In this research, the capability of utilizing fluidic flexible matrix composites (F²MC) for autonomous structural tailoring is investigated. By taking advantages of the high anisotropy of flexible matrix composite (FMC) tubes and the high bulk modulus of the pressurizing fluid, significant changes in the effective modulus of elasticity can be achieved by controlling the inlet valve to the fluid filled F²MC structure. The variable modulus F²MC structure has the flexibility to easily deform when desired (open valve), possesses the high modulus required during loading conditions when deformation is not desired (closed valve - locked state), and has the adaptability to vary the modulus between the flexible/stiff states through control of the valve. In the current study, a closed-form, 3-dimensional, analytical model is developed to model the behavior of a single F²MC tube structure. Experiments are conducted to validate the proposed model. The test results show good agreement with the model predictions. A closed/open modulus ratio as high as 56 times is achieved experimentally thus far. With the validated model, an F²MC design space study is performed. It is found by tailoring the properties of the FMC tube and inner liner, a wide range of modulus and modulus ratios can be attained.

Adaptive control of electromagnetic (EM) properties across the surface of a platform can enhance its operational capabilities and survivability. Microfluidic systems may be an enabling technology for such EM control. Communication links use portions of the surface and other EM sensors may provide information about the environment or gather signal intelligence (SIGINT). At the surface, light or radar signals are reflected or scattered and provide the primary means of detection by an adversary's sensor systems such as radar. An electronically reconfigurable surface (ERS) would adaptively control these EM processes. An ERS is based on the distributed and adaptive control of the RF (radio frequencies) surface properties. For an ERS system the RF control would be accomplished by embedding in the surface region microwave circuits containing devices with controllable impedance characteristics. A microfluidic system that uses colloidal particle control and local circulation could provide a means of implementing the distributed impedance control needed for ERS systems. This paper provides a systems level overview of the application of microfluidic devices and systems as an enabling technology for ERS systems. A feedback and control subsystem would provide control signals to adaptively alter microfluidic device impedance characteristics, which would be the basis of the RF control.

Interface chemistry can be implemented to modulate the aggregation and dispersion of nanoparticles in a colloidal solution. In this experimental study, we demonstrate the controlled aggregation of superparamagnetic magnetite nanoparticles in organic and aqueous solutions. With decrease in solution pH, individual nanoparticles (12-14 nm) reproducibly cluster to form ~52 nm monodisperse aggregates in toluene. Spin-spin (T2) proton relaxation measurements of the micellated clusters before and after aggregation show a change in the molar relaxation rate from 303 sec^-1mol^-1 to 368 sec^-1mol^-1 for individual and clustered nanoparticles, respectively. DNA-mediated aggregation of micellated nanoparticles in the colloidal solution is also demonstrated where the number of single-stranded DNA per particle determines the ultimate size of the nanoparticle aggregate.

We have built a platform circulatory system by fabricating channels whose dimensions and layout are analogous to a fractal system where the reactants (fluids) are carried from a central reservoir, through progressively smaller channels ultimately with a width of 100 microns as they interface with the cellular structure. The construction of the macro/micro channel platform has been carried out using the direct write/solid freeform photo fabrication hybrid platform developed by the principle investigator. The interaction of reactants is controlled at the cellular level depending upon the fractional change in structural properties to be performed. The macro/micro channel system is metallized with copper, nickel and gold to enable to allow electrochemical transformations on demand. The circulatory system has been used to increase the modulus of a beam by polymerizing monomers to high modulus polymers with a view towards repairing structural damage. The metallized channels have been used to alter the electromagnetic absorption of a structure via electrochemical switching between conducting, semiconducting and insulating states. The electromagnetic characteristics have also been altered by replacing the dopant anions with anions of significantly altered stereoelectronic characteristics by taking advantage of the circulatory system.

In August of 2005 The Boeing Company conducted a full-scale flight test utilizing Shape Memory Alloy (SMA) actuators to morph an engine's fan exhaust to correlate exhaust geometry with jet noise reduction. The test was conducted on a 777-300ER with GE-115B engines. The presence of chevrons, serrated aerodynamic surfaces mounted at the trailing edge of the thrust reverser, have been shown to greatly reduce jet noise by encouraging advantageous mixing of the free, and fan streams. The morphing, or Variable Geometry Chevrons (VGC), utilized compact, light weight, and robust SMA actuators to morph the chevron shape to optimize the noise reduction or meet acoustic test objectives. The VGC system was designed for two modes of operation. The entirely autonomous operation utilized changes in the ambient temperature from take-off to cruise to activate the chevron shape change. It required no internal heaters, wiring, control system, or sensing. By design this provided one tip immersion at the warmer take-off temperatures to reduce community noise and another during the cooler cruise state for more efficient engine operation, i.e. reduced specific fuel consumption. For the flight tests a powered mode was added where internal heaters were used to individually control the VGC temperatures. This enabled us to vary the immersions and test a variety of chevron configurations. The flight test demonstrated the value of SMA actuators to solve a real world aerospace problem, validated that the technology could be safely integrated into the airplane's structure and flight system, and represented a large step forward in the realization of SMA actuators for production applications. In this paper the authors describe the development of the actuator system, the steps required to integrate the morphing structure into the thrust reverser, and the analysis and testing that was required to gain approval for flight. Issues related to material strength, thermal environment, vibration, electrical power, controls, data acquisition, and engine operability are discussed. Furthermore the authors layout a road map for the next stage of development of SMA aerospace actuators. A detailed look at the requirements and specifications that may define a production SMA actuator and the technology development required to meet them are presented. A path for meeting production requirements and achieving the next level of technology readiness for both autonomous and controlled SMA actuators is proposed. This path relies strongly on cross functional and organizational teaming including industry, academia, and government.

The actuation system of friction elements (such as band brakes) is essential for high quality operations in modern automotive automatic transmissions (in short, ATs). The current band brake actuation system consists of several hydraulic components, including the oil pump, the regulating valve and the control valves. In general, it has been recognized that the current AT band brake actuation system has many limitations. For example, the oil pump and valve body are relatively heavy and complex. Also, the oil pumps induce inherently large drag torque, which affects fuel economy. This research is to overcome these problems of the current system by exploring the utilization of a hybrid type piezo-hydraulic pump device for AT band brake control. This new actuating system integrates a piezo-hydraulic pump to the input of the band brake. Compared with the current systems, this new actuator features much simpler structure, smaller size, and lower weight. This paper describes the development, design and fabrication of the new stand-alone prototype actuator for AT band brake control. An analytical model is developed and validated using experimental data. Performance tests on the hardware and system simulations utilizing the validated model are performed to characterize the new prototype actuator. It is predicted that with increasing of accumulator pressure and driving frequency, the proposed prototype actuating system will satisfy the band brake requirement for AT shift control.

In this paper, a research for the effectiveness enhancement of a Cycloidal Wind Turbine by individual active control of blade motion is described. To improve the performance of the power generation system, which consists of several straight blades rotating about axis in parallel direction, the cycloidal blade system and the individual active blade control method are adopted. It has advantages comparing with horizontal axis wind turbine or conventional vertical axis wind turbine because it maintains optimal blade pitch angles according to wind speed, wind direction and rotor rotating speed to produce high electric power at any conditions. It can do self-starting and shows good efficiency at low wind speed and complex wind condition. Optimal blade pitch angle paths are obtained through CFD analysis according to rotor rotating speed and wind speed. The individual rotor blade control system consists of sensors, actuators and microcontroller. To realize the actuating device, servo motors are installed to each rotor blade. Actuating speed and actuating force are calculated to compare with the capacities of servo motor, and some delays of blade pitch angles are corrected experimentally. Performance experiment is carried out by the wind blowing equipment and Labview system, and the rotor rotates from 50 to 100 rpm according to the electric load. From this research, it is concluded that developing new vertical axis wind turbine, Cycloidal Wind Turbine which is adopting individual active blade pitch control method can be a good model for small wind turbine in urban environment.

Rotationally periodic structures, like turbine, bladed disks, stators and rotors of electric machinery or satellite antennae, play a very important role in many fields of the technology. It is well known that when even small structural imperfections are present, destroying the perfect periodicity of the structure, each couple of degenerate modal frequencies splits into two different values (mistuning) and the corresponding modal shapes exhibit peaks of vibration amplitude (localization phenomenon). In this paper, a continuous model describing the in-plane vibrations of an imperfect bladed rotor is derived via the homogenization theory and is applied to the analysis of the localization phenomenon. Imperfections are modeled as perturbations of the geometrical dimensions and material characteristics of some blades, and a perturbation approach is adopted in order to find out the split eigenfrequencies and eigenmodes of the imperfect structure. Numerical simulations show that the proposed model is suitable and effective for the identification and analysis of the localization phenomenon, requiring much lower computational effort than classical finite element models.

We aim to develop the easy-to-use artificial larynx with high tone quality. We focus on using a PZT ceramics sounder as its sound source, because it is small size, low power consumption, and harmless to humans. But conventional PZT ceramics sounder have the problem that it cannot generate an enough sound in the low frequency range, thus they cannot be used for artificial larynx. Then, we aim to develop the PZT ceramics sounder which can generate enough volume in the low frequency range. If we can lower the resonance frequency of the sounder, it can generate low pitch sound easily. Therefore I created the new diaphragm with low resonance frequency. In addition, we could obtain the high amplitude by changing method of driving. This time, we report on the characteristic comparison of this new PZT ceramics sounder and conventional one. Furthermore, for this new one, we analyzed the best alignment of PZT ceramics and the shape of the diaphragm to obtain low resonance frequency and big amplitude. In fact we analyzed the optimization of the structure. The analysis is done by computer simulation of ANSYS and Laser Doppler Vibrometer. In the future, we will add intonation to the generated sound by input wave form which is developed concurrently, and implant the sounder inside of the body by the method of fixing metal to biomolecule which is done too. And so high tone quality and convenient artificial larynx will be completed.

This paper describes a method to vary the flexural bending stiffness of a multi-layered beam. The multi-layered beam comprises of a base layer with polymer layers on the upper and lower surfaces, and stiff cover layers. Flexural stiffness variation is based on the concept that when the polymer layer is stiff, the cover layers are strongly coupled to the base beam and the entire multi-layered beam bends as an integral unit. In effect, we have a "thick" beam with contributions from all layers to the flexural bending stiffness. On the other hand, if the shear modulus of the polymer layers is reduced, the polymer layers shear as the base beam undergoes flexural bending, the cover layers are largely decoupled from the base, and the overall flexural bending stiffness correspondingly reduces. The shear modulus of the polymer layer is reduced by increasing its temperature through glass transition. This is accomplished by using embedded ultrathin electric heating blankets. From experiments conducted using two different polymer materials, polymer layer thicknesses and beam lengths the flexural stiffness of the multi-layered beam at low temperature was observed to be between 2-4 times greater than that at high temperature.

In this paper, we examine and compare four different techniques for modal analysis of stepped piezoelectric beams. The first technique is based on the solution of the exact transcendental eigenvalue problem, formulated in terms of the dynamic stiffness matrix. The other three techniques are based on the Galerkin method for obtaining a finite-dimensional version of the system. Besides the classical assumed modes method and finite-element method, we propose a novel enhanced version of the assumed modes method, which introduces special jump functions to enrich the standard basis functions.

The advent of micro and nanotechnologies along with integrated circuit technologies has led to many exciting solutions in medical field. One of the major applications of microsystems is microelectrodes interfacing neurons for large scale in vivo sensing, deep brain stimulation and recording. For biomedical microsystems, material selection is a challenge because biocompatibility has to be considered for implantable electronic devices. We are using flip chip bonding to integrate a signal processing IC to the Utah electrode array (UEA). Conventionally the flip chip process is used to bond a die to a substrate or interposer. In this work the electrical interconnects are made from the under bump metallization (UBM) on the UEA to the solder bumps on the IC. The UBM selection and reliability is one of the critical issues in the total reliability of a flip chip bumping and interconnection technology. The UBM was optimized to achieve improved interconnect strength, and its reliability was evaluated by conducting solder ball shear strength testing. The UBM reliability was tested with two solder metallurgies including AuSn and SnCu0.7. These solders are needed to allow two reflow processes to be used, an initial higher temperature (350 °C) and a second lower temperature process (250 °C).

A Smart Vortex Generator (SVG) concept has been proposed, where the SVG is autonomously transformed between an upright vortex-generating position in take-off and landing and a flat drag-reducing position in a cruise. This SVG is made of a Shape Memory Alloy (SMA), which is in the austenite phase and memorizes the upright position at high temperatures of the take-off and landing. At low temperatures during ascent the SVG is transformed into a martensite phase, and it lies flat against a base structure due to external or/and internal forces. In this paper, we examine whether the SVG can be transformed into the drag-reducing position by an aerodynamic force. To this end, numerical simulations are carried out with a simple line element model. The aerodynamic force applied on the SVG is calculated by a commercial CFD program. Result reveals that this SVG can be transformed from the upright vortex-generating position into the drag-reducing position by just an airplane climbing, and vice versa, if the SMA applied to the SVG has the two-way shape memory effect. If the SMA has the one-way shape memory effect, it is necessary to reduce the stiffness of the SVG or/and use a counter spring.

Superelastic shape memory alloy (SMA) is a potential candidate for use in structure damping devices due to its unique mechanical properties. In order to mitigate the vibration of a structure subjected to earthquake tremors from different directions, an innovative, multi-directional SMA-based damper is advanced. The damper, with two movable cylinders attached to four groups of SMA strands arranged in a radial symmetry, can not only function in a plane, but also can work vertically and rotationally. Based on experimentation, the Graesser model of superelastic SMA is determined. By analyzing the damper's mechanism working in different directions, the corresponding theoretical models are developed. Numerical simulations are conducted to attain the damper's hysteresis. Working in a plane, the damper, with a 3% initial strain, provides a rectangular hysteresis with the maximum amount of damping. A rectangular flag hysteresis can be supplied in the absence of a pre-stress in the wires, going through the origin with a moderate amount of energy dissipation and higher force capacity. Moreover, the damper has better working capacities (i.e. force, stroke and energy dissipation) if the deflection is parallel to the internal bisectors of the tension axes. Working vertically or rotationally, similar triangular flag hysteresis is generated with small energy dissipation and a self-centering capacity. For a given deflection, the initial strain (3%) increases the force of the damper, but decreases its stroke.

In this paper, a simply supported thin cylindrical shell segment excited by a pair of collocated PZT actuators is studied. A closed-form solution has been obtained to describe the radial vibration of the shell. Based on this solution, optimal placement of the pair of PZT actuators in terms of maximizing the vibration of shell is discussed and numerically verified. It is found that the pattern of the optimal locations of the PZT actuators can be represented by a simple function, namely, the position mode function (PMF) or their combinations.

We present a framework for the design of a compliant system; i.e. the concurrent design of a compliant mechanism with embedded actuators and embedded sensors. Our methods simultaneously synthesize optimal structural topology and placement of actuators and sensors for maximum energy efficiency and adaptive performance, while satisfying various weight and performance constraints. The goal of this research is to lay an algorithmic framework for distributed actuation and sensing within a compliant active structure. Key features of the methodology include (1) the simultaneous optimization of the location, orientation, and size of actuators concurrent with the compliant transmission topology and (2) the concepts of controllability and observability that arise from the consideration of control, and their implementation in compliant systems design. The methods used include genetic algorithms, graph searches for connectivity, and multiple load cases implemented with linear finite element analysis. Actuators, modeled as both force generators and structural compliant elements, are included as topology variables in the optimization. Results are provided for several studies, including: (1) concurrent actuator placement and topology design for a compliant amplifier and (2) a shape-morphing aircraft wing demonstration with three controlled output nodes. Central to this method is the concept of structural orthogonality, which refers to the unique system response for each actuator it contains. Finally, the results from the controllability problem are used to motivate and describe the analogous extension to observability for sensing.

We report recent progress in the development of low modulus, highly electrically conducting thin film sheet and fabric materials and devices formed by molecular-level self-assembly processing methods.

To predict the effect of active control on aircraft or helicopter trim panels, made with honeycomb sandwich composite, one approach consists in modeling the panel by Finite Element Method. FEM with shell elements for the laminate and volume elements for the core is classically used in industry; in a previous study the homogenized modeling approach has been validated. The aim of the present paper is to make a test/analysis comparison of the dynamic behavior of a honeycomb core sandwich beam actuated by a piezoelectric patch. More precisely, the behavior in the vicinity of the piezoelectric actuator is characterized, in order to validate the modeling approach of honeycomb sandwich composite equipped with piezoelectric patches.

A new designing concept to realize multifunctional structural material systems without using sophisticated functional materials was proposed and demonstrated in this paper. The concept can be explained as follow: There exist a couple of competitive structural materials which normally compete with each other because of their similar and high mechanical properties, and they tend to have another property which is different from each other or opposite among them. So if they are combined together to make a composite, the similar property, normally high mechanical property, can be maintained, and the other dissimilar property conflicts with each other, which will successfully generate a functional property without using any sophisticated functional materials. According to this concept, two examples, that is, a CFRP/Al active laminate and a Ti fiber/Al multifunctional composite were made and it was successfully demonstrated.

This paper demonstrates the design, fabrication, and analysis of a small plastic latching accelerometer, or shock sensor, that is bi-stable and functions without the use of electricity. The sensor has two stable mechanical states. When force above a certain threshold limit is applied, the sensor changes states and remains in the changed state indicating the amount of force that has been applied to the sensor. The devices were laser-cut from ABS and Delrin plastics, and the surface area of the free-moving section was varied to produce sensors with a range of force sensitivities. The switching action of the devices was analyzed with the use of a centrifuge, which supplied the necessary force to switch the accelerometers from one mechanical state to another. The surface area of the sensors varied from 100 mm² to 500 mm² and the G-force sensitivity range varied between 10 and 800 g.

This paper presents a means for creating optical fiber sensors that are capable of detecting electric fields. This novel E-field sensor is formed as part of a contiguous fiber resulting in a flexible and small cross-section device that could be embedded into electronic circuitry. The sensor is formed by partially etching out the core of a D-shaped optical fiber and depositing an electro-optic polymer. Using PMMA and DR1 for proof of concept, we demonstrate the operation of the first in-fiber hybrid waveguide electric field sensor with a sensitivity of less than 100 V/m at a frequency of 2.9 GHz. Sensors optimized for low loss (~1dB) have an estimated E&pgr; of 222 MV/m. A sensor with an E&pgr; of 60 MV/m is also demonstrated with an insertion loss of 14.4 dB.

Piezoelectric structures are used in a variety of applications where instant response, high energy conversion efficiency and accurate control are required. However, in the actuation domain they present an important drawback, which is the small displacement capacity. In the present work non-linear mechanics and more specifically snap-through buckling are used to transform a traditional bimorph structure with two piezoelectric layers and an aluminum substrate into a non-linear high displacement actuator with increased combination of force/displacement output. Large displacements are attained with the transition of the structure from one equilibrium position to another. A closed form analytical solution for the snap-through behavior of piezoelectric/composite beams is presented. The effect of piezoelectric actuation is introduced in this model through equivalent bending moments produced through the bimorph setting of the piezoelectric actuator. Classical Laminated Plate Theory (CLPT) is used for the elaboration of an equivalent single layer structure that takes into account the influence on the stiffness of the structure due to the piezoelectric layers. During the development the importance of boundary conditions has been revealed and thus it has been modeled too. Results from finite element analysis as well as the actuators' construction and the experimental setup and subsequent results are presented.

The goal of the project is to develop active mounts that isolate the main power engine using piezoceramic actuators operating in the load transmission of the common engine mounts. These mounts are to use high-frequency conducted adaptive countermeasures to reduce the unwanted vibrations caused by the motor. Integrating the active piezoceramic based Interfaces directly in the load transmission of the mount, which is a safety critical component, the system reliability of these mounts will face special challenges. Designing these active mounts several measures on the target ship have been done. Based on these measurements simulations of the dynamic behavior of the ship, the passive mounts and the aggregate have been done to design the active mounts and to simulate its properties to optimise and to design e.g., the adaptive control in a early state of the project. For the experimental research a test rig with a reduced ship structure and the main engine was build up at the LBF to investigate the performance and the system reliability of the active mounts. The project started in 2004, has an intended duration of three years and will end with the presentation of a ship with the abovementioned active mount.

This paper discusses small deformable mirrors based on thin metallized membranes and designed for steering and focusing of beams as well as providing correction for a small number of optical aberration modes. We consider circular membranes driven electrostatically by four electrodes deposited on or milled into a light weight substrate. The metallized surface on the membrane, while acting as a mirror also provides the ground electrode to enable actuation. Here we discuss prototype testing of the mirrors based on different production techniques, and report on closed loop control studies using two formulations: (1) an approximate lumped-parameter model based on a single-input-single-output linearized treatment, and (2) a linearized, continuous parameter model leading to a multiple-input-multiple-output state space system via modal expansion. A quadrant photo-detector ("quad cell") is used as an output sensor.

This paper introduces a simple and robust technique for vibration control in smart structures with collocated sensors and actuators. The technique is called Integral Resonant Control (IRC). We show that by adding a direct feed-through to a collocated system, the transfer function can be modified from containing resonant poles followed by interlaced zeros, to zeros followed by interlaced poles. This structure permits the direct application of integral feedback and results in good stability and damping performance. To alleviate the problems due to unnecessarily high controller gain below the first mode, a slightly complicated second-order controller is also discussed. A piezoelectric laminate cantilever beam used to test the proposed control scheme exhibits up to 24 dB modal damping over the first eight modes.

This paper presents a new type of jetting dispenser featuring piezoelectric actuator in order to achieve high flow rate and small dot sizes in semiconductor packaging processes. After describing structural components of the dispensing mechanism and the operating principle, a dynamic modeling is undertaken by considering the behavior of the piezostack, hydraulic magnification, dispensing needle and adhesive fluid. In the modeling, fluid models for adhesive fluid and hydraulic magnification are derived with a dumped parameter method. The governing equation of motion is then derived by integrating the fluid models with structural model. Subsequently, the dynamic behavior of the dispenser and its dispensing amount are investigated by applying several types of square wave driving voltage input and design parameter values are determined.

This paper discusses microprocessor based variable slip-force level damper system providing one of the autonomous-decentralized structural control schemes. This damper system consists of several dampers distributed to several floors in a building. Either each damper or each group of dampers is autonomously controlled by its decentralized controller, then providing an autonomous-decentralized control system. Autonomous-decentralized control seems very appropriate for a huge building. In this paper, as a decentralized controller, a microprocessor is utilized with very simple control algorithm integrated. The validity of the proposed control system is demonstrated by conducting experiments along with computer simulation incorporated.

A method for adaptive energy absorption in the low frequency region of acoustic cavities is presented. The method is based on an adaptive scheme consisting of a self-tuning regulator (STR) that has the ability to target multiple modes with a single actuator. The inner control loop of the STR uses positive position feedback (PPF) in series with a high- and low-pass Butterworth filters for each controlled mode. The outer loop consists of an algorithm that locates the zero frequencies of the collocated signal and uses these values to update the resonance frequency of the PPF filter and the cut-off and cut-on frequencies of the Butterworth filters. Experimental results of a duct are provided that show how less than a 10 percent change in the frequencies of the acoustic modes of the duct will cause a non-adaptive controller to go unstable, but the STR will maintain stability and continue absorbing energy through a 20 percent change in the frequencies of the acoustic modes of the duct. Additional experimental results of a fairing replica are provided that show internal temperature variations can change the frequencies of the acoustic modes of this larger cavity and that the STR can adapt to these changes and absorb acoustic energy.

Lightweight design is gaining more and more importance in the automotive industry. Engineers are trying hard to reduce the increased weight of chassis due to safety and comfort issues. This paper presents new achievements in the field of control design for smart structures, targeting at innovative lightweight, high-performance and low-noise engineering constructions with integrated embedded systems technology: The first part of the paper focuses on new developments in the field of low-cost, highly efficient smart structure power electronics for piezoelectric elements. These elements will be integrated into automotive chassis, which are able to measure any structure-borne disturbance such as vibrations. The second part of the paper presents frontier research in the design of a high-performance control concept for smart structure applications. This innovative control concept based on a nonlinear state observer design, targets at highly robust and broadband suppression of structure-borne noise in terms of fast changing frequencies. The controller performance is not only assessed with respect to stability and disturbance rejection but also with respect to technical feasibility and implementation issues (required sample rate, rounding errors due to inappropriate data formats, latency, etc.).

Dynamic modeling of smart hull structure with advanced piezoelectric actuator; macro-fiber composite (MFC) actuator, is developed and control performance to suppress structural vibration of the system is studied. Finite element technique is used to ensure application to practical geometry and boundary conditions of smart hull structure. Modal analysis is conducted to investigate the dynamic characteristics of smart hull structure. For the verification of the proposed finite element model, numerical results of modal analysis are compared with those of experimental modal test results. Modal mass and stiffness matrix of smart hull structure are extracted for the controller design. Active controller is designed to suppress structural vibration of smart hull structure and control performance is evaluated in the resonance and non-resonance regions.

The dynamic equations of piezoelectric benders are studied in this paper, considering nonlinear behavior of piezoceramics. A second order approximation of constitutive equations of piezoceramics is used to account for reversible nonlinearities. Transversal and longitudinal deflections at the tip of the beam and the blocking force as well as sensor equations (output charge as a function of external loads) are obtained under static conditions. The static equations are then used to construct a linear dynamic model for actuation. A Bouc-Wen type hysteresis model is employed in order to account for the irreversible nonlinearities. The final equation of motion is in the form of well-known Hill's equation.

A general modeling scheme is proposed for precision positioning of piezoelectrically-driven flexural systems. To describe the nonlinear behavior of the structure while also considering the system dynamics, a second order linear dynamic model subjected to nonlinear hysteretic input is first adopted. Using the memory-dependent properties of hysteresis nonlinearity, a new mathematical framework is then proposed for describing this phenomenon. More specifically, a nonlinear mapping strategy is proposed for the approximation of each of the ascending and descending multiple-loop hysteresis curves based on the shape of hysteresis reference curves. The trace of internal hysteresis trajectory is, however, obtained based on the locations of the past turning points, corresponding to the input extrema. Experimental tests are carried out on a dual-axis piezoelectrically-driven flexural stage to demonstrate the contribution of dynamic and hysteresis models, individually and combined together, on the improvement of the model response. Results indicate that the proposed hysteresis model can effectively predict the nonlinear response of the system, while the influence of dynamic model is more apparent for high rate inputs.

Piezoelectric patches shunted with a negative capacitance circuit represent an effective broadband active control methodology. Recent developments have shown that a wave-based tuning of such shunts applied to beams yields varying levels of control depending upon the configuration, with the most effective configuration being that of a shunt at the root of the beam. That configuration yielded effectively an anechoic termination. The effectiveness of the different configurations may be interpreted through their ability to couple to and suppress the reactive input power delivered by a point excitation, as is demonstrated in this paper. The reactive input power suppression concept is extended to the case of vibration suppression on a rectangular panel, and is shown to predict significant vibration suppression capability.

The implementation of semi-active friction damper for vibration mitigation of seismic structure generally requires an efficient control strategy. In this paper, the fuzzy logic based on Takagi-Sugeno model is proposed for controlling a semi-active friction damper that is installed on a nonlinear building subjected to strong earthquakes. The continuous Bouc-Wen hysteretic model for the stiffness is used to describe nonlinear characteristic of the building. The optimal sliding force with friction damper is determined by nonlinear time history analysis under normal earthquakes. The Takagi-Sugeno fuzzy logic model is employed to adjust the clamping force acted on the friction damper according to the semi-active control strategy. Numerical simulation results demonstrate that the proposed method is very efficient in reducing the peak inter-story drift and acceleration of the nonlinear building structure under earthquake excitations.

The studies reported on in this paper are of relevance to automated diagnosis of light weight space structures based on membranes. We investigate in-plane vibration response of membranes to in-plane actuation. Identically shaped piezoelectric polymer strips are used both for actuation and sensing. For membrane strips, the frequency response function is obtained using an in-plane vibration model. The model for the intact membrane is then modified to analyze the effect of a transverse crack at mid-span. The theoretical results are compared with experimental measurements. Experiments on a cracked strip show small differences in the frequency response function, which are qualitatively borne out by the theoretical calculations. Some experimental results on membrane sheets are also presented.