spallation of TBC (Thermal Barrier Coating) occurred finally. In the case of substrate, Ni-based superalloy, the shape and size of γ' were changed with increasing operating time. Especially, in the leading and trailing edges of blades, the size of γ' was bigger and the shape was more elliptic than other region. It can be thought that the leading and trailing edges of blades can be the starting point of degradation in first-stage blades. Second, TBC failed blade used for 22,000 hrs was prepared and compared with other two blades. Large interfacial cracks were formed between top and bond coat, and TGO was not uniform and continuous. The chemical composition analysis on bond coat showed that low chromium content is responsible for the formation not only of Al oxide but also of Co, Cr, Ni oxides.

This paper reports the fabrication of organic solar cells using inkjet printing technique. The devices consist of an active layer sandwiched between ITO bottom electrode and aluminum as top electrode. The active layer is made of a blend of a fullerene derivative [6,6]-phenyl C61-butyric acid 3-ethylthiophene ester as acceptor and poly (3-octylthiophene-2, 5- diyl) (P3OT) as the donor. The ink of active layer was prepared with variation of donor and acceptor ratio 1:1 and 2:1by weight. The active layers were inkjet printed on ITO substrates layer by layer with variations of one, two and four layers. The performances of the devices were studied by observing the current-voltage characteristics of the device in dark and under illumination of 75 W/m² light. Most of the devices showed rectifier property in the dark and able to generate electrical current under illumination. The photovoltaic performance of the devices was found depending on the thickness and the donor- acceptor ratio of the active layers.

Embedding carbon nanotubes (CNTs) in load-bearing composite laminate hosts and thereby turning them into nanolaminates is a rapidly emerging field and has tremendous potential in enhancing mechanical performance of host laminates. This state-of-the-art review intends to provide physical insight into the understanding of enhancing mechanisms of processed and controlled CNTs in nano-laminates. It focuses on four aspects: (1) physical characteristics of CNTs including CNT length, diameter and weight percentage; (2) processing and control techniques of CNTs in fabrication of nano-laminates including distribution, dispersion and orientation controls of CNTs; (3) mechanical properties along with their testing methods including tension, in-plane compression, interlaminar shear (ILS), flexure, mode I and mode II fracture toughness as well as compression-after-impact (CAI); and (4) post-mortem microscopic corroborative evidence after mechanical testing. As this review indicates, selective and uniform production of CNTs with specific dimensions and physical properties has yet to be achieved on a consistent basis. There is little control over CNT orientations in most fabrication processes of nano-laminates except for some cases associated with chemical vapour deposition (CVD). There are only two reports on the in-plane compression and there is none on in-plane shear. For reinforcement-dominated mechanical properties such as tension and flexure, there is little enhancement as reported. However, substantial enhancement in in-plane compression strength was reported. For matrix-dominated mechanical properties such as ILS strength and mode-I and mode-II fracture toughness, significant enhancement, albeit with substantially varying degrees, has been reported. In the meanwhile, the lack of consistent characterisation in those properties was also noticeable. Post-mortem microscopic corroborative evidence was very limited.

The ductility of high strength concrete containing nano-TiO₂ were experimentally studied and compared with that of plain concrete and concrete containing silica fume by stress-strain relationship. The results showed that the ductility of high strength concrete containing nano-TiO₂ were better than that of plain concrete and concrete containing silica fume, which demonstrated that it is an available and effective way to improve ductility of high strength concrete by means of mixing nanophase materials into concrete. The origin of nano-particles improving ductility of high strengthen concrete was also preliminary interpreted.

The incorporation of multi-wall carbon nanotubes at weight fractions of 0.5% wt. and 1% wt. in a PRIMASET cyanate ester system (PT-30) was examined. The thermo-mechanical and electrical properties of the developed nanopolymers were investigated and were compared with the neat matrix properties. A preparation method was developed for the incorporation of the fillers in the resin system. The phenomenon of re-agglomeration of nanotubes took place in the first stages of curing schedule but nevertheless according to the SEM images a good dispersion was generally achieved. DSC, DMA, TGA and thermal conductivity tests were performed for the thermal characterization. For the electrical characterization, AC and DC measurements took place. No significant change in the glass transition temperature (Tg), thermal conductivity and mass loss values was observed in comparison with the neat resin systems. However, in both cases the improvement of electrical conductivity was about nine orders of magnitude, indicating that percolation had been achieved. The elastic modulus in bending was examined and a slight increase was observed in direct comparison with the neat resin. Finally, the developed doped nanopolymer was used as matrix for the CFRPs manufacturing. A full manufacturing protocol was developed in order to overcome the challenging issues concerning the cyanate esters' handling and manufacturing processes. Moreover AC and DC measurements were performed along with thermal conductivity measurements and TMA. The produced modified composites were tested for short beam strength.

This paper is intended to introduce the international adaptive aerostructures community to the tremendous opportunities these structures can bring to uninhabited aerospace systems. The paper starts with an overview of the most critical classes of adaptive aerostructures for uninhabited aerial vehicles (UAVs) and the materials which are used to drive them. The paper describes several classes of UAVs that take advantage of the various kinds of these technologies. Adaptive aerostructures are shown to be integrated into hovering, high speed, low speed and ultra-high performance UAVs. These ultra-high performance UAVs are shown to significantly benefit from newly invented Post-Buckled Precompressed (PBP) piezoelectric actuators. These UAVs are capable of hovering for extended periods of time as a helicopter in gusty, windy, dusty environments, then pop up, converting and dashing out like a missile at several hundred km/hr. The paper shows photos of ultra-high performance UAV launches from armored vehicles, a battle-damage assessment exercise and a live fire sequence with 40mm munitions. The paper concludes with a description of the Visual Signature Suppression (VSS) system which was employed on a 2m UAV operating at several hundred meters above ground level. The VSS system was shown to reduce the visual cross section to below 1.8cm² which is the threshold for human aircraft observation. Accordingly, the VSS equipped aircraft is said to "disappear" in mid flight.

As a novel bionic actuator, pneumatic artificial muscle has high power to weight ratio. In this paper, a variable camber wing with the pneumatic artificial muscle is developed. Firstly, the experimental setup to measure the static output force of pneumatic artificial muscle is designed. The relationship between the static output force and the air pressure is investigated. Experimental result shows the static output force of pneumatic artificial muscle decreases nonlinearly with increasing contraction ratio. Secondly, the finite element model of the variable camber wing is developed. Numerical results show that the tip displacement of the trailing-edge increases linearly with increasing external load and limited with the maximum static output force of pneumatic artificial muscles. Finally, the variable camber wing model is manufactured to validate the variable camber concept. Experimental result shows that the wing camber increases with increasing air pressure and that it compare very well with the FEM result.

In this paper, a novel kind of deployable morphing wing base on shape memory polymer (SMP) composite is designed and tested. While the deployment of the morphing wing still relies on the mechanisms to ensure the recovery force and the stability performance, the deploying process tends to be more steady and accurate by the application of SMP composite, which overcomes the inherent drawbacks of the traditional one, such as harmful impact to the flight balance, less accuracy during the deployment and complex mechanical masses. On the other hand, SMP composite is also designed as the wing's filler. During its shape recovery process, SMP composite stuffed in the wing helps to form an aerofoil for the wing and withstand the aerodynamic loads, leading to the compressed aerofoil recovering its original shape. To demonstrate the feasibility and the controllability of the designed deployable morphing wing, primary tests are also conducted, including the deploying speed of the morphing wing and SMP filler as the main testing aspects. Finally, Wing's deformation under the air loads is also analyzed by using the finite element method to validate the flight stability.

Ionic Polymer Metallic Composite (IPMC) is a smart material that can be used to make sensors for various applications. This paper investigates the use of IPMC for sensing the motion of a rotary joint. In this research, the relationship between the motion of a rotary joint and the IPMC sensor's voltage output was investigated and modeled. The relationships defining the sensor's response were developed into a routine which was used to calculate the bending angle and bending speed of a joint, based on the voltage response of an IPMC sensor. Experimental verification of the model produced results for measuring bending angles with an accuracy of within 3% across most of the range of angles. The accuracy of the measured bending speed was found to be related to the joint motion; with errors ranging from 0.4% at a slow bending speeds ( ≤150°s^-1) up to an error of ~8% at fast bending speeds ( ≥ 200°s^-1). Additional variables such as bending direction and starting position were also investigated to determine their effects on the sensor's response. It is concluded that the methods developed in this study provide a more complete description of the relationship between IPMC sensor voltage and joint motion than has previously been documented.

Nanoproducts spherical spinel lithium manganese oxide (LiMnO) with about 20nm in diameter was synthesized by explosive method. The growth of lithium manganate via detonation reaction was investigated with respect to the presence of an energetic precursor, such as the metallic nitrate and the degree of confinement of the explosive charge. The detonation products were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission electron microscopy were used to characterize the products. Lithium manganate with spherical morphology and more uniform secondary particles, with smaller primary particles of diameters from 10 to 30 nm and a variety of morphologies were found. Lithium manganate with a fine spherical morphology different from that of the normal spinel is formed after detonation wave treatment due to the very high quenching rate. It might also provide a cheap large-scale synthesis method. Explosive detonation is strongly nonequilibrium processes, generating a short duration of high pressure and high temperature. Free metal atoms are first released with the decomposition of explosives, and then theses metal and oxygen atoms are rearranged, coagulated and finally crystallized into lithium manganate during the expansion of detonation process.

This paper presents a two-phase imaging methodology to characterise damage in composite laminates utilising Lamb waves generated by integrated piezoceramic transducers. The proposed methodology uses the transducers to sequentially scan the composite laminates before and after the presence of damage by transmitting and receiving Lamb wave pulses. In phase one the damage localisation image is reconstructed by analysing the cross-correlation of the wavelet extracted information from scatter signals with the excitation pulse for each transducer pair. A potential damage area is then reconstructed by superimposing the image observed from each actuator and sensor signal path. In phase two Lamb wave diffraction tomography is used to reconstruct an image quantifying size and shape of the damage based on the same set of measurement data and identified damage location in phase one. The two-phase imaging approach together with the modified diffraction tomography reconstruction algorithm enables a significant reduction of the required number of transducers without the need to know the damage location in advance. Numerical and experimental results are presented to demonstrate the efficiency, accuracy and sensitivity of the proposed methodology.

A 1-3 type piezoelectric composite was fabricated by cut-filling technique. The effects of cement-polymer ratio on piezoelectric and dielectric properties of the composites were analyzed. The results show that piezoelectric strain factor d₃₃ and piezoelectric voltage factor g₃₃ exhibit the trend of decrease initially and then increase with increasing cement-polymer ratio. With the increase of cement-polymer ratio, the dielectric factor ε_r and dielectric loss tanδ of the composites increase initially and then decrease. Comparing with pure piezoelectric ceramic, the mechanical quality factor Q_m decreases obviously. Acoustic impedance Z is about 9 M raly, which is matching with concrete.

The magnetic nanoparticles with luminescent properties make the marker and separation work further convenient in the biological fields, such as bio-imaging, bio-labeling, bio-medicine, bio-treatment, etc. In the current research, a multifunctional nanoparticles with a magnetic Fe₃O₄ core and a CdTe quantum dots (QDs) shell of was prepared via self-assembling method and characterized via transmission electron microscopy (TEM), ultraviolet spectrum (UV), and fluorescence spectrum (FS). Magnetic Fe₃O₄ nanoparticles were firstly prepared by chemical precipitation method with sodium hydroxide as precipitant at 50°C, well dispersed Fe₃O₄ nanoparticles in size of 10 nm were observed via TEM and were use as core. The synthesized CdTe QDs were surface modified with 2-mercaptopropionic acid and the magnetic core-shell CdTe/Fe₃O₄ nanoparticles were constructed by the formation of electrovalent bond between -NH₃+ and -COO-. The prepared core-shell CdTe/Fe₃O₄ nanoparticles can be simply separated or precipitated from the reactant solution. The factors influencing the properties of nanoparticles were investigated, including mol ratio of Fe₃O₄:CdTe, refluxing time, reacting temperature, and pH value etc. The results indicated the core-shell CdTe/Fe₃O₄ nanoparticles with excellent magnetic and fluorescent properties can be achieved when the mol ratio of Fe₃O₄:CdTe is 1:3, and pH was set at 6.0, refluxed for 0.5h at 30 °C. 15nm of average size of the CdTe/Fe₃O₄ nanoparticles was confirmed with TEM. The red shift of maximum emission wavelength from 530 nm to 570 nm and maximum absorbance wavelength from 530 nm to 535 nm were determined via FS and UV, respectively, these data inferred the formation of CdTe shells. The core-shell magnetic and fluorescent CdTe/Fe₃O₄ nano-composites will be an useful tools in biological, genetics, and bio-pharmic applications.

The surface structures of Coscinodiscus granii frustules were investigated before and after liquid phase deposition (LPD) treatment. Scanning electron microscopy (SEM) images showed that the outer surface of the frustules was rapidly covered with a TiO₂ layer within 6 h although the inner surface was not fully covered under the same condition. Comparison between the un-coated samples and the samples coated with metal prior to SEM observation provided valuable results to facilitate the understanding of the differences between the surface properties of the inner and outer frustule structures. Additionally, useful topographical information about the inner frustule surfaces was obtained by AFM imaging. The results of this investigation provide fundamental information about the process of LPD treatment onto frustule surfaces.

A theoretical simulation is presented on the optical transmission and polarized extinction ratio through subwavelength wiregrid polarizer for GaN-based LED. The micro-polarizers are specially designed based on rigorous coupled wave analysis method for operation wavelengths of blue light (470nm) and green light (520nm) with metal wiregrid on the GaN substrate. The TM transmittance and the extinction ratio of TM and TE transmittances are influenced by period, thickness and duty cycle of the metal wiregrid. Aluminum and silver metal film grating under subwavelength is separately used for optimization design to improve the optical properties at the visible wavelengths. Simulation results show that, as the thickness of the metal grating decreases, the coupled light shifts the TM transmittance peak to shorter wavelength. As the same time, the extinction ratio remains a high value. TM transmittance coefficients separately greater than 95% and 97% with extinction ratio greater than 33dB are achieved for GaN-based aluminum grating and silver grating at the wavelength 470nm. And TM coefficients are greater than 92% and 96% with extinction ratios greater than 33dB, respectively at the wavelength 520nm. The thicknesses and periods of the metal grating are with sizes about 300nm, which are under subwavelength structures. The numerical results are useful for designing and fabricating novel photonic nanostructure polarized optical devices.

Due to the effect of marine environment, the corrosion of steel reinforcement in concrete structure is a very serious issue, so the field detection of steel reinforcement corrosion is very important. The Lianyun Harbor, a famous sea harbor in China with more than one hundred year history, was chosen to do the case study of the field detection. The corrosion ratio of the sampled steel reinforcement was obtained according to the field investigation in Lianyun Harbor and the experiment done in the laboratory. The chloride concentration in the concrete of different position and the sampled concrete at different depths in the splash zone was also measured in the laboratory. Moreover, the corrosive parameter of concrete structure was obtained by statistical analysis. The test results indicate that the reinforcement corrosion was very serious. The corrosion ratio of the sampled steel reinforcement and the concentration of chloride in concrete samples were both very high, which showed that Berth 14# in Lianyun Harbor was deteriorated badly. The chloride content at splash zone of Berth 57# and Berth 58# were also very high, which indicated that the chloride penetration for reinforcement concrete structures was very serious. The bearing capacity and the reliability of members could be calculated based on experiment data. The bearing capacity and the reliability of members decreased obviously and the members were needed to be maintained and strengthened in time.

The guided-wave-based damage detection techniques using structurally integrated Lead-zirconate-titanate (PZT) patches for structural health monitoring (SHM) have been developed for many years. However, the method is still in its formative years and one of the main challenges is the application in real-word complicated structures. It's very important to widely study the techniques in the structures with simple geometries which can be used to construct more complicated structures for practical applications. In this paper, different steel plates of the same dimensions were used for detecting a 2mm-gap through-crack in welded zone and studying the effects of different impurities such as water, alcohol, epoxy and mud in the crack on wave propagations. Advanced signal processing and pattern recognition techniques such as the wavelet transform (WT) especially continuous wavelet transform (CWT) and Hilbert transform (HT) were used to enhance the efficiency of damage detections in the steel plates. Some simulation results were obtained to validate of experimental results. The results from both the experiments and simulations show the validity of the proposed method and the effects of different factors on the damage detection of the steel plates.

To study the effect of different cross-section types on properties of carbon fibers, the microstructures of triangleshape carbon fibers and circle-shape carbon fibers were investigated by scanning electron microscope, X-Ray Photoelectron Spectroscopy and X-ray diffraction. The mechanical properties and electromagnetic properties of carbon fibers reinforced plastics were also studied. Results show that their microstructures and tensile-strength were similar, while the imaginary part of complex dielectric constant and loss tangent of the triangle-shape carbon fiber reinforced plastics are higher than those of the circle-shape carbon fiber reinforced plastics. The triangle-shape carbon fiber reinforced plastics have both the function of load bearing and the electromagnetic energy absorbing capability, and the composites will become promising radar absorbing structure material.

Shape memory polymer (SMP) has been applied in many fields as intelligent sensors and actuators. In order to improve the mechanical properties and recovery force of SMP, the addition of minor amounts of carbon nanotubes (CNT) into SMP has attracted wide attention. A micromechanical model and thermo-mechanical properties of CNT/SMP composites were studied in this paper. The thermo-mechanical constitutive relation of intellectual composites with isotropic and transversely isotropic CNT was obtained. Moreover, the shape memory effect of CNT/SMP composites and the effect of temperature and the volume fraction of CNT were discussed. The work shows that CNT/SMP composites exhibit excellent macroscopic thermo-mechanical properties and shape memory effect, while both of them can be affected remarkably by temperature and the microstructure parameters.

As a new class of smart material, shape memory polymer (SMP) receives more and more attention. In this paper, in addition to the fabrication of a new type of epoxy SMP, the thermo-mechanical properties of the polymer with/without gamma irradiation were investigated and compared systematically. The radiation source is Co-60 and the total dosage of radiation is 1×10⁴Gy. Changes of network structures of the polymer were investigated by Fourier Transform Infrared (FTIR) spectroscopy. The influence of gamma irradiation on thermo and mechanical properties of the polymer were investigated by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and tensile test, respectively. Furthermore, shape recovery behaviors of the polymer before/after the irradiation were compared too. Results show that the epoxy SMP possesses good chemical stability, glass transition temperature (T_g) determined by DSC decreased by 7°C after the irradiation. The gamma radiation has a slight influence on storage modulus, loss modulus and tan delta, respectively. No considerable change was found both in tensile strength and elongation at break after the gamma radiation. Finally, the shape recovery ratio of the polymer is near 100% with and without the gamma irradiation. Based on the above results, it can be demonstrated that the epoxy SMP prepared in the study possesses not only good thermo-mechanical properties but unique anti irradiation performance. The epoxy SMP shows potential for application of aerospace fields.

Impact-sliding wear of aluminum bronze against titanium alloy and 2Cr13 steel have been conducted using impactsliding wear test rig which was developed independently. Some non-destructive examinations have been performed on worn specimens, using weighing, 2D and 3D profilometry, scanning electron microscopy and EDS technology. Using laser scanning confocal microscope (LSCM), it has been found that the surface of aluminum bronze which wears against titanium alloy is much coarser than the surface which wears against 2Cr13 steel. Results of wear volume show clearly that although the hardness of titanium alloy has greater value than aluminum bronze, the wear volume of titanium alloy has much greater value compared with aluminum bronze. It has been found that there is remarkable material transferring from titanium alloy to aluminum bronze and little material transfer from aluminum bronze to titanium alloy. For the impact-sliding wear between aluminum bronze against 2Cr13 steel, the hardness of aluminum bronze has greater value than 2Cr13 steel, the wear volume of aluminum bronze has much greater value compared with 2Cr13 steel, whose wear volume can be ignored. Using EDS technology, it has been found that there is material transferring from aluminum bronze to 2Cr13 steel and material transferring from 2Cr13 steel to aluminum bronze can be ignored. Through the SEM pictures of worn surfaces and worn debris, flaking, particles and micro-cracks can be found on the worn surfaces. The wear mechanism of aluminum bronze against titanium alloy and 2Cr13 steel is delamination wear.

A kind of fiber Bragg grating displacement sensor using micro-elastic spring is proposed and studied in this paper. A type of micro-elastic spring was used as a displacement-wavelength conversion component. According to the sensor package design established, one micro FBG displacement sensor with outer diameter of 1.3mm was constructed. Tests were designed and conducted to study the displacement and temperature sensitivity of the sensor. Results show that there are good linear relationships between wavelength and displacement, as well as between wavelength and temperature. The displacement coefficient and temperature coefficient are 10.97pm/mm, and 21.38pm/°C, respectively. To obtain smaller displacement resolution of the sensor, one kind of sensitivity inhenced FBG displacement sensor is proposed and studied, the displacement coefficient is 110pm/mm.

A novel fiber Bragg grating (FBG) sensor system for Structure Health Monitoring (SHM) is proposed in this paper. The proposed sensor technique is based on time division multiplexing (TDM). This technique utilizes semiconductor optical amplifier (SOA) as a gain medium and switch. The SOA is driven by a pulse generator which switch on the SOA at different periods, as a switch to select the reflected pulses from a particular sensor. The FBG sensors have identical center wavelengths and can be deployed along the same fiber. This technique relieves the spectral bandwidth issue and permits the interrogation of up to 100 FBGs along a fiber. The sensor system has a fast signal process and control unit, which have a typical scan frequency in 50 Hz and self-adaptive measurement for simple sensor array installation.

The work presented herein has been focused on reinforcing the furfural resins (FA) by reactive-modified nanocrystalline cellulose (NCC) in an attempt to create a bio-nanocomposite completely based on natural resources. FA prepolymers were synthesized with an acid catalyst, and NCC was rendered reactive via the grafting of maleic anhydride (MAH). The resulting NCC and nanocomposites were characterized using TEM, SEM and FT-IR. It was found that NCC appeared to be spherical in shape with diameters under 100 nm. FT-IR confirmed that there were hydrogen and esterification bonding between MAH and NCC or FA prepolymer. After solidified with paratoluenesulfonic acid, NCC-reinforced FA resin composites showed granular cross-section while FA resin with layered structures. Mechanical property tests indicated that NCC-reinforced FA resin composites possessed the improved tensile and flexural strengths, in comparison with FA resin.

Fault diagnosis has been recognized as one of the key issues in wireless sensor networks. Considering distribution feature of sensor node, however, the fault happened in wireless sensor networks is usually random and unpredictable. The conventional diagnosis approaches become increasingly difficult to deal with. As a result, the application is limited seriously. To solve the problem, a new approach based on artificial immune system for fault diagnosis is proposed. The normal and abnormal character patterns generated by a network simulator for wireless sensor networks, respectively, are regarded as the self and antigen of artificial immune system. According to a real-valued negative selection algorithm, the detectors are generated to improve the covering ability of non-self space. Taking detector as antibody, an immunity calculation is executed by the distribution zones of antibody and evolution learning mechanism of artificial immune system. The type of antigen is decided based on the clustering distribution of cloned and matured antibody. The example shows that the approach has better accuracy and the capability of self-adaptive for the fault diagnosis in wireless sensor networks.

Advances in optic fiber sensing technology provide easy and reliable way for the vibration-based strain measurement of engineering structures. As a typical optic fiber sensing techniques with high accuracy and resolution, long-gauge Fiber Bragg Grating (FBG) sensors have been widely employed in health monitoring of civil engineering structures. Therefore, the development of macro strain-based identification methods is crucial for damage detection and structural condition evaluation. In the previous study by the authors, a damage detection algorithm for a beam structure with the direct use of vibration-based macro-strain measurement time history with neural networks had been proposed and validated with experimental measurements. In this paper, a damage locating and quantifying method was proposed using modal macrostrain vectors (MMSVs) which can be extracted from vibration induced macro-strain response measurement time series from long-gage FBG sensors. The performance of the proposed methodology for damage detection of a beam with different damage scenario was studied with numerical simulation firstly. Then, dynamic tests on a simply-supported steel beam with different damage scenarios were carried out and macro-strain measurements were employed to detect the damage severity. Results show that the proposed MMSV based structural identification and damage detection methodology can locate and identify the structural damage severity with acceptable accuracy.

Fiber Bragg Gratings (FBG) sensor is widely accepted as a structural stability device for all kinds of geomaterials by either embedding into or bonding onto the structures. The physical model in geotechnical engineering, which can accurately simulate the construction processes and the effects on the stability of underground caverns on basis of satisfying the similarity principles, is an actual physical entity. Due to a large number of restrained factors, a series of experiments are difficult to be carried out, in particular for how to obtain physical parameters during the experiments. Using the geo-mechanical model test of underground caverns in Shuangjiangkou Hydropower Station as a research object, the FBG sensors were mainly focused on and adopted to figure out the problem how to achieve the small displacements in the large-scale model test. The final experimental results show that the FBG sensor has higher measuring accuracy than other conventional sensors like strain gages and mini-extensometers. The experimental results agree well with the numerical simulation results. In the process of building the model, it's successful to embed the FBG sensors in the physical model through making a reserved pore and adding some special glue. In conclusion, FBG sensors can effectively measure the small displacement of monitoring points in the whole process of the geomechanical model test. The experimental results reveal the deformation and failure characteristics of the surrounding rock mass and make some guidance for the in-situ engineering construction.

Corrosion of rebar is one of the most important factors which can affect the durability of concrete structure, so in the service of these structures, measuring the degree of corrosion, and then evaluating the reliability of these structures are very important. The most significant characteristic of the rebar corrosion is its volume expansion. By the principle and characteristics of fiber bragg grating (FBG), a sensor for rebar corrosion is designed. In this paper, based upon laboratory studies, the fiber bragg grating sensor is applied in No.58 Berth of Lianyungang Port. According to the filed condition, a proper embedding scheme is proposed. Considering the optimal sensor placement, the monitoring points are determined and five sensor groups were applied in the structure. Based on the results of the calibration experiment, the relationship between corrosion ratio and the change of wavelength is established. So the corrosion status of the structure can be obtained by measuring wavelength. The study shows that the FBG sensor was feasible to monitor the status of rebar in concrete structures.

Research and development efforts are underway to provide structural health monitoring systems to ensure the integrity of thermal protection system (TPS). An improved analytical method was proposed to assess the fastener integrity of a bolted structure in this paper. A new unsymmetrical washer was designed and fabricated, taking full advantage of piezoelectric ceramics (PZT) to play both roles as actuators and sensors, and using energy as the only extracted feature to identify abnormality. This diagnostic method is not restricted by the materials of the bracket, panel and base structure of the TPS whose condition is under inspection. A series of experiments on a metallic honeycomb sandwich panel were completed to demonstrate the capability of detecting bolt loosening on the TPS structure. Studies showed that this method can be used not only to identify the location of loosened bolts rapidly, but also to estimate the torque level of loosening bolts. Since that energy is the only extracted feature used to detect bolt loosening in this method, the diagnostic process become very simple and swift without sacrificing the accuracy of the results.

Full-field measurement of dynamic stress has been realized by coating the surface of the test object metal with a upgrade mechanoluminescence sensing film of SrAl₂O₄:Eu (SAOE). Mechanoluminescent materials are attractive smart materials that can emit light induced by mechanical deformation. The ML sensing film of SAOE has been developed to make possible to visualize dynamic stress. Consequently this visualization technique has been become a promising experimental technique to investigate full-field stress analysis. In this paper we report the applications of the SAO ML sensing film for full-field stress analysis in aluminum alloy 5052 samples. Using the SAOE ML sensing film, the stress concentration produced by a circular hole was observed with the naked eyes in real time and the two-dimensional stress distribution was quantitatively measured; the complex and dynamic Portevin-Le Chatelier (PLC) effect, known as instability during plastic deformation, has been visualized, and the propagating characteristics of PLC bands were precisely investigated.

Dynamic mechanical analysis(DMA) tests are conducted on styrene-based fiber reinforced shape memory polymer (SMP) to investigate its glass transition behaviors. Results show the properties of stiffness, damping and energy dissipation of the reinforced SMP are obviously better than that of the pure SMP during the process of glass transition. Static threepoint bending tests are performed on the reinforced SMP to determine its stiffness and strength. Results show the reinforcement in the reinforced SMP improve the material properties of stiffness and strength at the room temperature. Cyclic three-point bending tests are operated to study the material training effect of the reinforced SMP. A training evolutional equation is established to describe the material training effect of the reinforced SMP. Numerical results show the training evolutional equation is able to predict the material training effect of the reinforced SMP effectively.

We have previously demonstrated that various types of patterns at different scales can be easily realized atop shape memory polymers (SMPs) through a procedure in three steps, namely, indentation, polishing and heating (IPH). On the other hand, by coating a thin metallic layer (e.g., a few nanometers thick of gold) atop SMPs with or without prestraining, different types of wrinkles could be generated. In this paper, we investigate the wrinkling patterns formed on the top of SMPs with a patterned surface, i.e., wrinkling atop a surface with a protrusion pattern. As the wrinkles are resulted simultaneously by two phenomena upon heating, namely the shape recovery of the SMP substrate and buckling of the elastic metallic layer, the wrinkle pattern varies from one location to another depending on the exact local strain. Utilizing this technique, we are able to simultaneously produce a surface with complicate surface patterns at both micro and millimeter levels. Such surfaces could significantly enhance many surface properties, e.g., bonding, adhesion and friction etc.

Shape memory polyurethane with different hard and soft segment based on aromatic diisocyanate (MDI) and polytetrahydrofuran (PTHF) or Polyethylene glycol (PEG) were synthesized by the prepolymer method. Glass transition temperature was tested by DSC. XRD results showed that the series of shape memory polyurethane has no crystallinity. And the shape memory behavior was also discussed. The results showed that the shape memory polyurethane made up of TMP-PTHF(1000)-MDI (2:1:5) performs better. It can recover 80% of original shape within one more second in the range of 37-45°C. SMPU films with PTHF as soft segment have good blood compatibility.

Identification of nonlinear dynamic systems using vibration measurements is crucial for efficient and reliable damage detection in structural health monitoring and control system design. Because of the complexity of control devices, it is usually difficult to model the nonlinear control devices with enough accuracy in a parametric form. In this study, a multi-storey steel-frame model structure equipped with magneto-rheological (MR) dampers, which were employed to introduce nonlinear phenomena to the model structure, was modeled with a neural network in a nonparametric way. Corresponding to the availability of dynamic response measurements, two different network models were proposed to predict the vibration response of the nonlinear model structure. Raw dynamic response measurements of the model structure under a certain impulse excitation was employed to train the two neural network models and the generality of the trained neural network models were validated in the form of forecasting the raw test dynamic response measurements of the model structure under other impulse excitation conditions. Results show that two neural network models provide a reliable way for the modeling of nonlinear dynamic structures and present a useful way for the control system design of engineering structures equipped with nonlinear control devices.

Phenol-formaldehyde resin is used as the most adhesive to produce waterproof plant-based composite. However, this product contains phenol and formaldehyde which can be easily released to pollute air and water. Based on the single-factor method, the effect of nano BaCO3 on situabtion of pyrolytic reaction of PF resin was studied by Py-GC/MS. There were components including carbon dioxide, D,.alpha.-tocopherol, 1,3-bis(trimethylsilyl) benzene, phenol from PF resin in 590(see manuscript) He gas. However, the 17 compounds including phenol, 2-methyl-, phenol, carbon dioxide, p-xylene, toluene, phenol, 2-ethyl-, phenol, 2,3-dimethyl-, benzene, 1,2,3-trimethyl-, etc were identified by Py-GC/MS after PF/BaCO3 composite was pyrolyzed in 590(see manuscript) He gas, and phenol and phenol derivants were found in the compounds. The result showed that nano BaCO3 could effectively delay the pyrolysis of PF resin.

This paper presents the reliability estimation studies based on structural health monitoring data for long span cable stayed bridges. The data collected by structural health monitoring system can be used to update the assumptions or probability models of random load effects, which would give potential for accurate reliability estimation. The reliability analysis is based on the estimated distribution for Dead, Live, Wind and Temperature Load effects. For the components with FBG strain sensors, the Dead, Live and unit Temperature Load effects can be determined by the strain measurements. For components without FBG strain sensors, the Dead and unit Temperature Load and Wind Load effects of the bridge can be evaluated by the finite element model, updated and calibrated by monitoring data. By applying measured truck loads and axle spacing data from weight in motion (WIM) system to the calibrated finite element model, the Live Load effects of components without FBG sensors can be generated. The stochastic process of Live Load effects can be described approximately by a Filtered Poisson Process and the extreme value distribution of Live Load effects can be calculated by Filtered Poisson Process theory. Then first order reliability method (FORM) is employed to estimate the reliability index of main components of the bridge (i.e. stiffening girder).

Damping in structures is commonly provided by viscoelastic nonstructural materials. Due to the large volume of structural materials in a structure, the contribution of a structural material to damping can be substantial. In this paper, the experimental investigation on damping ability of concrete materials and its members with Nana SiO₂ was carried out by the method of 3-point bending beam damping measurement and cantilever beam free vibration respectively. The microstructure of concrete mix with Nano SiO₂ was observed by XRD and SEM, then damping mechanism was discussed. The experimental results show that the damping reinforced effect achieved best with the 4% mixture ratio of Nana SiO₂, but the optimal adulteration quantity of Nano SiO₂ was 3% of cement weight by the comprehensive consideration of cost, workability, strength and dynamic properties. Nano materials as a mixture increase interfaces, and the non-uniform stress distribution under external force improves frictional damping energy consumption ability of concrete. The experimental results on the damping ratio and the loss tangent of the concrete materials with Nano materials are consistent.

To meet the need of long-term anticorrosive protection of steel, a heavy-duty anticorrosive coating systems was developed with Fluorocarbon top paint which was modified by nano-TiO₂. The corrosive characteristics of low carbon steel coated with the system were investigated in seawater by the exposition tests and Electrochemical Impedance Spectroscopy (EIS). The results show that the protective system with fluorocarbon top coating modified by nano-TiO₂ has much better endurance than the reference system with fluorocarbon top coating not modified by nano-TiO₂. There isn't any rusting and blistering on the surface of former coating, the coating system remains in "GOOD" condition. But some rusting and blistering were found on the surface of reference coating. EIS results indicated that the impedance of the nano-coating system decreases much less than that of the reference one. The nano-coating system is hopeful to meet the need of new coatings standard and to provide a target useful coating life of 15 years for ship's ballast.

Polymer composites are widely used in aerospace field, especially carbon fiber reinforced epoxy resin composites, because of the outstanding performance, became the most popular polymer matrix composites. However, the hygrothermal property of epoxy resin, as the matrix of the structure composite, is crucial to the whole composites. In this paper, the main focus is to modify the epoxy resin with nano-SiO₂ and nano-TiO₂ to enhance the hygrothermal property. Ultrasonic dispersion technology was used to prepare the nano-TiO₂ and nano-SiO₂ epoxy resin composites. The two kinds of composites were disposed in the climatic chamber for constant conditions. The effect of nano-particles on the hygrothermal property of epoxy resin composites were investigated by dynamic mechanics analysis (DMA) and mechanical properties testing. SEM images were taken to characterize the decentralization of the nano-particles in the composites. It is shown that nano-particles can be dispersed uniformly in the epoxy resin by ultrasonic dispersion. Thermo-analysis and mechanical testing results were presented that the epoxy nanocomposites has the excellent hygrothermal property under the same aging condition. Accordingly, the modified epoxy resin matrix can be used to prepare carbon fiber reinforced composites with remarkable hygrothermal property.

We employ a hydrodynamic theory for chiral liquid crystal polymers (CLCPs) to investigate the linear viscoelastic response of CLCPs to small amplitude oscillatory permeation shear flow, when the helix is oriented along the velocity direction and the orientation distortion retain the original planar structure. To predict the linear viscoelasticity, we model the system with Stokes hydrodynamic equations with viscous and nematic as well as cholesteric stresses coupled with orientational dynamics driven by the flow. The key findings are the following: in low frequency limit, both the loss modulus (G") and storage modulus (Gⁱ) exhibit a classical frequency ω dependence (G" ∝ ω, Gⁱ ∝ ω² ) but their magnitudes are of order O(q/Er^1/2 ), where 2π/q defines the pitch of the chiral liquid crystal and Er is the Ericksen number. In high frequency limit, Gi = O(q² /Er) is independent of ω while Gⁱ = O(1)ω is independent of q and Er.

This paper proposes applies MR fluid based suspension system to military vehicle for vibration control. The suspension system consists of gas spring and MR damper. In order to model of MR damper, a quasi-static modeling of the damper is conducted on the basis of Bingham model of MR fluid after describing the configuration and operating principle of the MR damper. And then the lumped parameter models of MR fluid flows in the damper are established and integrated to whole damper system by taking into account for dynamic motions of annular duct and gas chamber. Subsequently, a military vehicle of 6WD is adopted for the integration of the MR suspension system and its nonlinear dynamic model is established by considering vertical, pitch and roll motion. Then, a sky-hook controller associated with semi-active actuating condition is designed to reduce the imposed vibration. In order to demonstrate the effectiveness of the MR suspension system, computer simulation is undertaken showing vibration control performance such as roll angle and pitch angle. This is vibration control evaluated under bump and random road profiles.

Generally, a leakage in a high pressure hose assembly can be determined if hydraulic fluid falls down through fitting which is swaged with a rubber hose. This study tried to visualize leakage, which is considered a failure occurring often in the hydraulic system. In the case of methods which verify leakage paths in the power steering hydraulic system equipped with a high pressure hose assembly, three types of leakage paths, which could be seen by cutting the swaging part, were generally found. However, it was difficult to find out leakage paths by using power steering oil. In this study, four methods, including the thermal burn image method, the hole drilling method of fitting metal, the white paint infiltration method, and the fluorescent infiltration method, were tried to introduce. The thermal burn image method failed to find out the leakage path between the fitting part and the rubber part. The hole drilling method is the way to check a leakage path on the fitting part, which doesn't need to cut a hose assembly. This method succeeds to visualize the leakage path partially but it could not check a sequential path of leakage, either, because it needs to drill more closely. The white paint infiltration method also could find the leakage path partially by using white paint mixed with thinner, which was pressurized by hand pump, instead of power steering oil. This method could check the leakage path by cutting the swaging part. The fluorescent infiltration method could verify the leakage path with naked eyes simply by holding the cutting swaging part closely to the ray of light. Reappearance test methods in the high pressure hose assembly, which include a hole drilling, a white paint infiltration, and a fluorescent infiltration method, can be applied to find the failure mode and to approve the test before the mass production of the high pressure hose.

This paper describes the application of Neuro-Fuzzy techniques for controlling an IPMC cantilever configuration under water to improve tracking ability for an IPMC actuator. The controller was designed using an Adaptive Neuro-Fuzzy Controller (ANFC). The measured input data based including the tip-displacements and electrical signals have been recorded for generating the training in the ANFC. These data were used for training the ANFC to adjust the membership functions in the fuzzy control algorithm. The comparison between actual and reference values obtained from the ANFC gave satisfactory results, which showed that Adaptive Neuro-Fuzzy algorithm is reliable in controlling IPMC actuator. In addition, experimental results show that the ANFC performed better than the pure fuzzy controller (PFC). Present results show that the current adaptive neuro-fuzzy controller can be successfully applied to the real-time control of the ionic polymer metal composite actuator for which the performance degrades under long-term actuation.

Solid polymer electrolytes (SPEs) have attracted many attentions as solid state ionic conductors, because of their advantages such as high energy density, electrochemical stability, and easy processing. SPEs obtained from starch have attracted many attentions in recent years because of its abundant, renewable, low price, biodegradable and biocompatible. In addition, the efficient utilization of biodegradable polymers came from renewable sources is becoming increasingly important due to diminishing resources of fossil fuels as well as white pollution caused by undegradable plastics based on petroleum. So N, N-dimethylacetamide (DMAc) with certain concentration ranges of lithium chloride (LiCl) is used as plasticizers of cornstarch. Li⁺ can complexes with the carbonyl atoms of DMAc molecules to produce a macro-cation and leave the Cl^- free to hydrogen bond with the hydroxyl or carbonyl of starch. This competitive hydrogen bond formation serves to disrupt the intra- and intermolecular hydrogen bonding existed in starch. Therefore, melt extrusion process conditions are used to prepare conductive thermoplastic starch (TPS). The improvements of LiCl concentration increase the water absorption and conductance of TPS. The conductance of TPS containing 0.14 mol LiCl achieve to 10^-0.5 S cm^-1 with 18 wt% water content.

In this paper, carbon fiber reinforced plastic (CFRP) laminates (pristine and delaminated) are addressed for the purpose of damage assessment. Recently developed Doppler effect-based fiber optic (FOD) sensor was bonded on surface of each CFRP laminate to acquire piezoceramic-disc-excited guided waves propagating in the specimen. Characteristics of the captured guided wave signals were extracted by taking advantage of two well-developed signal processing algorithms, namely, linear-phase finite impulse response filter and Hilbert transform, so as to investigate the influence of the delaminations to the guided wave propagation. When guided waves are incident on discontinuities, mode conversion may occur as a result of satisfying the boundary conditions along the discontinuities. Both the dispersive characteristics of multi-mode guided waves and features of the guided-wave-generated fundamental shear horizontal (SH0) wave were applied for damage evaluation and multiple-damage detection. The results demonstrate that the FOD sensor is effective in multiple delamination detection for CFRP laminates because of its omnidirectional property in ultrasonic detection.

Bridge cables are used as critical structural components for cable-stayed bridges. It is essential to identify and monitoring the cable force of cable-stayed bridges in real time and continuously. In this paper, the design of a remote real-time cable force monitoring system including both hardware and software components are realized and the specifications of the system are also presented. The system was implemented in the Tianjin Yonghe cable-stayed bridge located in Tianjin, China, to remotely monitor the cable fore of the bridge and provide the condition assessment of the cables to the users via Internet. Experiences with this system demonstrate how effective low cost system provides a tremendous cost savings in terms of travel time, maintenance, and repair costs. This paper will also discuss the monitoring system and provides a preliminary analysis based on the data acquired from this system.

Fabrication of novel nanocomposite membranes comprising a fully sulfonated polyarylenethioether sulfone (SPTES) and sulfonated poly(p-phenylene benzobisimidazole)(SPBI) and the evaluation of the membrane properties are described. The nanocomposite membrane was obtained via a solvent cast process in a mixture of DMAc and methanol as solvents. The nanocomposite membrane proton conductivity, as measured by four probe impedance spectroscopy, was found to increase with increase in the SPTES content in the nanocomposite. The highest proton conductivity obtained was ~80mS/cm at 65ºC and 85 % relative humidity for the SPTES/SPBI 70/30 nanocomposite membrane which was considerably less than the 300 mS/cm for the pure SPTES membrane, but it was found that the swelling of the nanocomposite membranes was reduced due to the reduced water uptake of the nanocomposite membrane relative to SPTES. The morphology of the SPTES/SPBI nanocomposite membranes was examined by a combination of techniques, such as X-ray diffraction and scanning electron microscopy, to confirm the dispersion of SPBI in the nanocomposite. The membrane electrode assembly performance of the nanocomposite membranes was preliminary studied for H2/O2 fuel cells applications.

Ionic polymer metal composites (IPMC) are soft polymeric smart materials having large displacement at low voltage in moist environments or water. This type of actuators consists of an ionic membrane and noble metal electrodes plated on both surfaces. The ion-exchange membrane, Nafion, remains as the benchmark for a majority of research and development in IPMC technology. In this research, we employed sulfonated poly(styrene-ran-ethylene) (SPSE) that is crosslinked by UV irradiation as a novel ionic membrane. The crosslinking reaction between polymer matrix and crosslinking agent was proved by FTIR analysis. The sulfonic acid groups were stable during the UV irradiation crosslinking process. Water uptake, ion exchange capacity, and sulfonation degree are characterized for both pure SPSE and crosslinked SPSE membrane. The bending responses of SPSE actuators under both direct current (DC) and alternating current (AC) excitations were investigated. The voltage-current behaviors of the actuators under AC excitations are also measured. Results showed the crosslinked SPSE actuators have better electromechanical performance than that of pure SPSE actuator with regard to tip displacement.

In the family of smart material transducers, muscle-like transducers, i.e., dielectric elastomer transducers, have attracted much interest in recent years due to their many fascinating attributes such as large strain, fast response, high efficiency, simple, potentially low cost and light. The essential part of dielectric elastomer transducers is a dielectric membrane sandwiched between two compliant electrodes. Subject to a voltage, the dielectric membrane reduces its thickness and expands its area, converting electrical energy into mechanical energy. Due to large deformation, nonlinear equations of state, and diverse modes of failure, modeling the electro-mechanical response for dielectric elastomer transducers has been challenging. In this paper, the electro-mechanical behavior of a dielectric membrane deformed by the application of voltage and weight into an out-f-plane, axisymmetric shape is investigated. Ogden model is adopted to formulate the state equations by combining kinematics and thermodynamics. A set of ordinary differential equations characterizing the large out-of-plane deformation of the dielectric membrane are derived, and shooting method is applied to solving the equations numerically. The obtained results show that the field in the membrane is very inhomogeneous, which leads to most part of the membrane functioning inefficiently. This can be used to optimize the design of electromechanical transducers for specific applications.

Dielectric elastomers (DE) are one of the important electroactive polymers used as actuators in adaptive structures due to their outstanding abilities to generate very large deformations while subjected to an external electric filed. In this paper, Mooney-Rivlin elastic strain energy function with two material constants is applied to analyze the electromechanical stability performance of DE. This elastic strain energy couplied with the electric energy incorporating linear permittivity is the main item to construct the free energy of the system. Particular numerical results are also processing for further understanding of DE's typical stability performance. The proposed model offers great help in guiding the design and fabrication of actuators featuring DE.

In this study, a solution-phase method was demonstrated to generate silver (Ag) nanowires with diameters in the range of 30~50nm and lengths of up to ~50μm, which was proceed by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP). Fundamental material characterizations including X-ray diffraction transmission electro microscopy (TEM) and scanning electro microscopy (SEM) were conducted on these Ag nanowires. A novel kind of isotropical conductive adhesives (ICA) was prepared by using these Ag nanowires as conductive filler. Electrical property including bulk resistivity and mechanical property including shear strength were investigated and compared with that of conventional ICA filled with micrometer-sized Ag particles or nanometer-sized Ag particles. The average diameter of these Ag particles is about 1μm and 100 nm respectively. The results shown that ICA filled Ag nanowires exhibited higher conductivity, higher shear strength and low percolation threshold value than traditional ICA. Possible conductive mechanism was discussed based on theory calculation.

A type of calcium and titanium precipitation (CTP) material was synthesized by means of a simple co-precipitation method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and field emission scanning electron microscopy (FESEM) measurements were utilized to characterize the component, structure, and morphology of the CTP nanoparticles. The obtained particles were nano-scale and rod-like. The electrorheological (ER) measurement showed that the yield stress of the ER fluids reach about 146 KPa at a DC electric field of 5 KV/mm when the weight fraction is 67 wt%. It is substantially enhanced in comparison with the as-reported CTP ER fluids prepared by oxalate route. Furthermore, the ER fluids are very stable, environmentally friendly and attractive for large-scale utilization.