Recent developments of SIEM for micro/nano measurements are presented including applications to composite interphase, crack tip deformation, heart mechanics, and electronic packaging. A new technique FDS which uses fractal dimensions to assess composite damage is also described.

A dynamic process of deformation in a tensile experiment of an Al-alloy sample was analyzed by a newly developed ESPI system. In a plastic deformation state after yielding of the mailer, propagating strain concentrated band which corresponds to serration by Portevin-LeChatelier effect was observed. In the band, repetition of increasing and decreasing of number of fringes was observed. The phenomenon means the wavy propagation of a plastic deformation state accompanied by localized strain pulsation. Phase analysis of dynamically deforming object was also done.

In the strain field measurements especially in large strain field measurements, usually the correlation coefficient values obtained by the digital speckle correlation method are very low due to the relative pixel movement of the subset. Thus the measuring error will be increased. A primary method, that is called compensation algorithm, is introduced for improving the correlation coefficient. A flow scheme with the compensation algorithm of our software is developed and some improving techniques for reducing the calculation error are discussed in the paper. After getting a set of displacement data with high correlation, a de-noise wavelet processing is adopted. It is obviously that the measuring accuracy of the strain field is much better than before. The error is 0.1 to 0.3 pixels less than before. A strain field of testing experiment is performed with this compensation technique. The correlation coefficients can increase from 0.70 to 0.99 and that will be of much benefit for the improvements of the measuring accuracy.

A general problem in optical metrology is to measure a deformation field when this field is added to a translation or a rotational motion. Methods like Speckle Photography (SP) do handle large rigid body motions but the result might be of too poor accuracy to resolve the deformation field. Interferometric methods on the other hand might measure the deformation field but the bulk motion makes the fringes disappear. By combining digital speckle photography, with Speckle Interferometry, or with shearography, such measuring situations can be mastered.

The point by point measurement of in-plane displacement was conducted by the point wide filtering approach of speckle photography. The experiment was conducted on the compact normal and shear specimen made of homogeneous and dissimilar material subjected to various kinds of mixed-mode loading. Then, stress-intensity factors of asymptotic solution derived by Sun and Jih were estimated using the displacement data obtained from speckle photography by the least squares method. The contour diagrams of stress and strain obtained by using the raw displacement data of experiment remarkably differed from those obtained by the finite element analysis (FEA). However, the stress and strain obtained by the present analyzing system were very similar to those obtained by FEA.

The classical digital speckle pattern, or digital image, correlation method of deformation measurement is based on gray level correlation between unformed and deformed digital images. Since the pattern of artificial random speckles and the natural texture have fractal characteristics, and their fractal dimensions represent both gray and morph information, a fractal correlation method of displacement measurement is developed in this paper. The in-plane displacement field of a body can be acquired. In order to verify the validity of the new method, an experiment has been designed and the results have been compared with those tested by gray correlation method. The calculation speed is over 20 times fast than the digital image correlation method. The results how that its precision is less than 0.05 pixels.

In order to avoid local deformation and stress concentration at contact points between the extensometer and the specimen surface in a strain controlled fatigue test, the digital image measurements system was adapted to measure the displacement of the specimen gage during a fatigue test. Capability of the digital image system for the strain- controlled fatigue testing was studied by preliminary experiments. Low-cycle fatigue tests with various ranges of strain were conducted on solder materials at a constant temperature of 20 degrees C. The effect of variables in the digital image measurement system on the accuracy and the reliability were discussed. The results confirmed that this system was capable to measure the displacement for strain- controlled fatigue testing.

The quasi-static loads experienced by large spacecraft structures during launch are generally simulated by static loading for qualification purpose and often specific to a spacecraft. A number of important aspects related to the development of a generic static test facility that has been developed at our laboratory are discussed with illustration of test performed on a typical spacecraft structure.

A shearing interferometer which comprises a beam displacer, polarizer, and CCD camera is prosed in this paper. The shearing plate of this interferometer is the bam displacer which splits a laser beam passing through it into two components that are laterally separated, parallel, and orthogonally polarized. Thus, as these two components propagate through the polarizer and then to the CCD camera, s hearing interference pattern is generate and recorded. The optical setup of this interferometer is described, the results show that this interferometer can be adopted for inspecting the wavefront of a laser beam, the strains of a specimen grating, and the strains of a diffusion object. Three experiments were carried out in this paper. The first was to determine the radius of curvature of a spherical wavefront, the second was to measure the strain of a circle diaphragm bonded with a grating, and the third one was to detect the strain of a square diaphragm with diffusion surface. Experimental results confirm the validity and applicability of this interferometer.

Attitude and position monitoring system of the cube corner prism used in a n optical interferometer, which is originally developed for our Levitated Superconductor Experiments, is discussed. In general, the point to be measured by an optical interferometer does not coincide with the measurement point such as the optical center of the cube corner prism used in the optical interferometer. If the attitude of the object, on which the cube corner prism and the point to be measured exist, changes during the measurements, this result in the measurement error. Using het developed system, the attitude an the position of the cube corner prism in an optical interferometer is monitored from a distant point. Further prospects in applying this developed method to a general interferometer are discussed.

The residual stresses induced by using self-drilling screw on polycarbonate plates were investigated by incorporating the photoelastic method and finite element method (FEM). Different types of screw lead to different results, which provide the boundary conditions needed in the numerical simulation. By changing the two parameters, the FEM results can be matched well with the experimental results.

In this paper, a simple method is described for the measurement of small angles of rotation of a flat surface using a circular optical grating, which may be generated and projected onto the test surface using either a standard Michelson interferometer or a computer-controlled LCD projector. In view of its availability in most laboratories, a Michelson interferometer is used in this paper. The diameter of the grating that is generated can be easily magnified or be reduced to suit the size of the test surface. With circular grating, the angular rotation of both diffuse and specularly reflective surface about any axis of rotation can be measured from the distortion of the grating. The distorted grating that is diffracted from a specularly reflective surface may be recorded in two different ways using a CCD camera. In the first method, the distorted grating is recorded off the m mirror surface as though it were a diffuse surface. In the second method, the distorted grating is recorded off the miro surface as though it were a diffuse surface. In the second method, the distorted grating is specularly reflected onto an opaque screen and the CCD camera subsequently records the grating image off this screen.

In order to characterize fatigue performance of a material by temperature change, rotary bending fatigue tests were performed for an aluminum alloy 2024 and a structural steel. The temperature changes of these specimens were successively measured using IR thermometer. The test were performed at a rate of 2850 rpm in air at room temperature. The stresses below proof stress or yield strength were applied to aluminum alloy specimens and structural steel specimens respectively. Results are as follows: During fatigue test, between both materials, obvious difference in temperature change to stress sequence was observed. Temperature change of the aluminum alloy specimen was influenced by the stress and the number of cycles applied. So the temperature change indicates that fatigue damage of the aluminum alloy cumulates non-linearly to the number of cycles. On the other hand, as the temperature change of the structural steel depended only on stress and not on number of cycles, it indicates that fatigue damage of steel cumulates linearly to the number of cycles.

Split Hopkinson Pressure Bar (SHPB) has become a frequently used technique for measuring uniaxial compressive stress- strain relationship of various engineering material sunder high strain rate. By using the strain measurements on incident and transmit bars, the average stress, strain and strain rate histories within the specimen can be evaluated by given formulas based on 1D wave propagation theory. However, the 1D wave propagation assumption in pressure bars cannot been assured when large diameter or viscoelastic bars are used for testing brittle or cellular materials. One of the important error sources comes from the long time shift distance between the gauge position and the bar/specimen interface. This paper presents a modification of SHPB set-up based on wave separation technique and dynamic Saint- Venant's principles, which can greatly cut off the time shift distance and the pressure bar length. The proposed method is validated using numerical test based on FE simulations.

A method for generating and measuring varying force by means of levitating a rigid object is discussed in this paper. The varying force is directly and accurately measured using an optical interferometer as the initial force acting on the inertial mass. The performance of the three-point bending tester based on the method is investigated by conducting several sets of three-point bending tests for aluminum bars. The future prospects of this method are discussed.

The tensile mechanical behavior of a short carbon fiber filled liquid crystalline polymer (LCP) composite, Vectra A230, was examined under static extension and dynamic loading at three temperatures. Dynamic tension was applied using a pendulum-type tensile spilt Hopkinson bar device. Specimens fabricated according to both the mould flow and transverse directions were tested. The stress-strain curves at various strain rates and temperatures were determined and found to be sensitive to strain rate as well as temperature for both types of specimens. With reference to the properties of pure LCP, mechanical anisotropy and fiber reinforcement effects were characterized and are discussed. Failed specimens were observed suing an optical microscope. Deformation and failure mechanisms in the microstructure of the LCP composite were studied to understand the effects of strain rate and temperature on material strength and failure strain.

Tensile and compressive stress-strain response of two types of TPOs and graphite-epoxy composites are investigated at strain rates in the range 0.001/s-1000/s. Specimen strain in the low strain rate regime 0.001-100/s was determined using an optical extensometer in conjunction with standard MTS machine. Tensile test at high strain rate were performed on newly developed tensile version of All- Polymeric Split Hopkinson Bar. Tensile TPO specimens in the dog-bone configuration are placed in specially designed grips fabricated from nylatron. Compression response of TPO specimens at high strain rate is determined using 25.4-mm diameter aluminum bars. Peak compressive stress increases from 10 MPa at a strain rate of 100/s to 35 MPa at a strain rate of 1000/s. Preliminary data on high strain rate tensile response of graphite-epoxy and graphite-peek composites are presented. These data are intended to develop a material model incorporating strain rate sensitivity for TPOs and to be used in car crash simulations.

In recent years polymer alloys or polymer blends have become one of the most widely used material in engineering application. To improve the reliability of the materials, extensive studies are required on their fracture behaviors under general loading conditions. Polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blends were selected in this research to examine the fracture behavior of po9lymer alloys. PC/ABS is the polymer alloy of PC and ABS and its characteristics varies with volume fractions of two components. In this study, fracture test under mode I and mixed mode loading was conducted and fracture behaviors were observed. At a certain value of mixed mode loading ratio with high mode II components, crack due to shear type fracture initiates at the initial crack tip. Fracture toughness and the appearance of shear type fracture depends on blending ratio of PC and ABS. It is suggested that these tendencies related to morphology of PC/ABS blends. Fracture resistance increase under mixed more loading with lower in mode II component, while it reduces with the appearance of shear type fracture.

To analyze fringe patterns, frequency and phase analysis of fringes becomes popular. It provides accurate results and automated processing. In this paper, the theories of the frequency and phase domain methods such as the Fourier transform method, the wavelet transform method and the phase-shifting method are proposed for photoelastic fringe pattern analysis. The applications of these methods are described.

A new whole field methodology is proposed for stress separation using only isochromatic data collected over the field for normal and oblique incidences. For this purpose, a non-linear least squares approach is adapted to process the data. Numerical experimental is carried out on a disc under diametral compression to show its validity.

Although photo elasticity technique has recently become sufficiently refined due to use of digital image processing, the difficulties with an appropriate accuracy, especially in integrated photo elasticity still persist. Specifically, there remain as problem with a precise imaging of three optical parameters describing a general 3D model in the regions, where mutual interference of these parameters leads to deteriorated accuracy. In this paper it is shown how to improve imaging accuracy of PSA Fourier polarimetry method, recently suggested for use in integrated photo elasticity. This can be overcome by incorporation of a compensator into the polarimeter arrangement. Use of the compensator provides equally precise imaging of birefringence through the whole possible range of phase and ellipticity angle values. Also, it allows for determining a sign of phase.

In this study, the authors propose a method for determining not only the secondary principal stress difference, but also its direction, using 3 image data obtained in various of polarization angles of incident light. As an example, a sphere under diametrical compressive load is analyzed to determine both the secondary principal stress difference and their directions, with or without rotation of the principal birefringent axis along the light path. The results show good agreement with theoretical/computed analyses.

High speed photographic system like the image rotation camera, the Cranz Schardin camera and the drum camera are typically used for the recording and visualization of dynamic events in stress analysis, fluid mechanics, etc. All these systems are fairly expensive and generally not simple to use. Furthermore they are all based on photographic film recording system requiring time consuming and tedious wet processing of the films. Digital cameras are replacing the conventional cameras, to certain extent in static experiments. Recently, there is lots of interest in development and modifying CCD architectures and recording arrangements for dynamic scenes analysis. Herein we report the use of a CCD camera operating in the Time Delay and Integration mode for digitally recording dynamic photoelastic stress patterns. Applications in strobe and streak photoelastic pattern recording and system limitations will be explained in the paper.

The present paper demonstrates the successful application of the photo viscoelastic technique using elliptically polarized white light to the stress field evaluation of the crack growth in a viscoelastic strip. Using the proposed technique, which can determine both iso chromatic and iso clinic parameters simultaneously from a single color image, the time-dependent stress intensity factor extended for linearly viscoelastic materials is evaluated from the experimental results using a method based on least-squares. The result show that the value of the prosed critical stress intensity factor for fast crack growth may be considered as a characteristic property of the material under monotonically increasing load.

Effects of image compression on digital specklegrams are studied in order to solve storage problem of the speckle photography. By measuring a sharpness of correlation peak computed from the compressed specklegram, information quality of the specklegram is studied. The preliminary study shows that the specklegram could be compressed about 12 times smaller without distorting its information content.

This paper presents a method for determining the slope and period of oblique and equi-spaced fringes by fringe pattern matching. In the method, two pairs of image patches in two different regions of a fringe pattern are selected for fringe pattern matching, and the phase shift between the fringes in the two selected regions of the fringe pattern is obtained from the two mismatch curves which are calculated from the mismatch function in fringe pattern matching. The slope and period of oblique fringes can be therefore determined using the distance between the two selected regions, the phase shift between the fringes in the regions, and the period of mismatch function with a subpixel resolution. The effect of image patch size on the determination of the slope and period of oblique fringes is also discussed based on a statistical analysis. The statistical analysis, computer simulation and experimentation results have shown that the determination of the slope of oblique and equi-spaced fringes by fringe pattern matching has the advantage of averaging noise due to the region-based matching.

In this paper, the authors make some researches on the method of manufacturing composite models to imitate different geological structures and on the equations of eliminating the freezing 'cohesive stress'. Also, an exact solution of 3D photo elasticity and practical application in engineering are given of solving, by oblique technique, the individual amount of the stresses at points of the composite model.

We present a special scheme of projection moire topography that is particularly intended to implement out-of-plane displacement measurement in non-contact mode for experimental analysis of static deflection and dynamic vibration. A pair of gratings constitute the primary component of measurement; one is for protection a line pattern on the target surface while the other is for generating moire fringes by imaging to itself the deformed line pattern projected on the target. For the whole measurement, two sets of four pairs of gratings are used in sequence, which offer four different phase shifts in dual frequency mode in the generation moire fringes. The fringes are captured in real time by a CCD camera and processed within an IBM PC by incorporating phase-shifting fringe analysis, so that 3D coordinates of the target surface are finally obtained by unwrapping the measured phases of fringes.

The AFM scanning moire method was proposed to measure the in-plane deformation in the micrometer scale. The principle and technique for measuring in-plane deformation using AFM scanning moire method are described. This method was applied to measure the thermal deformation in a quad flat pack (QFP) electronic package at 100 degrees C. The normal strain component (epsilon) _y and the shear strain component(gamma) _xy near the die in the QFP package were measured.

Here a new flash phase-shifting method has been prosed. In this method, the phase difference between three consecutive Moire images is achieved by changing the illumination angles. A theoretical derivation is presented, and certain formulas are obtained to calculate 3D information of the measured object. The special phase unwrapping algorithm connected with this phase shifting method is also solved out. At last, experiment result have been given to compare with theory derivation.

The deformation mechanism and the surface strain non- uniformities of the carbon fiber braided composites in low temperature cycle ranged from 0 degrees C to -40 degrees C by moire interferometry was described. A series of moire fringe patterns which reflect the thermal strain field of the braided composite are recorded. The relations between the fiber braided architecture and the degree of inhomogeneity of deformation are analyzed by the fringe waviness and the variation of fringe density. From the moire fringe patterns, it is obvious the higher shear strain was occur in the regions between braided yarns and a significant thermal expanding effects in fiber longitudinal and vertical direction. The strain distributions at 0-40 degrees C were presented and that the large strain nonuniformity as displaced and the maximum strain is 11 times higher than the average strain. From the experimental study moire interferometry is an effective research tool for the braided composite material.

Moire interferometry is employed along with the hole drilling technique to determine residual cure stresses in symmetric cross poly graphite epoxy laminates. Traditional moire interferometry set-up using two collimated angle beams was employed to provide the virtual reference grating while a cross grating with a frequency of 1200 lines per mm was replicated on the specimen surface. Holes of different depths, each one penetrating one additional layer of the laminate, were drilled using a high speed air turbine drill to relieve the stresses in each layer sequentially. The strain distribution around each hole was computed from correlation of the undistorted carrier fringe pattern with the distorted fringe patterns around the holes. The measured strain distributions are compared to residual strain distributions predicted by classical laminate theory.

Different techniques are available for macro- and micro- topometry. The methods are basically known but their industrial implementation requires robust measuring systems, where calibration is an important necessity. Different techniques will be presented. New elements such as liquid crystal displays and micromirror devices are available leading to new applications to be discussed. Combinative methods and integration in measuring systems becomes interesting. The state of the art and new developments will be presented. Together with calibration for 3D-shock or vibration analysis an object shape measuring systems will be directly combined with a vibration measuring system.

Comparing with general optical fiber sensors performing localized measurement, the distributed optical fiber sensors measure along the length of an optical fiber and thus they have a large measuring range. This implies that the distributed optical fiber sensors are very effective in the health monitoring of large structures. The Brillouin scattering is one of the inelastic scatterings in optical fibers, and it can be used in the measurement of strain and temperature with the Brillouin frequency shift. The surface- mounting with epoxy is generally used in the application of optical fiber sensors to monitoring structures. This is also used in the integrity monitoring of structures with the Brillouin-scattering distributed optical fiber sensors. In this research, the Brillouin-scattering distributed optical fiber sensors, which are mounted on the surface of a structure with epoxy, was evaluated with the finite element method. From the analysis results of the strain transfer through the structure, epoxy adhesive, optical fiber coating, cladding and core, the strain transfer rate was calculated. By using the strain distribution, the influence of the epoxy free-end was also studied.

This paper presents analysis and simulation results describing the feasibility of a modified distributed optical fiber strain sensor whose principle of operation is based on the frequency-modulated continuous-wave reflectometry technique. The sensor consists of a frequency-swept laser diode and an unbalanced two-beam interferometer. In this system, the test arm comprises a number of single-mode fibers, which at as the sensing fibers, with a mirror at the far end and mechanical splices as the connectors, as well as the reflectors. The strain variation of the sensing fiber is measured by demodulating the phase shift of the beat signal using a heterodyne signal processing system, and therefore the requirement of a high precision temperature control of light source can be eliminated in this way. The measuring resolution of ht strain was found to be inversly proportional to the optical path difference between the reference are and the test arm. Experimental results showed that the theoretical value and accuracy were achieved.

We demonstrate a high-sensitivity, relatively simple and inexpensive technique for interrogation of fiber-Bragg- grating sensors, where the signals from the sensor are resolved with a fiber-Bragg-grating filter tuned by a cantilever beam. We achieve a wavelength resolution of 0.002nm, which corresponds to a strain resolution of 1.7(mu) (epsilon) or a temperature resolution of 0.03 degrees C.

This paper describes an optical system for high temperature strain measurement by using quartz optical fiber, super long working distance microscope and digital image processing techniques. In this system one ends of the quartz optical fibers are arrayed in a small area on the specimen surface and the other ends are illuminated by a laser beam. The fiber ends on the specimen surface from the spot array. The small optical spots on the specimen are tracked by a CCD camera and the images are processed by digital image processing software. As the diameter of each quartz fiber is only 100 microns the fibers can be arrayed in a tiny area. The local strains were determined by measuring the variety of relative distance between two spots. The measurement results of local creep strain on the welding joints of 15CrMo and HK40 at 850 degrees C are obtained.

A PFOS for monitoring and detecting damages in aluminum specimen has been demonstrated. It has been shown that PFOS can be used to monitor the development of cracks and predict residual load on aluminum structures. The experimental result obtained is very consistent and the sensor is immune to temperature changes and electromagnetic interference, as it does not require a reference are more accurate for damage detection. Some of the features such as low cost, durable, light weight and real-time applications of PFOS have been highlighted.

Initially developed for applications in the aerospace industry, fiber-optic Bragg grating sensors (FBG) have attracted attention in the civil engineering community. The interest in FBG sensors has been motivated by the potential advantages they can offer over existing sensing technologies. They are, immune to electromagnetic interference, small in size and can be easier to install than traditional electrical resistance strain gauges. They can also be multiplexed, that is, a single fiber may have more than one change. Although field test of FBG sensors have been reported in literature, there is a dearth of information on their installation procedures, their precision in quantifying strains of concrete structures, and robustness requirements for embedment in concrete structures. In particular the harsh environment during the construction of concrete structures is a great challenge in the installation of these fragile sensors. The paper reports on our experiences with FBG sensors in concrete structures. FBG sensor have been sued to quantify strain, temperature and to capture vibration signals. Th result of these studies indicate that, if properly installed, FBG sensors can survive the sever conditions associated with the embedment process and yield accurate measurements of strains and vibration response, so it is possible to benefit from their potential advantages.

Microscopic digital image metrology system, which is a combination of a long-focus microscope and a digital image measuring device, is developed for study in the mechanics behavior of the interphase of bimaterials. The natural texture of a specimen's surface is though as a carrier of deformation information and is analyzed to obtain the displacement field in each step, strain field and their real-time variation of the interphase. The resolution of the micro-metrology system is 10 nm. In this paper, the micro- metrology system is employed to investigate the mechanics behavior of the interphase under thermal impulsing. The experimental results that the interphase are the main factors of affecting the mechanics characteristic of the whole composite structure.

A new ultra-precision instrument is designed and fabricated for measuring the mechanical compliance of Micro-systems. The apparatus was based around an inverted optical microscope. Attached to the microscope stage is a compliant mechanism activated by a PZT actuator incorporated with a micro-stepper DC motor capable of generating discrete micro- steps of less than 1 nm and a traveling distance up to 10 mm. A measuring system with a force resolution better than 10 (mu) N and a maximum force capability of 0.1N will be attached to the stage. In its final form the tester have a force and displacement resolution of 10 (mu) N and 1 nm, respectively. For viewing the micro-system under deformation, a high-resolution CCD camera connected to the microscope allowed to acquiring the images. The preliminary measured compliance of a well-defined micro-system is presented to be reasonable.

The basic theory behind microscopic electronic holographic moire is presented. Conditions of observation are discussed, and optimal parameters are established. An application is presented as an example where experimental result are statistically analyzed and successfully correlated with an independent method of measurement of the same quantity.

Current trends in the miniaturization of MEMS require the use of increasingly smaller components. MEMS has already offered challenging opportunities for improving test techniques. In this paper we have developed a technique for testing deflections of a micro-beam in an accelerometer under point-force load. The technique is based on light interferometry. A collimated monochomatic light is direct ed into an air-wedge consists of an optical flat and a micro- beam. A long distance microscope with a CCD camera is utilized to capture the interference fringe pattern which results from recombination of two-beam reflected from the optical flat and the micro-beam. The resulting fringe patterns are analyzed by the use of FFT and deflections of the micro-beam are obtained. The experimental results show that the proposed technique is relatively simple and accurate, and is a potential method for conducting measurement on micro-components.

IN this paper, a novel compact strain sensor using grating diffraction method this method is presented. The grating generally with a frequency of 1200 lines/mm attached on the surface of a specimen is illuminated by a focused laser beam. The centroids of diffracted beam spots from the gratin is automatically determined with two position-sensitive detector (PSD) sensors connected to a personal computer. The shift of diffracted beam spots due to the specimen deformation is then detected. The influences of noise sources and system geometry on system performances, such as sensitivity, spatial resolution, strain range and measurement linearity are discussed. Strain sensitivity of 1 micro-strain can be achieved. The spatial resolution, for strain measurement of 0.4 mm is attainable. The system can be used for continuous measurement and for both static and dynamic test.

A double cleavage drilled compression (DCDC) specimen has been analyzed by the boundary element method (BEM). At the same time, the DCDC specimen of FRP composites was proposed and used to evaluate the interfacial behavior and fracture energy in CFRP model composites. As a result, it was confirmed that the DCDC specimen had a mode I stress distribution for the hole offsetting displacement of b equals 0, which was of a symmetrical hole, while it had the mixed- mode stress distribution for b does not equal 0. The approach of calculating the interfacial fracture energy was established by using both of experimental results and analysis. Furthermore, the bridging fiber DCDC specimen was proposed and the effect of bridging fibers on the loading phase was made clear. It was shown that the DCDC test was a useful method to quantitatively evaluate the interfacial behavior of fiber/matrix in composites.

In this paper, the toughness of copper-bismaleimide traizine interface is determined using the peel test. Invoking energy balance and using the peel force and the extension of het strip, the total work per unit area of fractured interface is calculated. The analysis takes into consideration the elastic energy stored in the peel arm and the plastic deformations due to stretching and bending of the peel arm. Several tests were conducted under ambient conditions. Test were also performed on samples that had been precondition at 85 degrees C and 85 percent relative humidity. Results from both sets of tests showed that the interfacial toughness was in the range of 320 to 420 J/m².

Ceramic thermal barrier coatings (TBC) are increasing applied to high temperature structures such as gas-turbine components. Spalling is one of serious damage mode of TBC, which includes fatigue crack initiation and propagation along the interface. In the present study, a new test method for realizing fatigue crack initiation and propagation along the interface has been successfully developed. From the results of fatigue crack growth test and boundary element method analysis, it has been found that is K₁ equals (root) K₁² + K₂² a suitable parameter for evaluating crack growth behavior of an interface crack under mix mode.

The push-pull low cycle fatigue test were performed under the strain-controlled condition and the step height formed at grain boundary, which is precursors of crack initiation, was measured in annealed copper using AFM. Then the step growth behaviors in cyclic loading process were compared with the one obtained from fatigue test performed under stress-controlled condition. In the early fatigue process, grain boundary step was not formed under strain-controlled condition. In the early fatigue process, grain boundary step was not formed under strain-controlled condition, whereas steps with 20-50nm in height were generated under stress- controlled condition. The critical step height at grain boundary at crack initiation H_c was quite large under strain controlled condition as compared with the one under stress controlled condition.

The paper aims to illustrate the relevant use of IR thermography as a non-destructive, real-time and noncontact technique (a) to observe the physical processes of damage, fatigue and failure on metallic specimens subject to fatigue testing, 9B0 to detect the occurrence of intrinsic dissipation and (c) to evaluate the fatigue strength in a very short time. In addition, this IR thermographic technique readily describes the damage location and the mechanisms of structural failure.

Computer vision inspection systems are widely used for on- line inspection and quality control to improve the finished product quality and lower the costs. In this study, a carrier grating is used to carry spatial information about defects. To demodulate the regular/irregular fringe information, a Gabor-filter demodulation method is proposed, which is better for automatically detecting and localizing fringe distortion and hence demodulation method has been implemented for testing some wineglass samples. Using Gabor channel filters the feature images from global to local over those samples regions are extracted and utilized to classify them into good and bad.

A preliminary study on the susceptibility of various iron- boron-silicon metallic glass to stress-corrosion cracking has been conducted. Testing was carried out on thin metallic ribbons at room temperature.

Adhesive bonding has been accepted as an important process in the manufacturing and repair industries. However, the tendency of delamination at the bonded region due to improper bonding procedures, and unfavorable loading conditions and service environment has necessitated development of reliable inspection techniques for ensuring the structural integrity of these bonded structures. Optical inspection techniques have, over the last three decades since the invention of the laser, gained wide acceptance because they are non-destructive and non-contacting, and accurate measurements in the order of light-wavelengths may be obtained very rapidly. Optical flaw-detection generally requires the application of a load-increment on the structure, the response of the illuminated surface of the structure is then compared with that of a non-defective structure. The load-increments used are in various forms, such as vacuum stressing, heating, static mechanical loads, and steady-state mechanical excitations.

Shearography, which enables direct measurement of surface slopes under lax environmental stability, is a practical optical tool for measurement and inspection. When applied to flaw detection, conventional shearography requires recording of two sheared-images of the test structure using an image- shearing camera - one before and another after the application of quasi-static load-increment. The resulting phase-change will be perturbed at the region where a flaw is present, when compared with that of a defect-free identical test structure. With time-average shearography, the test object is subjected to vibration excitation, and this is useful for inspection open-boundaries delaminations. A major drawback with the use of single excitation frequency is the need to vibrate the test object within an appropriate frequency range, as otherwise the test data obtained will not readily reveal the defect. This paper describes a new method, based on the use of multiple frequency sweep, which addresses this concern. The Diagnostic Map that is proposed in this paper also enables rapid detection and unambiguous assessment of the soundness of adhesive and mechanically fastened joints. Thus, the user can conduct test with little training received.

A method was presented for extracting isotropic points in structures using simulated isoclinics obtained from a combination of photoelastic experiments and finite element analysis (FEA). This method was divided into two parts. The first part involved the confirmation of the boundary condition necessary for FEA using isochromatics obtained by photoelastic experiments. The second part involved the determination of isotopic points using simulated isoclinics obtained by FEA under the boundary condition confirmed by photoelastic experiments. This method was applied to a ring a T-shape plates subjected to a compressive load. The results showed that the isotropic points in the ring and T- shape plates could be accurately and easily extracted by the method.

Good measurements enjoy the advantage of conveying what actually occurs. However, recognizing that vast amounts of displacement, strain and/or stress-related information can now be recorded at high resolution, effective and reliable means of processing the data become important. It can therefore be advantageous to combine measured result with analytical and computations methods. This presentation will describe such synergism and applications to engineering problems. This includes static and transient analysis, notched and perforated composites, and fracture of composites and fiber-filled cement. Experimental methods of moire, thermo elasticity and strain gages are emphasized. Numerical techniques utilized include pseudo finite-element and boundary-element concepts.

Finite element (FE) analysis is a powerful technique for structural analysis. However, the analytical result by FE method are often not consistent with the experimental results due to uncertainties or assumptions in modeling structures, which can b lead to a lack of confidence in reliability of FE models. Therefore, it is extremely important to validate an FE Model so that the structure can obtain accurate prediction for linear response under unusual loads. This paper describes a methodology for validating FE models by integrating experimental and analytical data to correct uncertainties in modeling structures, through systematic comparison with dynamic response measurements. As an example an exercise on a full-scale reinforced concrete bridge was used to investigate the technique. AN FE model was set up and uncertain parameters such as Young's modulus and mass density of concrete and boundary conditions were updated to provide an accurate structural representation.

In order to solve fundamental process of the nucleation of the diamond, molecular dynamics simulation of the reflection of the carbon atom is conducted. Only one carbon atom is used for the simulation aiming to show fundamental process of the nucleation. The reflection phenomenon affected by the velocity and angle of incidence of the carbon atom is presented here. The position of carbon adsorption is discussed. Finally, it is shown that the reflection phenomenon is independent of the velocity and the angle of incidence.

In this paper, a measurement system for punching test of small holes in rigid copper clad laminates is presented. Copper clad laminate is a main raw material of consumer electronics, information and telecommunications devices. The process parameters such as blank temperature, blank thickness and material specifications strongly relate to the characteristics of the punching forces and displacements in copper clad laminates. The proposed system consists of small scale force transducer, displacement transducer and data acquisition system, with which the punching forces can be measured in each punch steps. A small punch with outer diameter 2 mm is directly connected to force transducer to measure the pushing and pulling forces during hole-punching process. Bushings and guide pins are used inside the die configuration in order to ensure the path straightness when punch moves into the die cavity. The experimental result show that the increase of punch and die clearances decreases the punching forces. The same consequence is obtained when increase of blank temperatures. In the final part of the proposed paper, a computer-aided analysis package ANSYS is used to verify the deformation and strain of the punch in the small hole-punching process. The punch's elastic deformation is small compared with blank thickness. The maximum equivalent Von-Mises stress in punch is smaller than its fracture stress. The research results are useful database when designing requirements of punch and ejecting force during at press factory.

This paper describes the results of a large-scale experimental test on T-tubular welded joint subjected under combined loading conditions. A special purpose rig is constructed for conducting the static and dynamic test of different tubular welded joints in the laboratory. The static test results are reported herein. Both the Strain gauge specimen testing which includes the basic brace axial, in-plane-bending, out-of-plane-bending and combined loadings cases, and also the finite element analyses had been carried out. The result obtained by the finite element analyses proved the accuracy and reliability of the numerical modeling. The study shows that the peak hot spot locations on the T-tubular joint subjected to combine loading shift from those of the basic load case. Generally, the peak hot spot stresses obtained by superposition are higher than that by direct analysis except for the areas that are near to the peak hot spot stresses location. The hot spot locations are important to decide on the placement of probes used in the fatigue test using the Alternating Current Potential Drop technique.

This paper presents three typical resistance strain gauge based force transducers developed with specific requirements of hydrodynamic model testing and have been very useful in test which otherwise would have been impossible or uneconomical. The transducers presented include those for measuring single and multi-component forces and moments.

Adhesively bonded composite patches employed for repairing fatigue cracks in metallic airframe structural components often fail under peel stress generated in the structure. The application of piezoelectric stress sensors embedded within the bonded joint for direct measurement of the peel stresses is reported here. Polyvinylidine fluoride (PVDF) film of about 28 micron thickness coated with nickel copper is employed to construct hin sensors embedded between the composite patch and the metallic surface of the crotch joint specimen. PVDF sensor with varying sizes were constructed and calibrated using polycarbonate test specimens subjected to uniaxial tension and compression. The sensors were then embedded between the composite patch and the metallic surface of the crotch specimen to monitor the peel stresses in the adhesive. The measurements are compare with stresses in the adhesive. The measurements are compared with stresses predicted by finite element modeling.

A novel speckle interferometry, called volume-grating speckle interferometry, is proposed in this paper. Large shearing out-of-plane displacement field can be measured by using this method. Theoretical analysis and experimental demonstration are given in this paper.

We investigated a method to evaluate fatigue damage of steels without contact using laser speckle. In the earlier stage of fatigue in steels, slipbands appear on the surface and microscopic phase strain is stored in the slipbands. The slipbands appear more densely with progress of fatigue damage. When a laser illuminates surface of the fatigued steel, light intensity distribution of the laser speckle pattern formed by the reflected light changes with the change of surface properties caused by slipbands. It has been clarified that width of the speckle pattern broadens corresponding to spatial frequency distribution of the surface profile and thus it is presumed that speckle pattern broadness with increase of slipband density. This shows that we can detect fatigue damage by observing the laser speckle pattern broadens with increase of slipband density. This shows that we can detect fatigue damage by observing the laser speckle pattern on material surface. The method presented in this paper is based on this phenomenon. We observed change of surface property and the speckle pattern during fatigue loading under constant stress amplitude using steel specimens. Surface roughness and fractal analysis of the surface profile diagrams were obtained to evaluate surface property. Change of surface roughness and fractal dimension of the surface profile were compared to change of laser speckle pattern depending on progress of fatigue damage and relation between surface property and speckle pattern was investigated. We investigated possibility of evaluation of fatigue damage observing laser speckle pattern during fatigue.

Digital speckle shearing interferometry is an optical method for measuring displacement derivatives directly and has gained wide acceptance for many industrial applications. Although it has a reputation for being insensitivity o vibration, an unfavorable environment may cause severe deterioration of the typical double-eye fringe pattern, making interpretation difficult. Digital image correlation has been found to be capable of detection displacement os points on images of illuminated object surface to a high degree of accuracy. This is achieved through a relatively simple set-up. This paper presents a method of compensating for any vibration of the object under study and thus alleviating the adverse effects of vibration on the quality of fringe patterns obtained by DSSI. This is achieved by incorporating DIC Into DSSI before the image subtraction phase of the technique. It is shown that good quality fringes can be obtained successfully for specimens vibrating at 25 Hz with amplitudes of up to 1mm.

A new polarized-type phase Doppler method is proposed for simultaneous measurements of particle size, velocity and refractive index on the basis of the phases of two polarized Doppler beat signals in a single scattering direction. Light scattered by a moving particle is divided into two rays, which are then detected with different polarization angles to transmit dominantly reflected or refracted rays. Signal phases of these two rays are measured with respect to the phase of beat signal obtained from the reference detector in the scattering plane. The particle diameter can be obtained from the phase of the reflected ray, whereas the particle refractive index can be determined from the phase ratio of the reflected and refracted rays. We carried out numerical simulations and experiments to confirm the usefulness of the prosed method.

The supply of fresh lubricant into a journal bearing plays an important role in determining the overall bearing performance. Lacking of supply generates excessive heat and may introduce starvation in the bearing which degrades the bearing overall performance or even cause an unscheduled overhauling. On the other hand excessive supply will be costly over longer term. Understanding the flow pattern of mixing process of the carried-over lubricant and the fresh lubricant supplied through bearing grooves is thus required.

An experimental study was conducted to investigate the velocity characteristics of inclined gravity plumes. Two slope angles, 20 and 40 degrees, were examined. The velocity measurements were performed with Digital Particle Image Velocimetry through a proper matching of the refractive index of the effluent and the ambient water. The simulations were conducted in an inverted manner to reduce the amount of ethanol required for the refractive index matching. Results show that the centerline U-velocity profiles in the free mixing region follows a similarity curve after approximately 30d. The normal spreading of the plume increase when the slope increases. On the other hand, a wider lateral spread occurs when the sloping angle decreases.

Fringe formations in holographic interferometry and speckle metrology are discussed in terms of correlation functions of randomly varying complex amplitude of light diffusely reflected from rough surface with the goal of surveying quantitative and automatic measurements by these methods. Dependencies of observed patterns on object deformation and optical systems are explained. Physical meanings of the derived relationships are explained in terms of dynamic behaviors of speckles resulting from surface deformation. Automatic measurements are described starting form analysis of fringe patterns resulting from photographic recording of specklgrams to digital recording of speckle patterns followed by direct digital correlation techniques and digital holography that uses both digital recording and reconstruction of holograms.

The recursive filtering algorithm, a simpler method of filtering for electronic speckle pattern interferometry (ESPI) images, is presented and studied in the paper. In pace with the new method, the applied software is developed specially. By experimental demonstration, it shows that the technique is the most effective and speedy method for the filtering of ESPI fringe patterns so far. Comparing with the images before and after filtering, we can see these advantages of the novel technique clearly.

A new method of quantitative phase evaluation of 2D fringe patterns based on Hilbert transformation is proposed. While it retains most of the advantages of the traditional Hilbert transformation method, the new method avoids the spurious discontinuities and sign reversals of the phase map from the classical Fourier-based methods. Only one interference pattern is required for the phase evaluation. The performance of the proposed method is evaluated by computer simulation.

In this paper the developed principle for Photomechanics is presented. This is composed of optical interferometry system with a modulator and digital image computer system. This illustrated method measures contour maps from fringe by fringe into point by point. The extracted phase information for Photomechanics can then be obtained by coding and decoding techniques in full field.

A non-contact optical approach to measure the in-plane displacement of an object is introduced in this paper. Through a ste of optical system, the image of the object to be measured is formed in the image plane of the CCD. When the object moves in-plane, its image moves in the image plane of the CCD accordingly. Consequently, the displacement of the object can be detected in real-time by measuring the movement of its image with CCD. The prosed w\system is suitable for non-contact measurement such as deformation of objects in high temperature, deformation of elastic objects and low frequency mechanical vibration. It can be widely used in mechanics experiments to achieve high precision measurement in long working distance.

In this paper, a strain measurement system for sheet metal forming by digital image processing technology and its fabrication process are presented. The principle strains as well as forming limit diagram can be obtained by using the proposed system. There are tow different approaches, namely the total least square optimization method and the multiple regression analysis method are studied. Comparing to the total least square optimization method, the multiple regression analysis method is simpler and faster within reasonable accuracy. The plastic strains of deformed parts are calculated based on the non-deformed reference configuration being a circle and the deformed configuration being a curve-fitting ellipse. The strain measurement of sheet metal forming is very important and useful. For example, it can be used to construct forming strain rate and temperature. The measurement result scan also be used to verify the numerical simulation results, such as finite element analysis. In the final of the paper, one industrial case study of fine stamping electronic part is discussed to demonstrate the prosed methodology.

The contact angle affects the life and accuracy of a linear guideway. A novel method for measurement the contact angel of linear guideway is proposed by using the photoelastic effect and digital image processing techniques. Tests of the method on a sliced linear guideway with various loadings demonstrate its usefulness. The stress distribution of the guideway is further studied by using the finite element method and the photoelastic experiment. The results can be useful for structural design of the linear guideway.

In this paper, a photoelastic stress analysis is carried out for a cracked femur bone with compression plate fixation. A loading rig has been designed and manufactured to apply forces in the physical directions on the 2D modal of the femur bone based on a single-leg-stance. Three femur models made of photoelastic materials had been fabricated with three configurations and loaded. A recently developed three- load to phase shifting method is adopted to extract the full-field quantitative information from the fringe patterns of the loaded models. A comparison shows that the configuration where the screws point away from each other had the best effectiveness.

The shattering of glass glazing in modern buildings during occurrence of fire poses an important life safety problem. A shattered glass glazing produces a vent that allows the rapid spread of toxic fire gases to remote areas and also serves to promote fire growth through an influx of fresh air. Recent efforts to gain better understand of this problem are primarily done through experimental investigations of temperature distribution, thermal stresses and breaking time using medium and full-scale fire test. However, the cost and time of conducting such test are high and information obtained is often limited and shows fairly large scatter. In this study, a bench scale experimental set-up was developed to investigate the thermal stresses in radiatively-heated glass samples of up to 100 by 100 mm in size and mounted freely in a frame on all edges like a glass glazing. It provides a cheaper and more effective means to understand the development of thermal stresses prior to fracture in developing the theory of glass breakage in fire. A truncated cone heater was designed and fabricated to provide a radiant flux of between 10 and 50 kW/m² on the glass samples. The truncation allowed the optical path of the polariscope to pass though the glass samples to reveal the developing fringe patterns during the heating process. Result of iso chromatics and iso clinics were obtained to interpret the stress patterns in the glass samples and relate them to the potential sites for fracture initiation. With slight modifications of the experimental set up, the cracking of glass samples was also captured to reveal the fracture process.

This study presents the different possibilities of measuring mechanical quantities on biological materials by means of optical methods. These methods allow to perform non-contact and non-disturbing evaluations. The goal is to determine the mechanical characteristics of human organs to be able to model them in order to carry out digital simulations closer to reality. We will set out a method which measures the relief, another one which measures a field of displacements and the last one strain tensors.

Human bodies are often exposed to vertical vibrations when they are in the workplace or on vehicles. Prolonged exposure may cause undue stress and discomfort in the human body especially at its resonant frequency. By testing the response of the human body on a vibrating platform, many researchers found the human whole-body fundamental resonant frequency to be around 5 Hz. However, in recent years, an indirect method has been prosed which appears to increase the resonant frequency to approximately 10 Hz. To explain this discrepancy, experimental work was carried out in NTU. The study shows that the discrepancy lies in the vibration magnitude used in the tests. A definition of human natural frequency in terms of vibration magnitude is proposed.

This paper presents experimental studies on diffuse reflectance spectra of blood in cylindrical glass vessels embedded in the Intralipid solution as a skin tissue model, and also f human skin surfaces. The measured spectra are mainly governed by the absorption characteristics of a small amount of blood added into the Intralipid medium. To evaluate quantitatively diffuse reflectance spectra, we employed the color perception on the basis of the CIE x-y chromaticity diagram. Results for the skin tissue model were found to coincide with those for veins in the human skin tissue.

In this paper are shown the analytical study as well as experimental result carried out on non-human bones. The analytical studies were focused on the observation of the bone behavior under impact loads, longitudinal as well as traversal. Previous to the present work modal analysis study was carried out on the model in order to determine its natural frequencies trough, which the Rayleigh coefficients (alpha) and (beta) associates to the damping of the dynamic systems, were determined. The solution was found using finite element method by means of the ANSYS program. The experimental studies consisted of the slow and monotonous application of compression loads on the specimens recording the level of displacement and deformations. Simultaneously a laser beam was applied to the bone surface, recording the speckle pattern on each load cycle. The obtained results are shown graphically plotting the Von Misses stresses and displacement for the analytical case, and (sigma) -(epsilon) , and Ds-P relations for the experimental case.

When subjected to vertical vibration, a human behaves as a mass-spring-damper system rather than solely as a mass on the structure. The interaction between the human body and the structure results in a significant increase in the damping of the human-structure system. In published research, the human body has been modeled as a multi-degree of freedom system. Various experimental methods have been used to identify the relevant human model dynamic parameters such a the stiffness and damping. However there is lack of information on quantifying the damping effects of human- structure system. The study reported here prosed application of energy dissipation to evaluate the damping effects. During vibration, the human absorbs energy and also includes damping in the structure. It has been found that human postures like sitting, standing affect energy dissipation. Results from laboratory studies using a human on a vibrating concrete slab instrumented to record force and velocity at the vibration power source and the human/structure interface are presented.

A software is developed which enables reconstruction of the 3D shape of fracture surfaces without human assistance. It is based upon computer image processing and pattern recognition techniques by using a stereo-pair of scanning electron micrographs. The processing consists of two subprocesses: searching the matching points between two images and computation of heights using het relative shift of the matching points. By using the previously developed system, some mismatches were inevitable in the search process, in particular, for low-contrast SEM images such as striations, intergranular facets, and so on.

A Wollston prism with polarizing elements is used in optical interferometry. Double light source images can be to shear by the prism and to control exposes. According to shear theory, the optical effect caused by the deflection in this arrangement is formed frequency grating and/or carrier fringe pattern. The projects of classical, holographic, speckle interferometry, etc. can be to investigate with this modulator.

A technique is introduced for the shape inspection of workpieces in production lines. This procedure is based ona new active technology in optical shape measurements the so- called inverse projected-fringe-technique. Based on an existing master object or its reconstructed shape an adapted fringe pattern can be computed and projected using a free- programmable LCD-matrix. Such an inverse projection can be used for the comparison between a sample and its master piece in quality control. Having a test object that completely fits in shape with the master piece the inverse projection delivers an equidistant and non-distorted fringe pattern under the same observation direction. However, every faulty object area of the sample causes distortions relatively to this known model and can be consequently detected very fast by means of suitable correlation techniques. Especially the simplicity of the master pattern offers the possibility of very simple filters and evaluation procedures such as the spatial heterodyne-technique.

This paper describes the use of optical fringe projection method for 3D surface profile measurement of object. In this method, sinusoidal linear fringes are projected on the object surface by a programmable liquid crystal display projector. The image of the fringe patter in captured by a CCD camera and processed by phase-shifting techniques. A simple procedure is described which enables calibration of the optical set-up for subsequent quantitative measurement of unknown object shapes. This method is relatively simple and accurate, and is capable of conducting fully automated measurements.

A simple yet effective schlieren technique to observe and obtain quantitative information of surface flatness is described. Basically, in schlieren method the object to be tested is imaged using a parallel beam illumination. At the focal point of a positive imaging lens or mirror, a stop is inserted to pass only those rays that correspond to some deviation in the object. In this way the deviation can be displayed as a light and dark pattern on the observation plane. However, quantitative interpretation is difficult since the single display is fixed by the stop dimension.

The paper describes a series of analytical and physical model studies conducted to develop an online monitoring system for offshore platforms. An actual offshore jacket platform situated in a water depth of 88m was selected for the study. A detailed 3D finite element analysis of the platform involving free and forced vibration revealed that there were dynamic characteristics of the platform which could be used to identify the structural damages in the structure. Having established the feasibility of the method, further work was carried out on a physical model of the platform. Dynamic characteristics of the model were determined by spectral analysis of the response data, simulating various changes including compete and partial damages on individuals elements of the model. Simultaneously work was also initiated to apply the result of the physical model tests for interpreting the causes of the changes in the dynamic characteristics using ANN trained with the database created through experiments and analysis. The final outcome of these comprehensive studies was a scheme for integrity monitoring of jacket type of fixed offshore platforms using vibration characteristics of the structure.

The Singapore-Malaysia Second Link is a prestressed bod girder carrying a dual carriageway with three lanes on each carriage. The bridge serves as a relief to the existing crossing locate in northern Singapore. The bridge was compete in 1997 and opened to traffic in the same year. Owing to its importance a suite of instruments was installed in three segments of the bridge in order to monitor its short-term and long-term behavior and performance under construction loads, environmental loads, and vehicular loads. The paper present a description of the instrumentation, results of the monitoring during construction, and observations of the bridge response to loading during construction.

The fundamental characteristics of AE signals, such as the attenuation, frequency dependency of AE signals, were investigated and the fracture process of the single fiber composite (SFC) was examined. As a result, the frequencies of AE signals were almost unchanged, while the amplitudes attenuated greatly with the increment of the propagation length. This proved that the frequency analysis is an effective way in processing AE signals of composite materials. In the fracture process of the SFC the number of AE events was in a good agreement with the number of fiber breakages, and the sources of AE signals were the failure modes at fiber breakages. Using the prosed time-frequency method of wavelet transform to process AE signals, the micro failure modes at a fiber breakage and the micro fracture mechanism, such as the sequence of each failure mode and their interaction, were made clearer. These gave that the both processing methods of AE signals, FFT and WT, were powerful for identifying the micro failure modes and for elucidating the micro fracture mechanisms in composite materials.

Fiber Bragg grating (FBG)-based strain and temperature sensor array were embedded into the concrete structure in order to provide real-time information on its strain and temperature distribution. The sensors were wavelength- multiplexed along a single fiber. The temperature and strain sensors were specially designed and optimized for their measurands. The calibration experiments of those FBG sensors, and parameter monitoring during the structural curing processes were also presented in this paper. These fiber optic strain and temperature sensor show many advantages over the traditional electrical strain gauges and thermocouples.

Bridge health monitoring is defined as the continuous monitoring of a bridge's state properties such as static and dynamic response in order to diagnose the onset of anomalous structural behavior. This involves measuring and evaluating the state properties and relating these to defined performance parameters. The process of measuring state properties, either continuously or periodically, produces large amounts of data. Careful analysis of dat would detect any sudden and gradual changes in the bridge, and thus enable damage detection, location, and severity. There is therefore a need for data analysis tools that enable bridge managers to identify as much information as possible on bridge behavior and performance at given tie. The ability of wavelet transforms to detect abrupt changes; gradual change beginnings and ends of events make them well suited for the analysis of bridge health monitoring data. This paper presents the application of wavelet analysis to identify events and changes in a bridge during its construction.

This paper presents hybrid holography-tomographic technique whereby surface displacement around an area inaccessible by direct optical exposure is measured holographically and the displacement in the obstructed area is calculated by a tomographic technique.

Laser based interferometric techniques find many applications in spacecraft component testing. Holographic Interferometry and electronic speckle interferometry are two such laser based interferometric techniques that are used at our Laboratory for non-destructive evaluation of spacecraft components like honeycomb sandwich panels and propellant tanks. An overview of these techniques, optical setups and applications for various spacecraft components are presented.

An optical system for lensless Fourier transformed holographic interferometry is constructed to enable the measurement of minute displacement from nm to micrometers scale and corresponding strain distribution using a CCD camera. In this technique, Fourier spectrum of the object beam is recorded on a hologram then the hologram image is easily reconstructed by a single pass of 2D FFT. In this paper, phase difference distribution is wrapped from -(pi) to (pi) , unwrapping process is required. The maximum spanning tree method is adopted here, which seeks a spanning tree that maximizes overall edge weights given by the cross amplitude. Displacement is calculated from the phase difference distribution. Even if there is no problem in the precision of loading device, displacement distribution of the object can be measured easily with high precision.

The carrier fringe is frequently used together with conventional double-exposure holography and shearography. The pattern of the carrier fringes to be used is affected by the pattern of the deformation fringes, for instance, parallel fringe-lines will not be useful for beam bending problems and concentric circular carrier fringes will be unsuitable for circular plates under axisymmetrical loading. The formation of holographic fringe patterns has been explained using the moire fringes that are generated by optically differentiating the ellipsoids of holodiagrams. This paper describes a new method based on the hyperboloids instead of ellipsoids. With this method, the hyperboloids directly depict holographic carrier fringe patterns; to understand the formation of shearographic patterns, only one optical differentiation is made on the hyperboloids. This therefore will allow easy understanding of how the light source should be shifted in generating the appropriate carrier fringe patterns.

There are some important problems for quantitative measurement of the structure vibration by interferometric optical fiber sensor which is embedded in civil engineering and composite material structure are described in this paper.

IN this paper we propose a simple optical fiber sensor for the measurement of vibration. The sensor consists of two fiber Bragg gratings, which have partially overlapped reflection spectra and are mounted on the opposite sides of a flexible beam. With this setting, the light intensity reflected by the gratings is modulated by the vibration of the beam and adverse thermal effects can be largely eliminated. Experimental results are presented to demonstrate the feasibility of the sensor.

The effect of unwanted interferometric signals on the wavelength detection accuracy in a fiber Bragg grating sensor array using a tunable laser and a first derivative interrogating technique are investigated. The strain resolution of 1.2 (mu) (epsilon) has been achieved by proper modulating the laser wavelength.

A novel technique is applied to study dispersion in GRIN optical fiber using a laser sheet of light. The dependance of the dispersion on the incident angle and on other parameters is also studied. The interference pattern between different rays is observed experimentally and investigated theoretical. Two systems of interference pattern are produced. The first pattern consists of the interference between the rays passing through the cladding and the reference beam passing through the cladding and the core of the optical fiber and the rays passing through the surrounding medium.

This paper present an analysis technique that uses vibration response data from a continuously Scanning Laser Doppler Vibrometer (SLDV) to determine both the mode shape modulus and the temporal phase relationships by means of the Time Domain Fourier Filter Output method. Verification of this technique is first performed using numerically generated data from the exact solution of a cantilever beam, to simulate experimental measurements with the SLDV. Finally, an experiment is presented to show that this technique works well for determining both the modulus and the temporal phase of mode shapes using only the velocity output form an SLDV without any reference force signal.

The packaging of IC packages has changed over the years, form dual-in-line, wire-bond, and pin-through-hole in printed wiring board technologies in the 1970s to ball grid array, chip scale and surface mount technologies in the 1990s. Reliability has been a big problem for manufacturers for some moisture-sensitive packages. One of the potential problems in plastic IC packages is moisture-induced popcorn effect which can arise during the reflow process. Shearography is a non-destructive inspection technique that may be used to detect the delamination and warpage of IC packages. It is non-contacting and permits a full-field observation of surface displacement derivatives. Another advantage of this technique is that it is able to give the real-time formation of the fringes which indicate flaws in the IC package under real-time simulation condition of Surface Mount Technology (SMT) IR reflow profile. It is extremely fast and convenient to study the true behavior of the packaging deformation during the SMT process. It can be concluded that shearography has the potential for the real- time detection, in situ and non-destructive inspection of IC packages during the surface mount process.

The purpose of this paper is to show the developed laser interferometry for measurements of the small dynamic displacements. The optoelectronic method of the signal registration from laser interferometer and the method of the signal processing are presented. This technique allows us to determine the among and from of the dynamic displacements with high sensitivity and accuracy.