I would like to share with you my experience of developing shearography and transferring the technology to industry. Shearography has already received wide industrial acceptance for nondestructive testing. Currently the rubber industry is routinely using shearography for evaluating tires and the aerospace industry has adopted the technique for nondestructive testing of composite structures. Many other industrial applications of shearography are presently underway. These include material evaluation, measurement of strains, residual stresses, 3-D shapes, fluid temperature, as well as vibration studies. There are three versions of shearography employing different recording media: photographic emulsion, thermoplastic and digital. Digital shearography employs a computerized process which is much more superior to the former versions. It uses video sensors (such as CCD) as recording medium and digital image processing technology to acquire the results thus eliminating the consumable materials used by the photographic and thermoplastic versions. Furthermore, the computerization of shearography has led to the automation of data deduction. This talk reviews computerized shearography and its applications.

The industrial requirement for higher efficiency, lean performance, airframe structures to form the basis of more cost effective Commercial Aircraft has encouraged developments in all aspects of aeronautical design and manufacture. Until recently the main emphasis has been in the area of computer and numerical analysis, however new developments in experimental mechanics are emerging as very powerful tools for use in the validation of numerical analyses and for primary stress analysis data. The developments described have been forced by economic drivers that address more efficient analysis techniques with respect to cost, specific weight and expended time for analysis.

The main objective of this work is to provide detailed measurement of the full 3-dimensional weld pool shape for the Gas Metal Arc Welding (GMAW) process. Relationships between the welding process variables and important pool shape parameters have been established, and the measured profile is in an appropriate form for use in numerical models of the GMA welding process. A mechanical ejection device instantaneously emptied the molten metal from weld pool by rapidly accelerating and decelerating the test plate being welded. A non-contact laser profiling system is used for accurate measurement of the exposed weld pools. Welding speed and welding current are found to have the greatest influence on the length of a weld pool, and increasing heat input level yields higher values for all critical weld pool dimensions.

Stereoscopic image processing technique was used to detect the surface waves in an experimental water tank. The amplitude and the frequency of these waves were measured and they were compared with a well known technique.

Repeated rain drop impact plausibly brings about a definite damage in airplane surface materials while the airplane flies in rain fall. When the materials are fiber reinforced plastics (FRP), the damage is more serious. However, FRP is a very attractive material to the aircraft, because its specific strength, that is the strength per unit density, is very high as compared with the other materials such as aluminum alloys. This paper investigates the damage mechanism of the glass fiber reinforced plastics subject to repeated rain drop impact and the residual strength after the certain number of the impacts. This experimental result shows that the residual strength decreases significantly after delamination takes place in the FRP.

The sensitivity, flexibility, compactness and lightness of an optical fiber are utilized to monitor the acoustic waves propagating in a film. In this work, the wave is initiated by the irradiation of a pulsed Nd^--YAG laser line focused onto the film surface through a cylindrical lens. The sensing arm of a Mach-Zehnder fiber optic interferometer sensor is attached to the film at a known distance from the focus to pick up the acoustic signal. The laser pulse also provides the essential synchronizing trigger to measure the arrival time of the acoustic wave. The speed of the wave through the film can be evaluated from the wave propagation time and the position of attachment of the sensing fiber. The modulus of the film can then be deduced from the speed of the wave. The sensor is stabilized against thermo-drift with a thermal feed back circuit and enhanced in visibility with a polarization controller. The moduli of several metal, polymer and diamond- like carbon films have been obtained by this method.

The fundamental principles of infrared stress pattern analysis are briefly described and its quantitative analysis method and some application examples are given in this paper.

A new electronic shearing speckle pattern interferometry using a special Ronchi grating as the shearing element has been developed and applied to deformation measurement and non destructive testing (NDT) in the practical environment. This special designed Ronchi grating is a kind of phase grating. It can make zero order and all even order beams disappear and among all odd order beams the +/- 1 order beams are much stronger than others. This new shearing element has many advantages, such as small volume, light weight, lower price, lower energy lost and good quality of shearing image. The experimental results show that it is good at electronic shearography.

A new system for deformation visualization has been developed, being a real time phase stepped shearing speckle interferometer. This system provides the possibility to measure quantitatively deformations of diffusely reflecting objects in an industrial environment. The main characteristics of this interferometer are its speed of operation and its reduced sensitivity to external disturbances. Apart from its semiconductor laser source, this system has a shoe-box size and is mounted on a tripod for easy handling during inspection. This paper describes the shearing speckle interferometry set-up, as it is developed at our laboratory and its potential for detecting defects.

This paper presents a novel method for measuring whole field in-plane displacement by using optical fiber phase-shifting ESPI. A 1 X 4 single mode optical fiber beamsplitter is employed to split the laser beam into four beams of equal intensity. We use one pair of fibers to illuminate the diffuse target at equal angles in the horizontal plane so it is sensitive only to horizontal in-plan displacement. Another pair of optical fibers is set to be sensitive only to vertical in-plane displacement. The polarization directions of light emitted by fibers are same for each pair but are at right angle between pairs. The optical fibers are equal in length for each pair but are not equal between two pairs. In this case the speckles are interference itself for each pair fibers, respectively, so we can get the horizontal and vertical displacement components simultaneously. By means of fiber phase shift technique we can obtain the quantitative data of whole field. This method has enabled to study the in- plane displacement of a thin metal plate, and the examples of the results obtained are shown to demonstrate the novel method.

New methods of deformation analysis using electronic speckle pattern interferometry is proposed. The advantages of the measurement system are its capability to evaluate the phase data embedded in fringe pattern continuously, by simply taking speckle images and doing simple arithmetic operation on data processing stage. The methods can be applied for deformation analysis and fracture prediction technique on a loaded material. Analysis of fracture was done based on mesomechanics theory proposed by V. E. Panin. The important strength of this system is the ability of predicting a future crack on a loaded material by performing non contact and non destructive measurement system.

Success of dental restorations is dependent on the integrity of the tooth/restoration interface. Distortion of teeth due to operative procedures has previously been measured using LVDT's and strain-gauges and has provided useful but limited information. This paper reports on the verification of a system for laser speckle photography and its use to quantitative distortions in teeth from matrix band application and the use of bonded composite resin restorations. Tightening of matrix bands around teeth results in an inward deformation of the cusps, increasing incrementally as the band is tightened. Deflections of 50 micrometer/cusp were recorded. A delayed recovery was noted consistent with the viscoelastic behavior of dentine. For bonded restorations recovery will place the adhesion interface in a state of tension when the band is released and may cause premature failure. Premolar teeth restored with bonded resin restorations exhibited inward displacement of cusps of 12 - 15 micrometer. Deformation was not within the buccal-lingual axis as suggested by prior studies. Molar teeth bonded with composite resin restoration exhibit complex and variable cusp displacement in both magnitude (0 - 30 micrometer) and direction. Complete and partial debonding could be detected. Interproximal cusp bending could be quantitated and lifting of the restoration from the cavity floor was detectable. Deformations evidenced indicate the tooth/restoration interface is in a stressed state and this may subsequently lead to failure. The technique has the potential to aid in development of restoration techniques that minimize residual stress.

In this paper, we present the developmental details of an all fiber optic phase shifting Electronic Speckle Pattern Interferometer (ESPI) and its applications in Non-Destructive Evaluation (NDE) of Glass Fiber Reinforced Plastics (GFRP). Laminates made of GFRP are studied using the developed ESPI system in its shear configuration. This provides a full-field, non-contact method for NDE, and also observation of surface strains which are proportional to displacement derivatives. Since defects in objects usually induce strain concentrations, shear ESPI reveals defects by identifying anomalies in strain concentration. Experiments have been carried out for NDE of unidirectional GFRP specimens at different fiber orientations and having programmed defects. The experimental results are compared with the theoretical predictions.

The extra-low temperature has great influence on the mechanical properties of the material which is used widely in aerospace science and others. In our experiment of stretching the Extra-Low-Interstitial (ELI) Ti-5-Al-2.5Sn specimen, we found a new phenomenon of metal mechanics -- multi-necking. The contour of the specimen was also measured. We presented an experimental scheme of digital speckle pattern interferometry in room temperature to observe the in-plate deformation field of the whole process from the beginning of elastic deformation to the end of plastic deformation until fracture. Experimental results of the low temperature and normal temperature are much alike, expect for the difference of the multi-necking quantity. Based on the experiment results, a rough explanation was presented.

In this paper, efforts on the measurements of material properties of multi-layered fiber reinforced composites such as graphite epoxy employing an inverse method based on Genetic Algorithms (GAs) using oblique incidence ultrasonic velocity data will be discussed. Both, direct as well as inverse genetic methods were used in this effort. The phase velocity data as a function of the angle of incidence as well as the azimuthal angles for orthotropic uni-directional composite laminates were used as the input to the Genetic Algorithm. Optimal parameters were chosen from the sensitivity analysis using a direct approach. Then, inversion algorithms was introduced to compute the material properties from the ultrasonic phase velocity data. Sensitivity as well as accuracy of the techniques are also discussed for both noise- free and noisy simulated data sets.

Knowledge of the thermal conductivity and the thermal diffusivity are the two most important properties for thermal management in microelectronics design. However, it is difficult to measure the thermal conductivity of ordinary bulk materials accurately, especially of materials that have extremely high values such as copper (4 W/cm.K) and diamond (10 to 25 W/cm.K). In this paper, we proposed and demonstrated three methods for measuring the thermal conductivity of bulk materials based on the nondestructive testing technique in holographic interferometry. Their efficacy for measuring high thermal conductivity values of diamond materials is analyzed. We have obtained values of thermal conductivity for aluminum alloy, copper alloy and pure copper, and molybdenum using these methods. The result from one of these methods shows that it is feasible to achieve such measurements for diamond and diamond-like materials. However, to determine the thermal conductivity of diamond materials the method requires that the thermal diffusivity of the sample must be first measured under high thermal excitation. It is also necessary to capture the dynamic thermal process within a fraction of a second.

Reactor pressure vessels under some special regime (e.g. pressurized thermal shock) are loaded by a strongly biaxial tensile stresses that ratio can reach even an opposite value in comparison with normal operating conditions. Pressure vessel integrity as well as its life assessment is performed on the basis of fracture mechanics where normally only uniaxial fracture toughness of materials are used as material input data. Special biaxial tests on cruciform type specimens with thickness up to 90 mm are tested in our Institute -- special testing equipment and testing methods including measurements have been developed and realized. Testing equipment with maximum loading capacity up to 1.5 MN allows to reach different biaxial loading ratios between 0 and 2. During tests, carried out mostly at low temperatures, specimens deflections, strains, load and crack opening displacement are measured and then evaluated. Biaxial loading results in some decrease in fracture toughness compared with uniaxial test results.

TiAl intermetallic compound with composition of Ti-58at.%Al was synthesized from elemental Ti and Al powder mixture. X-ray measurement showed the presence of both face-centered- tetragonal TiAl phase and face-centered-cubic TiN phase. The formation of TiAl can be divided into three stages: (1) solid solution, (2) partial amorphization, and (3) formation of TiAl phase. The process of formation of TiAl phase via mechanical alloying took about 40 to approximately 50 hours.

In a previous study, an optical corrosion-meter was built based on a mathematical model relating surface and bulk behaviors of metals in aqueous solution. The optical corrosion-meter was established based on principles of holographic interferometry for measuring microsurface dissolution, i.e. mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e. corrosion current. The corrosion-meter consists of an electrochemical cell in which the sample is immersed in aqueous solution. Furthermore, the corrosion-meter has a holographic camera with a thermoplastic film for in situ processing holograms in order to obtain real time-holographic interferoms of the sample in the electrochemical cell. Results of the present work indicate that optical holography is very useful technique for measuring the corrosion current density underneath coatings of different alloys in aqueous solutions. As a result, the corrosion current density of coated aluminum, low carbon steel, copper, and brass in 1 M KCl, 1M NaOH, seawater and seawater solutions, respectively, were obtained. The obtained corrosion data from the optical corrosion-meter (interferometric technique) were compared with corrosion data obtained on the same alloys in the specified solutions from the alternating current (AC) impedance spectroscopy with linear polarization, electrochemical techniques. The comparison among the two techniques indicates that there is contrast in the results among the investigated alloys. In general, the new method of optical interferometry can be considered more conservative method of corrosion measurement with respect to the alternating current (AC) impedance spectroscopy.

Holographic interferometry of phase objects as well as diffusely scattering opaque specimens is achieved in quasi real-time using two-wave mixing in photorefractive Bi₁₂SiO₂₀ (BSO) crystals. In the case of diffusely scattering specimens, phase shifting holographic interferometry of a vibrating plate specimen is done by recording at least 3 double pulse holograms with different phase shifts of the reference beam. The good signal-to-noise ratio and resolution of the resulting holographic interferograms enable phase measurement of complex vibration modes. Quasi-heterodyne interferometry is also demonstrated for phase objects under non-recurring loading. A double exposure hologram with two separate reference beams at different incident angles for the two exposures is recorded in a BSO crystal. The two recorded object states are subsequently reconstructed by the reference beams at any desired phase by simply introducing a relative phase shift between the two readout reference beams. Because of the speed of the photorefractive effect and the lack of need for post processing, such a recording material allows image acquisition comparable in temporal resolution to electronic speckle techniques with the image quality of classical holography.

In mechanically fastened single lap joints, such as those employed on aircraft fuselage skin splices, there are two distinct mechanisms of load transfer. At low values of load the transfer occurs primarily through friction between the component sheets while at higher loads the load is transferred by friction as well as through bearing at the fasteners. The load level at which the bearing mode of load transfer comes into action significantly affects the fatigue life of the joint, since the fasteners are stressed only at loads above this threshold load value. The portable holographic interferometry testing system (PHITS) is a robust, portable and sensitive non-destructive inspection system which produces contours of relative out of plane displacement by the method of superposition. PHITS is applied here to monitor the load transfer mechanism and identify the threshold at which the bearing mode comes into effect. In the friction mode there is no relative displacement between the fasteners and the skin panels. In the bearing mode the fasteners are loaded, causing a distinct tipping of the rivets, which is readily observable in the fringe pattern of deflection contours recorded by the holographic system.

Surface and plate acoustic waves are commonly used to nondestructively investigate the near-surface region of a solid component for cracks and other defects. An attractive method of generation and detection of ultrasonic signals is laser based ultrasonics (LBU). Because it is non-contact, LBU can be implemented for inspection of limited access components using optical fibers, requiring only a small cross-sectional area for access. The work presented here employs optical fibers to remotely generate and detect ultrasound with energy focused into a selected narrow frequency band. The generation system uses a binary diffraction grating to separate the single laser beam into 10 equal but spatially separated laser beams which are focused into 10 individual fibers, thereby maximizing optical throughput to the component surface. In addition, a low noise fiberized Sagnac interferometer for ultrasonic signal measurement is discussed. The main advantage of this interferometer is improved signal-to-noise ratio, which has been achieved using an optical frequency shifting technique for biasing to quadrature and for elimination of parasitic interference between sampling beams and other unwanted beams in the interferometer. The Sagnac interferometer is truly path-matched, and as such is insensitive to low frequency thermal fluctuations and vibration noise. An acousto-optic modulator is included in the Sagnac loop, and serves a two-fold purpose: frequency shifting and quadrature biasing. Experimental results are presented for both the fiber-optic ultrasound generating array and the Sagnac interferometer.

Two methods -- the empirical constants and decibel drop -- for sizing defects, which are very close to the probe, in fiber reinforced composites using the pulse echo ultrasonic inspection method were developed and experimental data obtained. The methods relate the reduction in signal amplitude from a defect which is smaller than the probe diameter to the signal from a defect which is equal to or larger than the probe diameter. The empirical constants method was confirmed to produce a higher accuracy than the decibel drop method.

A laser ultrasonic generation and non-contact detection system has been developed. The weak generated ultrasonic signal of nanosecond duration and nanometer amplitude can be detected with a confocal Fabry-Perot interferometer (CFPI). It can be applied to determination of elastic constants of material and flaw detection. The experimental results show that laser ultrasonic technique is practical and effective.

Catastrophic failures of major engineering systems such as the space shuttle or nuclear reactor demands more reliable nondestructive evaluation (NDE) technology to maintain a high level of safety. Reliable defect characterization by NDE depends on its efficiency that eliminates the false confidence level in system performance. Also, the modern damage tolerant design based on fracture mechanics requires the reliability and accuracy of the NDE techniques used to detect and characterize flaws. Inspection codes for industrial components specify the sensitivity levels of an inspection method as well as the rejectable flaw size. For complete defect characterization the electronic imaging technique is widely used. In this work, imaging of defects was carried out on thick weldments of SA - 229 pressure vessel steel. Generation of natural defects like cracks were realized by an innovative and reliable welding technique, and NDE techniques, conventional and advanced ones including acoustic holography were used for the crack characterization. Specimens after the test were machined to reveal the cracks and the actual crack morphology was measured and recorded. Through a computer model, the defect image was reconstructed and visualized at different sections. A comparative analysis on the reconstructed image in a computer, the actual one and the NDE result was carried out.

In this contribution, it is shown that the drawbacks of the frequency-domain automatic focusing technique (FD-AFT) have been eased considerably when the scanned-frequencies are transmitted in a broad band pulse. While the focusing capabilities of the AFT are maintained, substantial reduction in data processing is obtained. In addition, it is shown that the nature of the pulse enables it to be tailored to further enhance the image quality. Simulation results are included to demonstrate the focusing capabilities of the procedure for both two and three-dimensional objects.

Shrink fitted joints have been used in mechanical structures. Recently, joints combining shrink fitting with anaerobic adhesives bonded between the shrink fitted surfaces have been appeared in order to increase the joint strength. In this paper, push-off test was carried out on strength of joints combining shrink fitting with bonding by material testing machine. In addition, the push-off strength of shrink fitting joints without an anaerobic adhesive was also measured. In the experiments, the effects of the shrinking allowance and the outer diameter of the rings on the joint strength are examined. The interface stress distribution in bonded shrink fitted joints subjected to a push-off load is analyzed using axisymmetrical theory of elasticity as a four-body contact problem. Using the interface stress distribution, a method for estimating joint strength is proposed. The experimental results are in a fairly good agreement with the numerical results. It is found that the strength of combination joints is greater than that of shrink fitted joints.

Coherent collimated beam of light, reflected by laterally loaded specularly reflecting front surface of a thin plate is diffracted by a single frequency cross grating placed in between a long focal length field lens and the plate. Combinations of different orders, depending on the results sought, are selectively permitted through the Fourier transform plane where, irrespective of the grating position, the diffracted beams come to focus. The interference of these beams at the recording plane causes the formation of moire fringes. Partial curvature and twist contours are obtained from single exposure while partial slope contours require double exposure. This simple, flexible, in-situ filtering technique thus helps in the complete analysis of plates under lateral loading. It also overcomes limitations with earlier techniques that placed the grating at or after the lens plane.

In this paper, we introduce a novel profilometry based on computer aided image process technique which combines single mode optic fiber phase shifting interferometer as the illumination part of the configuration. The design of the optic fiber interferometer has the follow features: easily adjustable fringe space and rotation, automatic phase shifting. Besides these, it has a number of important advantages over the more conventional methods for producing projection fringes, such as extremely small size and weight, high visible fringes with little noise and absolute sinusoidal intensity distribution etc. These are very important and necessary to dual-measurement with different precision (DMDP) method for automatic phase unwrapping. Fringes generated by the interferometer are analyzed, and the relationship between the fringe phase and height distribution of an illuminated diffused surface is derived. The dual-measurement with different precision automatic phase unwrapping method is described. An example of the profilometry in operation is given.

Recently we have developed a new optical interferometric technique capable of visualizing slip band occurring in a deforming solid-state object. In this work we applied this technique to a tensile analysis of laser-welded aluminum plate samples, and successfully revealed stress concentration that shows strong relationships with the tensile strength and the fracture mechanism. We believe that this method is a new, convenient way to analyze the deformation characteristics of welded objects and evaluate the quality of welding. The analysis has been made for several types of aluminum alloys under various welding conditions, and has shown the following general results. When the penetration is deep, a slip band starts appearing at the fusion zone in an early stage of the elastic region of the strain-stress curve and stays there till the sample fractures at that point. When the penetration is shallow, a slip band appears only after the yield point and moves vigorously over the whole surface of the sample till a late stage of plastic deformation when the slip band stays at the fusion zone where the sample eventually fractures. When the penetration depth is medium, some intermediate situation of the above two extreme cases is observed.

An interferometric fiber optic sensor is used to monitor the vibration of a bar under tension. An analytical formula is derived to relate the density. Young modulus and the physical dimensions of the bar to its frequency of vibration, which is measured through FFT of the monitored signal from the fiber optic sensor. Bars made up of homogeneous materials are tested for the validity of the method, which is then applied to composite materials. In the latter application, an optical fiber, which form an integral part of the sensor, can be embedded into the bar during its fabrication process. For materials of stable moduli, the sensor can be used to measure the tension of the bar. For materials with unstable moduli, during its curing process, the aging period or otherwise, the sensor can be used to monitor the change. The method can also be used as an alternative to measure the moduli of materials and is especially suitable for composite materials. Due to the complexity of a composite material, the modulus measured by this method reflects an average effect of the bulk, whereas a conventional tensile test depends more on localized weaknesses of the composite.

Optical fiber is a powerful element in optical communication and other optical techniques. A novel optical metrology based on optical fiber techniques is presented in this paper. The advantages of this technique provide not only the mini-type apparatus but also a simple phase-shifting method to increase the measuring accuracy. A high birefringence fiber with a beat length of 1.2 mm for phase-shifting technique is introduced. The experimental set-up and the technique principle, details will be discussed. Several application examples of optical metrology based on the optical fiber set-up are presented. The application areas include displacement measurement, 3D shape measurement and nondestructive testing. One of the important features of this advanced apparatus is its ability to apply in small object measurements for the electronic industry.

The evaluation of creep displacement and strain at a high temperature cylinder-nozzle welded joint over its design life of 20 - 30 years is an unresolved problem. The numerical solutions such as the finite element methods may not produce sufficiently accurate results for these high temperature welded joints because of uncertainties in the weld material properties, boundary conditions, constitutive equations, etc. While experimental techniques have, to a degree, been successful for ambient temperature applications, their application to the high temperature problems such as a cylinder-nozzle welded joint have been less successful. This paper outlines the current state-of-art of the experimental techniques that may be used for high temperature displacement and strain evaluation on the surface of a cylinder-nozzle welded joint.

Extended life of power plant can only be achieved if it can be shown that the high temperature components have adequate residual creep life. There is often a significant margin between minimum assured creep rupture properties and the actual properties of a component in service. Regular strain monitoring can demonstrate quantitatively that components are fit for extended service and enable utilities to capitalize on this margin. Hitherto, however, widescale application of high temperature strain monitoring has been prohibitively expensive, technically difficult and unreliable in practice. A method of creep life management of high temperature pressure components is described, employing different means of measuring strain which become more focused and refined as creep life exhaustion progresses. Initially, widespread use is made of a direct strain measuring system, employing low cost gauges or'targets' capable of operation at temperatures ranging up to dull red heat -- circa 600 degrees Celsius. The targets are read intermittently at room temperature by a diode array 'camera,' the 'reading' including universal time and date and a target identifier. This information passes directly to a database, maintaining the integrity of the recorded information and minimizing the possibility of errors. As creep strains approach unacceptable levels, the system has identified the most appropriate components and locations for continuous strain measurement, employing capacitance gauges. It has also prioritized components for plant replacement.

The scope of this work is to determine the apparent stain versus temperature curves for two kind of strain gages. Measurement results of these strain gages as well as a comparison of the behavior of both are presented.

Accurate and reliable life predictions of mechanical components subjected to stress at elevated temperature may be difficult since the mechanical properties of the material are expected to change. The constitutive equations describing the creep behavior may also change due to softening or hardening processes caused by the applied loading conditions. In this paper the response of AISI Type 316 stainless steel at 650 degrees Celsius when subjected to a static tensile stress is examined. A testing technique has been applied to the test material to evaluate the effect of short periods of high temperature deformation on its mechanical properties. Round tensile specimens were subjected to constant tensile stress levels under high temperature of 650 degrees Celsius for periods of time varying from 2 to 8 hours. The specimens were then annealed and tested in tension under room temperature. Test results indicate that the AISI Type-316 exhibited hardening due to short period creep. Yield strength and ultimate tensile strength have increased by 58% and 20%, respectively, after 8 hours creep, over that of the virgin material. Creep was also found to cause a reduction in the ductility of the AISI Type-316 over the temperature and stress levels used in this investigation. Moreover, the changes in these properties were found to increase as creep time increased. From the present work, an empirical equation was obtained for predicting the amount of hardening in the material due to creep. Such an equation may be useful in more involved problems of combined creep and fatigue.

The determination of pressures along the surface of a wind tunnel proves difficult with methods that must introduce devices into the flow stream. This paper presents a sensor that is part of the wall. A special interferometric reflection moire technique is developed and used to produce signals that measures pressure both in static and dynamic settings. The sensor developed is an intelligent sensor that combines optics and electronics to analyze the pressure patterns. The sensor provides the input to a control system that is capable of modifying the shape of the wall and preserve the stability of the flow.

Real-time displacement and vibration measurements are presented, Which are based on a spatial phase-shifting with a tilt holographic interferogram. Three intensity data sampled at every one-third of the fringe spacing of the tilt fringes are used to calculate the phase and the modulation term of the fringe which are functions of a displacement and a vibration amplitude, respectively. Three-dimensional look-up tables perform the calculations in a TV repetition rate to give a phase distribution and a new fringe profile which contours the vibration amplitude. Experimental results are given in two cases of a displacement measurement for a cantilever-like object and a vibration measurement at resonant frequencies of a flat speaker.

Different arrangements for digital double-pulsed holographic interferometry for vibration analysis and shape measurement will be described. For vibration measurement using digital double pulse holographic interferometry, two separate holograms of an object under test are recorded within a few microseconds using a CCD-camera and stored in a frame grabber. The phases of the two reconstructed wave fields are calculated from the complex amplitudes which are obtained by digital reconstruction of the wavefront produced by the hologram. The deformation is obtained from the phase difference. In the image plane hologram the phase can be calculated by using the sinusoid-fitting method or the Fourier method. Using three directions of illumination and one direction of observation, all the information necessary for the reconstruction of the three-dimensional deformation vector can be recorded at the same time. Digital holographic interferometry can be used as well to determine the shape of an object.

Fundamental properties of phase modulation ability of a nematic liquid-crystal (NLC) cell is first studied. Based on the phase modulation property of the liquid-crystal (LC) cell, a new type of speckle shearing interferometer is proposed. In the method, a LC cell is employed as a phase shifter to implement the phase shifting method for the conventional speckle shearing interferometer. Next, a phase unwrapping method that particularly has the advantage of unwrapping of phase distribution with severe noise such as those obtained in speckle interferometry is proposed. Computer simulations were carried out to examine the performance of the proposed method. Finally, experiments were made to demonstrate the usefulness of the proposed phase shifting speckle interferometer together with the improved phase unwrapping method.

The amplitude and phase distributions of sinusoidally vibrating object are measured by use of phase modulation and sub-fringe detection. The resulting high sensitivity enables measurements on objects like high frequency transducers, biomedical membranes and cross sections of sound fields in air and water. For the sound recordings, tomographic reconstruction of several cross-sections produces representation of the sound field in any plane desired. The sub-fringe approach also allows analysis of objects vibrating harmonically. In shear interferometry we measure true derivatives as very small shear may be used. Used in Moire systems, large amplitude vibrations can be measured. The integration of the recording media is the main drawback of the video system when used for general vibration analysis.

We describe a compact shearing interferometric system for the measurement of full-field stress distributions of optically isotropic, transparent structures. Design of the system is based on the consideration that the analysis of the experimental data should be automated so as to obtain results with high spatial resolution and high accuracy. To this end, a specially designed Wollaston prism is used to generate a pair of spatially displaced beams when the prism is illuminated by a collimated laser beam. The two sheared and orthogonally polarized versions of the laser beam interfere with each other by the use of an analyzer. In addition, the special prism can also generate a set of parallel and equally spaced carrier fringes in the interference pattern of the shearing interferometer. The presence of the carriers greatly facilitates the analysis of the fringe patterns obtained in the interferometer when a Fourier transform phase measurement technique is applied. Experiments performed include several specimens with different configurations and materials, namely: (1) a homogeneous PMMA specimen with a crack; (2) a PMMA/aluminum bi-material specimen with an interfacial crack and (3) a PMMA/aluminum bi-material specimen with a sub- interfacial crack. Results obtained from the Fourier analysis technique are in good agreement with those from finite element method.

This paper proposes an iterative phase detection method. It needs only one frame of sinusoidal carrier-fringes pattern, but the demodulated phase is similar to the phase shifting method which needs three or more fringe patterns. In the paper, the basic theory and iterative algorithm are introduced in detail, the computer simulation and experiment results are given out, and the new method is compared with the spatial filter method.

A rarely used fringe demodulation method which uses similar technique to phase demodulation in satellite communications is demonstrated in this paper. The processing is done in the space domain utilizing zero phase digital filters. In this paper, a recursive pole-zero placement digital filter design method has been employed, and the filters have been applied to both 1-D simulated signals and real 2-D images. The results are explained and suggestions to further improve either the quality or speed of the method are also presented. Two methods of producing zero-phase digital filters are explained which is important in preserving the integrity of an image. Theoretical derivation and detailed analysis of the demodulation method and filter design are presented. Images are included as to give a better understanding of the approach. Finally, comments, improvements and comparisons of the method are included.

Signal processing has been used in the ultrasonic nondestructive evaluation (NDE) of materials for a number of years. The time domain analysis of NDE signals includes signal enhancement, deconvolution, matched filtering, etc. and the results can often be linked to physical parameters. Frequency (Fourier) analysis of NDE signals provides information about the major frequency components which may be closely related to the geometry of hidden defects, material properties, etc. It is clear that the use of frequency domain or time domain information alone is not adequate for effective NDE. Recent advances in digital signal processing have resulted in new and effective approaches to joint time-frequency representations that provide more information from the data which may be useful for defect characterization and classification. Among all time-frequency analysis methods, both Wigner distributions and wavelet transforms have been considered for use in ultrasonic NDE. However the full potential of time-frequency representation in ultrasonic NDE is yet to be explored. In this paper, a fundamental analysis of time frequency representations is briefly presented. Several application areas of the time-frequency representation in ultrasonic NDE including geometrical defect discrimination, NDE of bonded materials, sizing problem with geometrical defects, and waveform decomposition are examined in detail.

A new robust and fast method for non-interactive line segmentation of interferograms is proposed. Fringe contours are represented as a set of polygons using a new technique for contour approximation. The method has been developed for application in interferometry with continuously deforming objects. Its application to real-time holographic interferometry in nondestructive testing is shown.

Digital approaches for determination of fringe order and principal stress direction in photoelastic coatings are presented. The relationships between the intensity values and the fringe orders of two wavelengths, and relevant theory and explicit conditions for directly determining the principal stress angles in the range (pi) /2 are derived. The scheme developed allows for the automatic determination of the fringe orders with or without zero-order fringes in the fringe patterns. Test results are reported.

A novel phase unwrapping algorithm for photoelasticity, based on the modulation ordering, is proposed and experimentally verified. The path for phase unwrapping is determined by the intensity modulation in the pixels, on the boundary of the phase unwrapped areas. Therefore, the algorithm is very robust, and in the worst case the error, if any, is limited to local minimum areas.

The orthotropic material which has been developed by authors using copper wires as fiber and epoxy resin as base material is necessary to know optical constants to determine a stress intensity factor by experiments. As a result, it was found that, by applying caustics theory, optical constants could quite easily be obtained in either case of experiments conducted with the specimen held in the air, immersed in liquid, or at the state of frozen stress.

A software SIMFOT has been used to generate isochromatics for some birefringent models. It was improved in order to simulate isochromatics in an infinite plate with a single elliptical hole. Stresses are applied at far boundaries of this plate in the direction of the ellipse minor axis. This minor dimension can be changed as necessary to approximate a line crack by a thin elliptical hole. Images from this plate are compared with images from an infinite plate with a singular circular hole and presents good agreement when the relation minor axis/major axis approaches one. Formulas for the whole stress field in a direct way to be implemented in computer are presented in this paper.

In this study, the stress distributions in single lap joints subjected to static load were measured by photoelasticity, and the effects of Young's modulus ratio of dissimilar adherends and the adherend thickness on joint strength were examined. In addition, the strains were measured when a joint was subjected to an impact load. It is seen that singular stresses occur at the edges of the interfaces. It is also seen that the joint strength increases as Young's modulus of the adherends and the adherend thickness increase. FEM analyses are carried out when joints are subjected to impact loads. The measured results are compared with the numerical results. Discussions are made on the behavior of single-lap adhesive joints.

A sub-millimeter three-component force sensor is developed using silicon microfabrication technology. A polysilicon cross-beam, 300 micrometer by 300 micrometer, with twelve piezoresistive strain gauges integrated on it, is the elastic element of the sensor. The strains detected by the strain gauges are measures of the three orthogonal components of the force applied at the center of the cross-beam. For calibration purposes, electromagnetic forces are generated on an aluminum cross-beam that is suspended over the sensor structure. A 10 (mu) N resolution is obtained for each of the three force components.

We have constructed a laser measurement system for automatic calibration of height setting micrometer. This automation is accomplished by an interactive software tool which performs essential calibration functions. The instrument incorporates a double frequency stabilized laser based on the heterodyne measurement technique. Positioning of height setting micrometer is undertaken by a X-Y stage driven by the servo motors and calibration is performed by combining laser and electronic probe readings. Abbe offset tilting error is eliminated by using the double-path interferometer scheme. The instrument has a capability of measurement range 0 - 350 mm, resolution 40 nm, expanded uncertainty of height measurement better than 0.5 micrometer at the 95% confidence level over the full range. The whole calibration procedure can be completed in two hours making it much more efficient than the conventional method of gauge block comparison. The instrument can also be applied to various linear measurements with high accuracy to reduce the measuring time and to simplify the measurement setup.

This paper is concerned with the experimental study of the ultimate load behavior of steel I-beams curved in plan. Studies were carried out on two sets of I-beams (one set comprised rolled sections while the other set built-up sections). Each beam was subjected to a concentrated load applied at an intermediate point where the beam was laterally restrained. The experimental techniques used in the investigation of the behavior of such beams with special emphasis on instrumentation are described and the results are presented and compared with the results obtained by finite element analysis.

Yarn structure parameters such as twist, hairiness and diameter have an important influence on its mechanical, thermal and dyeing properties. Up to now not any instrument can efficiently measure all these parameters together without destruction of yarn structure. Traditional measuring method involve many problems. For these reasons we developed for the first time a diffraction-reflection method to measure yarn core superficial fiber orientations by electro-optical and computer visualization technologies. Furthermore we also used diffraction method and yarn core shadow to determine respectively hairiness and yarn core diameter in two orthogonal views.

The theory, design, and characteristics of a Phase-locked Electronic Speckle Pattern Interferometry (ESPI) are described. The main principle of the Phase-lock system is to use the characteristics of spatial frequency of the object light to get the information of the phase of the objects' vibration and the disturbance of air. By using the information, we eliminate not only the influence of the objects' vibration, but also the influence of the disturbance of the air. So we can get more stable image of ESPI, and more reliable measurement result.

A speckle technique is being developed for full-field displacement analysis of large structures illuminated by sunlight. Potential applications include displacement measurement of civil engineering and geological bodies. A particularly challenging and interesting application is the study of rock debris-covered glaciers where the surface offers an excellent natural speckle pattern. The large object distances involved in the study of glaciers (up to 6 km) introduce questions regarding atmospheric effects, lens aberrations and resolution, speckle generation and the suitability of sunlight as an illumination source. This paper describes a study of the feasibility of speckle photography in the presence of these factors. It then presents quantitative results illustrating the effect these factors have on the sensitivity and accuracy of the method. In particular we consider; (1) The spatial frequency content of an incoherent speckle image is dependent on the filtering of object spatial frequencies by a transfer function formed from the combined imaging properties of the lens and the atmosphere. Experimental results characterizing the effects of atmosphere on imaging quality are presented; (2) A unique speckle pattern is generated by a certain illumination angle so daily speckle photographs of the glacier surface are taken at a similar time. We consider how much tolerance the technique has to variation in sun angle.

ESPI/DSPI has real time subtraction function and has been used to measure fast deformation. But usually, ESPI/DSPI can not simultaneously acquire two frames which is needed for recording two displacement components (U, V) of in-plane fast deformation. In our experimental setup, the specimen is illuminated by 4 beams symmetrical to normal z. Two beams lie on x-z (y-z) plane with y (x) polarization. By using of a Wollaston prism, two speckle patterns are shifted without overlap. Only one CCD camera is adequate to capture these two patterns as one frame at the same time. An image processing system is used to get fringes patterns as U an V contours real-timely. A strip specimen has been studied by this method.

This paper presents an optical technique for the measurement of surface slope based on laser speckle-shearing interferometry. The technique employs an image shearing camera which records sheared images of an object illuminated by an expanded laser beam. Three exposures on the object are made after the light source is moved in a prescribed manner, resulting in the fringe pattern representing lines of constant surface slopes. In contrast to the previous double exposure method, this method has the advantage of increased sensitivity. The theory of the technique as well as some experimental results are presented.

The issues of fabrication, evaluation and experimental testing of smart composites are discussed. The technology for the fabrication of fiber reinforced polymer composites with embedded fiber optic sensors is developed. Smart composites are produced by a custom built pultruder. It is shown that the mechanical properties of pultruded carbon reinforced composites with and without optical fiber are superior to that of pultruded glass analogue. The embedded optical fibers do not have significant effect on the tensile properties of pultruded FRP, but they deteriorate the shear strength of composites. Polyimide coating on optical fiber results in a good interface between optical fiber and host material; whereas acrylate coating cannot withstand the high production temperature and causes sever debonding of optical fiber and resin. The specific application in view is the use of smart reinforcements for innovative concrete structures.

The smart composite beam featuring the electrorheological (ER) fluids which is designed in this paper is composed of three kinds of materials that are structural material, damping material and sealant material. The elastodynamic frequency response characteristics of smart beam are studied in details by using experimental method. The results demonstrate clearly the ability to significantly change the vibration characteristics of beam fabricated in smart composite by changing the electric field intensity imposed on the fluid domains. Meantime, a control algorithm based on fuzzy-like logic are employed in the active vibration control of cantilevered beam featuring electrorheological fluids. The study results are shown that the beam's structural vibration can be controlled more effectively using the proposed active control rule.

In this paper, some modeling topics on static deflection and vibration control of beam-like structures by using of piezoelectric actuators are discussed. This research is useful in modeling of structures with piezoelectric actuators, and is the basis of the design of static and dynamic control of structures. Furthermore, this research provides the theoretical tools for the design of locations of actuators and other related topics in the field of smart material and structures.

The effects of embedded piezoceramic actuators and sensors on the structural integrity of the host laminated materials have been investigated using finite element analysis and fracture mechanics approach. Double cantilever beam and four point flexural tests were conducted on smart laminates with pre-set cracks to measure the fracture resistances at piezoceramic/laminate and interlaminar interfaces. A two- dimensional finite element code was developed to calculate the stress intensity factors for bi-material interface cracks. It was found that the mode I fracture resistances at piezoceramic/laminate interfaces varied from 3.64 to 4.72 Nmm^-3/2, much lower than both the mode I fracture resistances for interlaminar delamination which varies from 29.6 to 76.8 Nmm^-3/2 for different ply orientations and the mode I fracture resistances (34.8 approximately 53.8 Nmm^-3/2) for cracks inside the piezoceramic actuators. Therefore, the piezoceramic/laminate interface is the weakest interface where debonding may first start when out-of-plane actuation or load is applied.

A new method for measuring 3-D rigid body angle micro- displacements is proposed. Corresponding to the method a laser diode (LD) and a new CMOS image sensor (CIS) are used as a light source and a photodetector, respectively. The method can also be used to measure 1-D or 2-D displacements when required. Moreover, the paper also presents the experimental results, which demonstrate the new method has high accuracy, high processing speed, high reliability, and is easily realized.

Investigations comprising of experimental observations and analytical study have been systematically executed to evaluate the compressive response of a particular composite system which has potential for structural armor applications. The material being a multi-layered thick laminate is a random mode stacking of bi-axial, plain weave S2-Glass/S2-Glass fiber yarns with polyester resin (Cycom 4102) as binder material, thirty two percent by weight. Attention is focused to understand the three dimensional macroscopic behavior of the material subjected to unidirectional quasi-static and dynamic compressive loading conditions using state of the art procedures. Quasi-static (low to medium strain rates) experimental investigations were carried out on an MTS test system while the dynamic response was observed using the split Hopkinson pressure bar test equipment and on a modified Hopkinson pressure bar termed direct disk impact. A comparison of the results of the two setup is presented. The uniformity of the material's response is verified for different sized and shaped specimens. The material's elastic constants, strength and strain rate effects in the region of 10^-5 - 10³ sec^-1 are reported in this paper. The directional failure modes under compressive loading are discussed with the aid of scanning electron micrographs. Based upon the physical construction of the composite, a unit cell representation is presented for analytical modeling. The numerical results of this model is compared to that of the experiment results obtained.

The motion control concerning a free-floating variable geometry truss is discussed. The basic equations for docking control are derived, and to test their validity and explore the practical availability of such a structure in the coming space construction, a docking experiment is carried out. The set-up of experimental apparatus and a VGT model, as well as the control architecture, are illustrated, and various controlled configurations are clearly shown.

X-ray diffraction techniques are increasingly being used for the evaluation of thin film in the microelectronics industries. The techniques use low angle scanning with an X- ray diffractometer. It is capable of determining the structure of the thin film material and its thickness on the substrate. X-ray diffraction techniques on thin film has the advantage over transmission electron microscopy that requires elaborate sample preparation which is time consuming, difficult and artefacts are often introduced during ion milling. In X-ray diffraction, the coated sample can be used without preparation. This paper discusses some recent advances in X- ray diffraction of thin films using parallel incident beam with a wide angle goniometer and a thin film attachment. It also discusses the results obtained on four materials coated with a thin film by chemical vapor deposition.

A motion on sports has been studied by many researchers from the view of the medical, psychological and mechanical fields. Here, we try to analyze a speed skating motion dynamically for an aim of performing the best record. As an official competition of speed skating is performed on the round rink, the skating motion must be studied on the three phases, that is, starting phase, straight and curved course skating phase. It is indispensable to have a visual data of a skating motion in order to analyze kinematically. So we took a several subject's skating motion by 8 mm video cameras in order to obtain three dimensional data. As the first step, the movement of the center of gravity of skater (abbreviate to C. G.) is discussed in this paper, because a skating motion is very complicated. The movement of C. G. will give an information of the reaction force to a skate blade from the surface of ice. We discuss the discrepancy of several skating motion by studied subjects. Our final goal is to suggest the best skating form for getting the finest record.

A systematic study has been carried out to understand the effect of Co (cobalt) on Fe-Ni (Iron-Nickel) alloys. A set of Fe-Ni-Co alloys has been prepared with constant Ni content. The burst temperature of all the alloys were found out within +/- 2 K. It is found out that the burst temperature increases with the initial additions of Co, with further additions, it starts decreasing and finally it does not transform even at liquid nitrogen temperature.

Study aims to elucidate the fracture dynamics of brittle glass fiber reinforcement in a viscoelastic matrix, typical phenomena in the loaded GFRP, by the quantitative source inversion of elastic wave or acoustic emission (AE). We developed a new AE system to measure the out-of-plane displacement of the elastic wave and a source inversion processing to the out-of-plane displacement. The proposed inversion processing, taking into account the wave attenuation and response delay of the P-wave in the polymer matrix, enables us to study the fracture dynamics of various microfractures in loaded GFRP.

In the current photoviscoelastic techniques, a set of multiple data, at least two images under plane polarization at a single instant, are necessary to determine not only fringe order but also principal birefringence direction simultaneously over the whole field of specimen. Therefore, the current techniques cannot be applied to such problems in which the good repetition and reproducibility of experiments are not expected. In order to overcome this type of difficulties in the analysis of time dependent phenomena, the authors proposed a photoelastic method using a white incident light with a set of the three primary colors. When using this method, not only fringe order but principal birefringence direction are successfully and easily determined from a single colored image. Utilizing this method together with photoviscoelastic constitutive equations, time dependent principal stress and strain difference, also their directions are successfully obtained. In this paper, the fundamentals of the white light photoviscoelasticity are described briefly, then a successful application of the method to the analysis of an example of viscoelastic problem is shown. An example problem of a viscoelastic strip having a hole under tension at several temperatures, at which the material shows remarkable viscoelastic behavior, is successfully analyzed.

A prediction method of fatigue strength of polymer composites for an arbitrary frequency, stress ratio and temperature was proposed. The method is based upon the four hypotheses, (A) same failure mechanism for static, creep and fatigue failure, (b) same time-temperature superposition principle for all failure strengths, (C) linear cumulative damage law for monotone loading and (D) linear dependence of fatigue strength upon stress ratio. Flexural static, creep and fatigue tests at various temperatures were conducted in the transverse direction of two kinds of unidirectional CFRP laminates, which are T300/2500 and T300/PEEK. The validity of the prediction method and the applicability of the hypotheses for the flexural fatigue strength in the transverse direction of unidirectional CFRP laminates were discussed.

The aim of this research is to investigate current methods in Linear Elastic Fracture Mechanics for their suitability to predict crack growth in Aluminum alloy 7050 - T7451, when a compressive residual stress field is introduced by an overload. A comparative study has been made on the effect of various levels of tensile overload on the crack growth rate in Aluminum alloy. Experiments were performed on center-cracked tension specimens at various values of range of stress- intensity-factor ((Delta) K). Crack growth measurements are performed using crack propagation gauges and a travelling microscope. The average crack growth rate is used to determine an effective (Delta) K value for each interval using the fatigue crack propagation curve. After the application of overloads, the propagation gauges revealed a period of significant retardation before the crack growth rates returned to their baseline levels. The results from the numerical predictions are compared with the experimental results. The prediction model produces conservative results for both constant amplitude crack growth and overload induced retarded growth.

This paper analyzes fatigue crack propagation (FCP) data obtained from experiments on single-edge notched specimens, prepared from rigid thermoplastic polyurethane. The tests were conducted in tension-tension, at constant R-ratio of 0.1 and a frequency of 0.5 Hz. Two maximum remote stresses were employed: 26.2 MNm^-2 (equalsV0.34 (sigma) _y) and 22.1 MNm^-2 (equalsV0.29 (sigma) _y). The average crack speed at the higher stress was expectedly higher, however, the data plotted in terms of the stress intensity factor range ((Delta) K) according to Paris equation yield two intersecting straight line with notably different kinetic parameters, i.e., slope (m) and intercept (A). This anomaly questions the usefulness of the stress intensity factor as a similitude parameter under linear elastic conditions which has been substantiated in other materials. Plastic zone analysis in both cases established the dominance of plain strain and small scale yielding (SSY) conditions and that requirements for K- dominance were satisfied. It was therefore suggested that K- dominance appears to be necessary, but insufficient criterion for transferability of crack propagation data. Application of the Crack Layer (CL) theory to the same data produced a single value of the specific enthalpy of fracture. Differences in FCP kinetics could be related to the change found in the dissipation coefficient.

The reverse multiplicate technique of moire interferometry is introduced. In this method, shear reverse, carrier wave, multiplicate and optical Fourier processing technique are combined cleverly and applied successfully to the moire interferometry. When the deformed patterns of moire interferometry with carrier wave are multiplied using carrier wave frequency, the deformed information of the specimen are multiplied successfully at same time. As a final experimental result, the moire fringes are multiplied clearly by 16 times, and measuring displacement sensitivity is increased from 0.4 micrometer to 0.025 micrometer. This method is applied to measure in-plane displacement fields around interlayer crack- tip of metal film/ceramic substrate under different thermal loading. From experimental displacement fields, the strain fields around interlayer crack-tip can be obtained as well. The displacement singularity of crack-tip is analyzed. The experimental results show that the displacement singularity of interlayer crack-tip under thermal loading is exponential singularity related with the material properties of the specimen.

Gratings with high sensitivity and high frequency are in big demand in that they are used both as the specimen deformation sensors in the superlattice method and moire interferometry, and as the calibration elements in the field of optoelectronics and matter-wave diffractions. In this paper, photoresist moire gratings with the frequency of up to 6000 lines/mm are fabricated using the coherent light source of argon laser with the wavelength of 457.9 nm. Two techniques are presented. They are: grating fabrication in the refractive medium, and grating frequency multiplication technique. Detailed technologies are given.

Automated machine visual inspection, using non-contact optical means, is a fast and efficient approach for quality control and manufacturing process monitoring. One application is in shape measurement and defect detection which employs a structured light system based on the projection moire method. The fringe patterns of these specimens are obtained by pulsing a single strip of light from a diode laser on the rotating specimens. Defects on these surfaces can be observed when a single strip of light bends proportionally to their depths. The imaging of these fringes is done by a charge coupled device (CCD) camera operating at the time delay and integrating (TDI) mode. By synchronizing the camera scanning speed and the specimen's rotational speed, the 'unwrapped' surface fringe patterns can be obtained and viewed by a computer. The fast Fourier transformation (FFT) technique is used for quantitative measurement of the surface defect.

The surface waves in an experimental water tank were detected by using a CCD camera and an image processing unit. The amplitude and the frequency of these waves were determined by using image processing techniques. They were verified with the measured values obtained by a capacitor measurement technique.

The total amount of light reflected by any portion of a smooth mirror-like surface remains the same before and after deformation. From this observation, if two intensity records of images reflected from the surface of a plate before and after loading are available, the shift of any image point due to loading is estimated by an intensity integration technique (IIT). This enables mapping of surface slope and curvature for the entire plate. The experimental values for slope and mean values for curvature by this technique agree to within 8 - 10% of the theoretical values. If the plate contains a defect the local values of curvature vary sharply. The intensity can be shown related directly to curvature and so the intensity record of the loaded defective plate displays noticeable abrupt changes in the region of defect, thus opening up possibilities for Non-Destructive Testing (NDT).

This paper demonstrates a Fourier transform profilometry for 360 degree shape using TDI camera. Single stripe structured light can be recorded sequentially on one image when the camera is in TDI mode. An extended and deformed grating could be recorded in high speed and high resolution. The deformed fringe pattern is regarded as a fringe pattern in the Telecentric Fourier Transform Profilometry (TFTP), of which a wrapped phase is obtained directly. The unwrapped phase of TFTP gives the extended 360 degree profile without high frequency noise. Theoretical and experimental results are presented.

Automatic non-contacting shape measurement using grid projection methods is often used as monitoring system for protection against disaster. Both high accurate phase analysis of grids and high accurate geometric parameters of the optical system are necessary for accurate shape measurement. We have been proposing the phase shifting method using Fourier transform (PSM/FT) and a method to obtain geometric parameters without influence of lens aberrations. The PSM/FT is most insensitive to noise in phase-shifting methods. In the case of a cylindrical object, a contour map is directly obtained by projecting a grid to the object and gathering the images taken by a line sensor with rotating the object. The phase of the contour map is shifted with shifting the projected grid phase. The shape can be obtained with high accuracy using the above method. In this paper, the principle of the method and an application are shown.

Dynamic inspection of moving objects is a significant task in industrial machine vision systems. Time Delay and Integration (TDI) cameras are being used in some industries for solving problems encountered while using conventional CCD cameras for imaging moving objects. The CCD camera which works in TDI mode is equivalent to a digital drum camera providing possibilities for dynamic inspection on moving objects (either rotating or translating on industrial platforms). Here we report some advances in the application of TDI cameras for inspection and profiling of moving objects. The method is based on the conventional light projection systems which is widely used in industries. The TDI system generates an on-line scanning moire display which could assist operators to identify defects on objects such as dents. Conventional projection systems use mechanical or interferometric type of fringe projections, which is not desirable in the industrial environment. The TDI system makes use of temporal modulation of the projected light which could be easily controlled by a PC or by the output ports in vision systems. In addition to the details of system implementation, we also describe two algorithms for unwrapping the deformation or shape profile of the test object based on fast Fourier transform and sinusoidal fitting on the recorded patterns.

An advanced digital speckle correlation method (DSCM) is presented in this paper. The advantages of this method will not only improve the processing speed but also increase the measuring accuracy. Some mathematics tools are derived and a powerful computing program is developed for further applications. A new feature of the measuring sensitivity of DSCM that can be varied by different amplification of the optical arrangement is first presented. This advantage may be superior to those available in other optical metrology methods like Electronic Speckle Pattern Interferometry (ESPI) in micro-deformation measurements. The applications of strain measurement and nondestructive testing are described and the advantages of DSCM are obvious. Some examples of material behavior measurement and plastic strain measurement are presented. Due to the high sensitivity of DSCM, another potential application in nondestructive testing (NDT) is also described in this paper. From the application examples given, this advanced DSCM proves to be a new and effective optical strain sensing technique especially for small objects or micro-deformation measurements.

Electronic speckle pattern interferometry is used to examine the bearing capacity of a bolted joint with increasing load levels. The bolt is embedded in the wood and is loaded in compression. The observation of the in-plane deformations on wood specimens is obtained in real-time.

A 2-D in-plane displacement sensitive fiber electronic speckle pattern interferometry (ESPI) is developed. With a fiber optics beam splitter of one input and four outputs, two sets of dual-beam interferometrical configuration are constructed in orthogonal directions to determine in-plane displacements completely. A CCD camera with a zoom lens is located at 320 mm to approximately 550 mm away from the specimen to provide adequate space for operation. A testing area ranging from 1.4 mm X 1 mm up to 30 mm X 24 mm can be examined in quasi real-time. In general, the system is capable of determining in-plane displacement and deformation generated by any means. Incorporating with the hole drilling technique, it is currently used to measure residual stress. Two applications are reported in this paper. One is to determine residual stress of a thick cylinder consisting of two concentric circular tubes with interference fit. A simple approach to interpret the value of residual stress from the displacement contour is presented. The other application is to analyze residual stress of recordable optical compact discs (CD-R).

In this paper, a new digital speckle intensity correlation searching technique which is named as 'differential oriented search' is proposed. This method effectively makes use of the distribution characteristics of the correlation functions, which makes the calculating time be considerably reduced. Experimental results shows that, the method presented here is a kind of high speed, high accurate and practical correlation metrology.

In this paper, a phase shifting electronic shearography technique and its application in non-destructive testing (NDT) is described. Electronic shearography or Digital Speckle Shearing Interferometry (DSSI) has found applications as an NDT tool in industrial environments due to its less stringent vibration isolation requirement and simple optical set-up. Moreover, it relies on changes in displacement gradient and so measurements are not masked by overall movement of the specimen. One of the main problems in DSSI is that it is not easy to obtain high-contrast fringe patterns under certain conditions. To solve the problem, an applicable computer- controlled phase shift technique is developed and is shown to yield good quality phase contours of a deformed object. In addition, it allows the displacement derivative at all points on the object to be quantified. This capability leads to the easy and rapid determination of the location, size, and shape of a defect. Experimental results of detection of internal flaws in pipes based on the above system are presented.

In this paper, a new measurement apparatus is designed, constructed and tested. This apparatus is placed in the middle of the circular tube and is suitable for use in the experimental determination of the tube curvature and the ovalization of the tube cross-section. In our experiment, two LVDTs, which are connected with the rotating sprockets of the bending machine, is also used for measuring the magnitude of the tube curvature. The comparison of the amounts of the tube curvature measured by the LVDTs and by the new apparatus is also considered in this study. Due to slight influence by the end condition of rotating sprockets, it is believed that the new apparatus yields the more accurate measurement of the tube curvature than the curvature obtained by the LVDTs.

The knowledge of analyzing a human motion can contribute to the treatment and the prevention of sports injuries or the investigation of welfare equipment. It is important to know the human motion by not only the medical field but the mechanical knowledge. The mechanical knowledge is expected to prevent the sports injuries or to design such as an artificial equipment. Here, we suggest a basic procedure to analyze a human motion from the view of the dynamical knowledge. Although the human body is composed of a lot of element and joint, if the slight movement on the joint such as dislocation and distortion is neglected, the human body can be replaced by a mechanical links system. On this assumption, we analyze an actual simple human motion. We take a picture of a simple arm motion from video cameras. And at the same time, we directly measure the vertical acceleration of the hand by an accelerometer. From the video image, we get the vertical acceleration of the hand with assuming the arm as two-links system. On the process of resolving the vertical acceleration of the hand, we introduce the Fourier series for filtering. Finally, we confirm the propriety of our suggested procedure by comparing the calculated acceleration of hand with the directly measured acceleration.

The dynamic behavior of viscoplastic materials, which are often highly nonlinear in nature, have been extensively investigated during the past thirty years by means of experimental studies. This is perhaps the most reliable means of materials characterization due to the lack of universal theories which are able to describe the materials behavior with a comparable degree of accuracy. Under high strain rates of deformation, e.g . during an impact phenomenon, viscoplastic materials may suffer significant irreversible strains, which are generally much larger than elastic strains. Data of the time history of acceleration are usually obtained from impact tests on samples with uniform dimensions. Stress- strain curves can thus be constructed using double- integrations of the acceleration data to obtain strain values, (epsilon) . However, the accuracy of the stress-strain values often becomes questionable for short-duration tests, e.g. impact tests, since the strain data are obtained indirectly. In this study, strain measurements of some agricultural materials, including apple tissues, as well as cellulosic packaging materials, are obtained using a high-resolution laser displacement sensor with a maximum working range of about 2 cm. The sensor is incorporated to a destructive sample tester, which is found to be very effective in terms of accuracy in direct measurements of the time history of strain, particularly during the initial loading cycle of 1.5 to 2.0 milliseconds (ms) out of a duration of impact of about 4.0 ms, on thin cylindrical fruit samples and square corrugated fiberboard samples with 2 different flute sizes, thus allowing accurate estimation of strain rates, (epsilon) , which are one of the paramount parameters in nonlinear materials characterization.

Surveying deformation of propeller blade under hydrodynamical load is a factual engineering problem when propeller has been developed to a certain stage. This paper develops a photoelectronic method based on subpixel high precision object position surveying. A thin laser beam is incident upon a small reflector adhered to the surveying point on blade, the reflected light is focused on a frosted glass and there appears a facula. The angular deformation of the surveying point causes the facula to move and the motion is detected by an image processing system. The relationship between the motion and the angular deformation under the influence of refraction index is given. The flash method and the facula image grab are also discussed. Finally, angular deformation of 48 surveying points of a highly skewed propeller model of a 2800 TEU container ship under mooring status rotating at 500 and 750 rpm are successfully obtained.

Sports injuries have bothered professional players. Although many medical doctors try to treat injured players, to prevent sports injuries is more important. Hence, it is required to clear a kinematic mechanism of the sport injuries. A shoulder of volleyball attacker or baseball pitcher is often inured by playing motion. The injuries are mainly caused at the end of long head tendon, which is located in the upper side of scapula. Generally, a muscle and tendon have enough strength against tensile force, however, it seems that they are sometimes defeated by the lateral force. It is imagined that the effect of the lateral force has a possibility of injuring the tendon. If we find the influence of the lateral force on the injured portion, the mechanism of injuries must be cleared. In our research, volleyball attacking motion is taken by high speed video cameras. We analyze the motion as links system and obtain an acceleration of an arm and a shoulder from video image data. The generated force at a shoulder joint is calculated and resolved into the lateral and longitudinal forces. Our final goal is to discuss a possibility that the lateral force causes the injuries.

One possible failure of microelectronic devices is due to leakage resulted from imperfect hermetical seal in microchips and microelectronic packages. This paper presents an optical technique for rapid evaluation of hermetics seals. It is based on measuring package deformation with shearography. The package under test is stressed by an external pressure change and the deformation of the test package's lid is measured with shearography. With the pressure change maintained, the lid of a perfectly sealed package will remain deformed while a leaky package will not hold the deformation that can be monitored by shearography. The proposed process of leaking testing is very fast and practical.

In this paper, the evolution properties of micro-deformation field in the copper bicrystals with a symmetric tilt boundary are studied with Digital Speckle Metrology. The micro-speckles are successfully made and the SEM speckle photographs under different loading stages are obtained. The deformation field of the copper bicrystals is quantitatively studied for the first time, and the micro-displacement field and strain field are accurately calculated. The experimental results show that, the evolution characteristics of the displacement field is obviously different from that of the macro-displacement field. These results provide some basic experimental data for the study of micromechanics.

There is current interest, especially in the industrial sector, to use the digital speckle pattern interferometry (DSPI) technique to measure surface stress. Indeed, many publications in the subject are evident of the growing interests in the field. However, to bring the technology to industrial use requires the integration of several emerging technologies, viz. optics, feedback control, electronics, imaging processing and digital signal processing. Due to the highly interdisciplinary nature of the technique, successful implementation and development require expertise in all of the fields. At Baptist University, under the funding of a major industrial grant, we are developing the technology for the industrial sector. Our system fully exploits optical fibers and diode lasers in the design to enable practical and rugged systems suited for industrial applications. Besides the development in optics, we have broken away from the reliance of a microcomputer PC platform for both image capture and processing, and have developed a digital signal processing array system that can handle simultaneous and independent image capture/processing with feedback control. The system, named CASPA for 'cascadable architecture signal processing array,' is a third generation development system that utilizes up to 7 digital signal processors has proved to be a very powerful system. With our CASPA we are now in a better position to developing novel optical measurement systems for industrial application that may require different measurement systems to operate concurrently and requiring information exchange between the systems. Applications in mind such as simultaneous in-plane and out-of-plane DSPI image capture/process, vibrational analysis with interactive DSPI and phase shifting control of optical systems are a few good examples of the potentials.

The measurement of phase in Digital Shearing Speckle Interferometry (DSSI) is a challenging problem because of the inherently noisy nature of shearing speckle interferograms. Accurate phase measurement depends on having a high-precision imaging system, a finely-controlled phase-shifting technique and good algorithms. In this paper, two selected algorithms used for carrying out phase measurement in ESPI (Electronic Speckle Pattern Interferometry) are applied to phase measurement in DSSI. The components and requirements of the high-precision imaging system developed to improve the recording quality of shearing interferograms are discussed. A new precisely-controlled phase shifting method developed to reduce systematic measurement error is also described. Experimental results are presented to illustrate the method.

It is well known that there still exist several difficulties in the analysis of contact stress or strain around the region near contact because of unexpected irregular boundary data obtained by the current experimental techniques, such as Moire interferometry, in spite of highly accurate and precise information of continuous distribution of fringes inside a body. In order to overcome the type of difficulties, a combined technique with Moire interferometry and thin-coating photoelasticity is discussed to analyze stress/strain near a contact region, utilizing their features in either macro- or micro-scopic analysis of displacement and strain distribution the surface of a body.

This paper presents a new method to measure cyclic strain with no contact using metal foil gauges and laser speckle sensor. When a metal foil (such as aluminum, copper, nickel etc.) is pasted on a specimen and the specimen is loaded cyclically, slipbands are produced on the foil surface by fatigue. The occurrence of the slipbands is dominated by the strain amplitude of the specimen surface and number of the loading cycles. Thus the fatigue strain of the base metal can be estimated by observing the surface change of the foil. The method in this study is based on observation of the change of laser speckle pattern depending on the surface property change of the foil caused by fatigue. This method is intended to make a non-contact strain measurement by the application of the laser speckle technique for the detection of the surface change.

Foam-adhesive bonding is a common fabrication process in the aerospace, the automobile and the electronic industry. During service, the change with time in the behavior of components fabricated by this process is often caused by degradation of the foam layer within. As it is impractical, and at times impracticable, to dismantle the component for the purpose of testing and examining the foam layer, the need arises to develop methods of assessing the properties of the foam layer in situ. Many foam-adhesive bonded components comprise segments of strips bonded along their lengths to a rigid support. Additionally, these strips are secured with mechanical fasteners to prevent detachment from the support should the bonding fail. In this paper, a method is proposed which permits estimating the stiffness of the foam layer when the adherend (i.e., the strip) is subjected to point loads representing the forces exerted by the fasteners. The surface of the adherend is of mirror-like finish, as is found in the disk-drives industry. From the Moire fringe pattern generated with the use of the mirror-image method, the deflection of the adherend due to the point loads is deduced. Treating the foam layer as of the Winkler type, the magnitude of its stiffness is iterated using the theory of beams on elastic foundation.

Using advanced laser mask projection methods it is possible to manufacture miniature complex 3D structures in polymers and ceramics for sensor and micromechanical device prototyping or mass manufacture. Subtle movements of workpiece and mask (separately or together) during processing allow complex devices to be realized. Multilevel sensor structures can be constructed using lamination techniques. The full capabilities of laser micromachining techniques are explained in detail and an examples of novel 3D structures made by laser machining are shown.

The comb structure is a popular microstructure used in microelectromechanical devices. As a result, it is essential to understand the physics of the comb structure by understanding the levitating force associated with the comb structure. The design of the comb structure can be optimized by minimizing resonator friction and maximizing harmonic work per cycle. The comb structure is fabricated using the high aspect ratio process so as to produce stiffer comb fingers as well as to increase the capacitance between the comb fingers.

The effects of temperature and moisture on the dynamic moduli of thick S2-glass composite beams were investigated. Unlike most of the previous studies in which elevated temperatures are concerned, the present investigation concentrates on the influence of low temperature on composite materials. By supporting the sample in a free-free configuration and subjecting it to impacts, its natural frequencies can be measured. Samples having different moisture contents at different temperatures were then tested to disclose the frequency dependence on the environmental conditions. Based on the measured frequencies, an inverse calculation scheme was then used to characterize the longitudinal Young's modulus and the transverse shear modulus of the sample. The moduli thus found are insensitive to the measurement errors rendering the technique a possible supplement for conventional static tests. Eventually, incorporation of the aforementioned frequency data into the inverse calculation scheme yields valuable information regarding the hygrothermal effects on the dynamic moduli of composite materials.