In the compact digital holoscope (CDH) measurement process, theoretically, we need to ensure the distances between the reference wave and object wave to the hologram plane exactly match. However, it is not easy to realize in practice due to the human factors. This can lead to a phase error in the reconstruction result. In this paper, the strict theoretical analysis of the wavefront interference is performed to demonstrate the mathematical model of the phase error and then a phase errors elimination method is proposed based on the advanced mathematical model, which has a more explicit physical meaning. Experiments are carried out to verify the performance of the presented method and the results indicate that it is effective and allows the operator can make operation more flexible.

Optical interferometry is a popular technique for high precision measurement. It produces fringe patterns for analysis. The output fringe patterns usually have noises, and thus a filtering process for fringe patterns is necessary. A few filtering algorithms, such as windowed Fourier filtering (WFF), have been proposed specially for fringe pattern denoising. Meanwhile, filtering techniques have been intensively studied for a long time in the general image processing area. It is curious that how the filtering techniques in general image processing area perform on fringe pattern denoising. In this paper, a state-of-the-art filtering algorithm, block-matching 3D filtering (BM3D), is selected and compared with the WFF.

In this paper a one-shot method to determine the shape of an object from overlapping cosine fringes projected from multiple projectors is presented. This overcomes the limitation with single projector systems that do not allow imaging the entire object with a single shot. This research projects orthogonal grey scale sinusoidal fringes simultaneously onto an object and separates them using resonance decomposition. Resonance decomposition is a method that separates signals based on the idea of resonance, whether or not a signal exhibits a high degree of sustained oscillation, and can separate high and low resonance components of a signal even if they overlap in the frequency domain. In addition to pattern separation a novel method of phase error compensation is proposed using the mean value for each period ranging from [–π,π] as the basis for a look up table (LUT). It is shown that this method of error compensation is able to reduce the error caused by non-sinusoidal waveforms to a level comparable to the single view 3-phase shift profilometry method.

High temperature deformation and strain are important measures for characterizing behaviors of structural components under high temperature conditions. Digital Image Correlation (DIC) is a full-field technique based on white-light illumination for displacement and strain measurement. But Light spectrum on the sample surface at high temperature affect the quality of acquired speckle pattern images for traditional DIC measurement. This paper proposes an innovative UV-DIC system which in conjunction with ultraviolet illumination and a filtering system to minimize the surface radiation effect and enable deformation and strain measurements at high temperatures. The test sample with a specially-selected coating material was heated by means of high temperature furnace, which process to form stable speckle pattern on the sample surface. The surface was illuminate by UV light and simultaneously an UV sensitive CCD camera was used to record digital speckle image of test sample surface under different temperatures. Using DIC method for image analysis and processing obtains full-field thermal deformation, which implements a set of image average algorithms for eliminates interference of vibration and noise. The experimental results show that the UV-DIC can achieve high temperature measurement, and effectively remove the interference of vibration and noise in high temperature measurement.

This paper explains the procedure for analysing surface strains and the detection of near-surface defects by means of a novel measurement device. The measurement instrument combines the shearographic measurement principle with an endoscope. In the field of non-destructive testing, the optical measurement technique provides a possibility for the detection of near-surface defects. As a full-field, noncontact, coherent-optical and non-destructive testing and measuring method on surfaces, electronic shearography meets those requirements. Irregularities on body surfaces can be recorded up to a dimension that is within the range of the used laser light wave-length. With shearography, objects as well as whole structures can be checked independently of their material. Shearography measures the strains as well as the gradients of the deformation in the given direction of image-shearing. From the quantitative strain measurement, stresses in the specimen surface can be observed. By a qualitative evaluation of the shearogram, strain concentration and thus imperfections are located. Through the endoscope, the measurement method of shearography is expanded equipment-wise. In this way, shearography enables examinations of cavities in technical units through the smallest holes. The shearographic-imaging endoscope is the Interferoscope. The Interferoscope is used, where conventional shearography fails as the examined location is difficult to access. With the Interferoscope, examinations of objects are just as well possible under application of dynamic excitation. This brings up the advantage, that also deep-seated imperfections are noticeable on the surface and are thus detectable. Through the dynamic measurement excitation the detection of object specific eigenfrequencies becomes as well possible.

We have been proposed a phase shifting speckle shearing interferometer using a diffraction grating for measuring the strain distribution. A strain is obtained by the spatial differentiation of the in-plane component of the deformation. In this system, to measure the in-plane component of the object deformation, the object surface is illuminated in two symmetrical directions about the normal of the object surface. Moreover, the spatial differentiation of the in-plane deformation and phase-shifting are achieved by the diffraction grating. However, the object surface is illuminated by a He-Ne laser in the conventional method, and the illuminating direction is changed by switching the optical path mechanically. Then, we use laser diodes as a light source which has high power and is small size. But, coherency of laser diode is low. In this method, as common path arrangements are used, the path difference is so small that sheared speckles interfere each other. Therefore, the laser diode can be applicable for this measuring system. Additionally, in order to illuminate the object from two directions, two independent laser diodes are used. So, the optical path change is performed electrically. The strain distribution of the bending cantilever is measured with this two laser diodes method. The measured result coincides with theoretical value qualitatively. Therefore the experimental results show the validity of this method.

In the last decade, due to the fast development of phase-shift technique, the measurement sensitivity of digital shearography (DS) technology has been increased tens of times which brings the technology itself a wide acceptance by the industry as a practical measurement tool for quality inspection and non-destructive testing. In common sense, compare to Temporal Phase-Shift Digital Shearography (TPS-DS), Spatial Phase-Shift Digital Shearograhy (SPS-DS) has the advantage of a broader capability for both static and dynamic measurement applications while keeps the disadvantage of lower phase-map quality. Recently, with new developments, the phase map quality of spatial phase-shift digital shearography has been greatly improved which is now comparable to the temporal phase-shift technique. This article gives a review of recent developments of spatial phase-shift digital shearography. Theory, experimental setup, phase-map results and applications are shown in detail.

A compact reflection digital holographic microscopy (DHM) system integrated with the light source and optical interferometer is developed for 3D topographic characterization and real-time dynamic inspection for Microelectromechanical systems (MEMS). Capability enhancement methods in lateral resolution, axial resolving range and large field of view for the compact DHM system are presented. To enhance the lateral resolution, the numerical aperture of a reflection DHM system is analyzed and optimum designed. To enhance the axial resolving range, dual wavelengths are used to extend the measuring range. To enable the large field of view, stitching of the measurement results is developed in the user-friendly software. Results from surfaces structures on silicon wafer, micro-optics on fused silica and dynamic inspection of MEMS structures demonstrate applications of this compact reflection digital holographic microscope for technical inspection in material science.

Thermoelastic stress analysis (TSA) is an established active thermographic approach which uses the thermoelastic effect to correlate the temperature change that occurs as a material is subjected to elastic cyclic loading to the sum of the principal stresses on the surface of the component. Digital image correlation (DIC) tracks features on the surface of a material to establish a displacement field of a component subjected to load, which can then be used to calculate the strain field. The application of both DIC and TSA on a composite plate representative of aircraft secondary structure subject to resonant frequency loading using a portable loading device, i.e. ‘remote loading’ is described. Laboratory based loading for TSA and DIC is typically imparted using a test machine, however in the current work a vibration loading system is used which is able to excite the component of interest at resonant frequency which enables TSA and DIC to be carried out. The accuracy of the measurements made under remote loading of both of the optical techniques applied is discussed. The data are compared to extract complimentary information from the two techniques. This work forms a step towards a combined strain based non-destructive evaluation procedure able to identify and quantify the effect of defects more fully, particularly when examining component performance in service applications.

Nondestructive inspection of a high-temperature structure is required to guarantee its safety. However, there are no useful sensors for high-temperature structures. Some of them cannot work at temperatures over 50°C.Another concern is that it is too expensive to use. Therefore, a sensing system, which can transmit and receive an ultrasonic wave and travel a long distance using a long waveguide, has been studied. This means that an ultrasonic sensor could be driven at atmospheric temperature. We could finally confirm that a guided ultrasonic wave generated by a trial electromagnetic acoustic transducer (EMAT) with a thin Ni sheet on the surface of the pipe can travel more than 10m using a thin bar with a 2mm diameter as the waveguide. However, we had difficulty in receiving a reflected ultrasonic wave from the bottom surface of a test specimen. We tried to improve the trial inspection system using an ultrasonic horn. Finally, an experiment in which the temperature of a test block was heated to about 500°C has been done and the reflected ultrasonic wave from the bottom surface of it has been successfully detected using a long waveguide and the wave horn. Finally, we tried to transmit and receive a guided wave in a pipe using the developed system. It was determined that an additional one turn-shaped or wave-shaped waveguide attached to the surface of the pipe in the circumferential direction is useful.

A set of electrolyte capacitors were inspected using x-ray micro-computed tomography (μ-CT) system developed at the Department of Physics Gadjah Mada University, Indonesia. Testing was done for three electrolyte capacitors. The one is in good condition and the other two are considered broken. Those were broken due to either high voltage operation or leakage of the tube. Under customized μ-CT inspection, 3-D presentations of the objects have been developed. The results showed that the image profiles, radiation attenuation profiles and linear attenuation coefficient distribution on top, middle and bottom area were able to determine the aluminum plate and electrolyte papers. Good electrolyte capacitor has higher radiation attenuation and nearly uniform across the core of the capacitor. This is in contrast with the broken capacitors.

A method for sinogram data interpolation based on a sinusoidal pattern in computed tomography has been developed. Sampled sinograms were acquired based on angular interval scanning of 5^o, 10^o, and 20^o. Then each resulted sinogram was interpolated following sinusoidal pattern to make a complete full scanning sinogram as if they were sampled at 1^o. After that, a formal summation convolved filtered back projection was applied to each sinogram to yield a crosssectional image. This method was successfully interpolated limited number of projections data to obtained complete sinogram. It works for simple and homogenous object. However, for high variation of physical properties, e.g. linear attenuation coefficient values, this method needs more consideration on interpolation strategies to produce good image.

Ghost imaging with single-pixel bucket detector has attracted more and more current attention due to its marked physical characteristics. However, in ghost imaging, a large number of reference intensity patterns are usually required for object reconstruction, hence many applications based on ghost imaging (such as tomography and optical security) may be tedious since heavy storage or transmission is requested. In this paper, we report that the compressed reference intensity patterns can be used for object recovery in computational ghost imaging (with single-pixel bucket detector), and object verification can be further conducted. Only a small portion (such as 2.0% pixels) of each reference intensity pattern is used for object reconstruction, and the recovered object is verified by using nonlinear correlation algorithm. Since statistical characteristic and speckle averaging property are inherent in ghost imaging, sidelobes or multiple peaks can be effectively suppressed or eliminated in the nonlinear correlation outputs when random pixel positions are selected from each reference intensity pattern. Since pixel positions can be randomly selected from each 2D reference intensity pattern (such as total measurements of 20000), a large key space and high flexibility can be generated when the proposed method is applied for authenticationbased cryptography. When compressive sensing is used to recover the object with a small number of measurements, the proposed strategy could still be feasible through further compressing the recorded data (i.e., reference intensity patterns) followed by object verification. It is expected that the proposed method not only compresses the recorded data and facilitates the storage or transmission, but also can build up novel capability (i.e., classical or quantum information verification) for ghost imaging.

Phase retrieval techniques like phase-shifting method and Fourier-transform technique provides accurate phase distribution for static measurements. However, it is extremely difficult to use these techniques for dynamic measurement. In this paper, an automated fringe analysis technique to retrieve phase distribution from single fringe pattern is proposed. The proposed method uses Teager-Hilbert-Huang transform, which is based on empirical mode decomposition (EMD), vortex operator (VO) and Teager energy operator (TEO) for fringe demodulation. The proposed method is suitable for both static and dynamic measurements. In this method, a fringe pattern is normalized using EMD and VO generates a complex field of the signal. Finally TEO is used to obtain the phase and its phase derivatives map. Unlike traditional phase retrieval algorithms, this method provides unwrapped phase derivatives directly. Hence there is no need for a separate phase unwrapping process. The proposed method is validated using simulated fringe patterns and experimental data obtained from electronic speckle pattern interferometry (ESPI). The results show that this method determines the phase map and its derivatives from the single fringe pattern effectively.

A new nonlinear optical image encryption scheme based on a modified amplitude phase retrieval algorithm is proposed. With two random phase masks that serve as the public encryption keys, one iterative amplitude and phase retrieval process is employed to encode the primary image into a stationary white noise. The two private keys generated in the encryption process are randomly distributed binary matrices to be used to perform one-way binary phase modulations. The proposed encryption process is nonlinear and offers enhanced security. Numerical simulations are presented to demonstrate the feasibility and security of the proposed system. The results also illustrate that the computing efficiency of the algorithm is improved and the number of iterations is much less than that of cryptosystem based on Yang-Gu algorithm, which has two iteration processes.

The purpose of this study is to evaluate the crack-healing behavior of SiN_x/SiC nanolaminated films quantitatively. SiN_x/SiC nanolaminated films were fabricated by alternating ion-beam assisted deposition of SiN_x and SiC. The fabricated nanolaminated films consisted of four layers with the top layer being SiN_x. Smooth and notched microbeam specimens were fabricated using a focused ion beam (FIB) system. The nanosized notch was introduced in form of an imitational crack on the film surface by FIB. Some notched samples were heated at 1000 ºC for 24 to 96 h in air. The fracture strength was evaluated by bending tests using a nanoindentation system. After heating, the notch was filled with reaction products. Energy dispersive X-ray (EDX) analysis revealed that the reaction products contained oxide compounds, most likely SiO₂. The fracture load of the notched specimens recovered with increasing heating time. The filling of the notch with oxidation products caused the recovery of the fracture load. However, the recovery was not complete compared with the strength of a smooth sample. It is concluded that the filling of a notch with oxidation products recovers the mechanical strength of SiN_x/SiC nanolaminated films only to a certain extent.

A new method for measuring in-plane vibration velocity of glossy and specular surface using differential laser Doppler vibrometer (LDV) is proposed in this work. A standard tangential LDV using similar differential configuration is only able to measure in-plane velocity of objects with rough surface, due to its inherent on-axis optical design that collects backscatter light along its optical axis. The proposed method adopts an off-axis detection scheme, in which the photodetector is decoupled from LDV, and placed along the dominant direction of the scattered light. For optimal placement, the bidirectional reflectance distribution function (BRDF) of the sample must be considered ideally, but in our measurement tests, the off-axis detection along the direction of specular reflection is sufficient to obtain good measurement results. Another advantage with this setup is that it also works with the objects with rough surface. Experimental works using the standard tangential LDV and a prototype of this method were conducted to measure the in-plane motion of four different samples representing rough, glossy and mirror-like surface. An electrodynamic shaker was used to provide the in-plane motion of the samples at three different frequencies. A single point axial vibrometer was used to validate the in-plane velocity of the measurement from both in-plane LDVs. Some preliminary results showed that the in-plane motion of the object with glossy and specular surface can be measured using the proposed method.

Essentially, 3D computed tomography (CT) image should be obtained from huge data (raysum) set from multiple views and multiple projections. Due to mechanical limitation, a compromise between fast scanning process and quick data sampling has to be considered. This paper presents our approach on performing the fast scanning process and quick data sampling in order to obtained good CT image with acceptable criteria. A set of nice results were presented.

In principle, PMD needs the two components of the local surface gradient. Therefore a sequence of two orthogonal sinusoidal fringe patterns have to be displayed and captured separately. It is easy and convenient by using a digital display, but it will be much difficult to build a PMD system with mechanic gratings. In this paper, we present a novel phase-shift technique by using the cross fringe pattern, in which a one-dimensional N-phase shift allows for the acquisition of the two orthogonal phases, with only N exposures instead of 2N exposures. Therefore, it make PMD possible be implemented by a one-dimensional translation of the fringe pattern, instead of the common two-dimensional translation, which will be quite useful for certain applications.

A model for 3D image reconstruction of x-ray micro-computed tomography scanner (micro-CTScan) has been developed. A small object has been put under inspection on an x-ray micro-CTScan. The object cross-section was assumed on the x-y plane, while its height was along the z-axis. Using a radiography plane detector, a set of digital radiographs represents multiple angle of views from 0º to 360º with an interval of 1º was obtained. Then, a set of crosssectional tomography, slice by slice was reconstructed. At the end, all image slices were stacked together sequentially to obtain a 3D image model of the object being inspected. From this development, lessons on the way to have better understanding on the internal structure of the object can be approached based on the cross-sectional image slice by slice and surface skin.

Crystal structure of titanium alloy changes from alpha (hexagonal close-packed) to beta (body centered cubic) with increase of beta stabilizer content. This change of structure strongly influences on the plastic deformation behavior of titanium alloys, because it not only induces changes of slip systems but also activates martensitic transformation and deformation twinning. However, most of past studies on titanium alloys have been focused on the development of specific functionalities induced by alloy designing, and few research works have been reported on metal workability under multi-axial stress conditions, which is key factor to apply titanium alloys for engineering products. In this study, uniaxial and biaxial compression tests of titanium-niobium alloys with various niobium contents have been performed to clarify the influence of beta stabilizer content on the plastic behavior under compressive stress conditions. The titanium-niobium alloys were solution treated and then quenched from beta region to obtain metastable structures. The resultant stress-strain relations together with microscopic observations of texture revealed that the influence of niobium contents on the predominant plastic deformation mechanisms and thus on the hardening phenomena. The equi-plastic work contours obtained by uniaxial and biaxial compression tests also implied the crystal structure dependency of anisotropic hardening, which was evaluated quantitatively by means of Hill's anisotropic yield criterion. The results will provide information on the versatile constitutive relations of titanium alloys containing beta stabilizer elements, that is important to prove the performance of products manufactured by compressive metal working processes such as forging and extrusion.

In this study, a method for identifying the elastic material characteristics of a heterogeneous material from measured displacements is proposed. The virtual fields method is employed for determining the elastic material characteristics. The solid propellant is considered as heterogeneous materials for the test subject. An equation representing the distribution of the material properties of the solid propellant is obtained by Fick’s law, and the distribution is applied to the virtual fields method. The effectiveness of the proposed method is demonstrated by applying to displacement fields obtained using finite element analysis. Results show that the heterogeneous material properties can be obtained by the proposed method.

Layered structures, used in many applications such as windshields, thermal protection systems, heavy armor etc., are comprised of layers having different elastic and fracture properties. Present study focuses on understanding the behavior of cracks in a layered plate oriented in such a way that there are property jumps across the crack front. Two layer plates were fabricated by joining Polymethylmethacrylate (PMMA) and epoxy sheets using an epoxy based adhesive (Araldite). Single edge notched specimens were subjected to mixed mode loading using the asymmetric four point bending configuration. The results of the study indicated that the failure in two layer plates is progressive in nature. Crack extension starts in the most vulnerable layer (epoxy) first and the crack grows in a sequence of jumps and arrests in this layer. Once this crack reaches a particular length the crack in the second layer starts extending resulting in final failure of the plate. Similar sequence of events was observed in the case of dynamically loaded samples. The predictions of the load at which epoxy crack starts growing and the angle at which the crack grows using the maximum tensile stress criteria were in reasonable agreement with the experimentally observed values.

In this study, the effect of the plastic deformation on the microscopic structure and the anisotropy of the elastic modulus in the cold-rolled steel sheet (SPCC) is investigated. Various uniaxial plastic strains (0%, 2.5%, 5%, 7.5%, and 10%) are applied to the annealed SPCC plates, then, the specimens for the tensile tests are cut out from them. The elastic moduli in the longitudinal direction and the transverse direction to the direction that are pre-strained are measured by the tensile tests. Cyclic tests are performed to investigate the effects of the internal friction caused by the movable dislocations in the elastic deformation. Also, the movable dislocations are quantified by the boundary tracking for TEM micrographs. In addition, the behaviors of the change of the elastic modulus in the solutionized and thermal aged aluminum alloy (A5052) are measured to investigate the effect on the movable dislocations with the amount of the depositions. As a result in SPCC, the elastic moduli of the 0° and 90° directions decrease more than 10% as 10% prestrain applied. On the other hand, the elastic modulus shows the recovery behavior after the strain aging and the annealing. The movable dislocation and the internal friction show a tendency to increase as the plastic strain increases. The marked anisotropy is not observed in the elastic modulus and the internal friction. The elastic modulus in A5052 with many and few depositions decreases similarly by the plastic deformation. From the above, the movable dislocations affect the elastic modulus strongly without depending on the deposition amount. Moreover, the elastic modulus recovers after the plastic deformation by reducing the effects of them with the strain aging and the heat treatment.

Electric double layer capacitors (EDLC) cells have a process variation and temperature dependency in capacitance so that balancing is required when they are connected in series, which includes electronic voltage management based on capacitance monitoring. This paper measured temperature aspect of capacitance periodically to monitor health and degradation behavior of EDLC stressed under high temperatures and zero below temperatures respectively, which enables estimation of the state of health (SOH) regardless of temperature. At high temperature, capacitance saturation and delayed expression of degradation was observed. After cyclic stress at zero below temperature, less effective degradation and time recovery phenomenon were occurred.

The fracture behavior of notched polycarbonate (PC) is investigated as a function of loading rate ranging from quasistatic to dynamic. Complementary numerical simulations are performed using the experimentally obtained load-point displacement as the input. The results indicated that in the rage of loading rates considered, the fracture initiation toughness of PC is not sensitive to loading rate. The fracture processes near the dynamically loaded notch-tip was observed using ultra-high speed imaging. In both quasi-static and dynamic loading, defects nucleate ahead of the notch tip and coalesce before final fracture. In quasi-static tests there is considerable time lag between defect nucleation and final fracture, whereas in dynamic experiments the two are almost synchronous.

In the present work, the behavior of thin adhesively layer in patch repaired carbon fiber reinforced polymer (CFRP) panel under tensile load is investigated experimentally using digital image correlation (DIC) technique. The panel is made of Carbon/epoxy composite laminate and the stacking sequence in the panel is [0º]₄. A circular hole of 10 mm diameter (d) is drilled at the center of the panel to mimic the case of low velocity impact damage removal. The panel with open hole is repaired with double sided (symmetrical) and single sided (unsymmetrical) rectangular patch made of same panel material having stacking sequence of [0º]₃. Araldite 2011 is used for bonding the patch onto the panel over the damaged area. The global behavior of thin adhesive layer is examined by analyzing whole field strain distribution using DIC. Longitudinal, peel and shear strain field in both double and single sided repair configuration is studied and a compression is made between them. An estimate of shear transfer length which is an essential parameter in arriving at an appropriate overlap length in patch design is proposed from DIC and FEA. Damage development, failure mechanism and load displacement behavior is also investigated. The experimental results are compared with the numerical predictions.

Leadscrew is used to translate turning motion into linear motion. The alternative stress is happening during the motion, and fatigue may happen when the leadscrew undergoes reciprocating motion.The purpose of this study is to measure the deformation of leadscrew in-service by digital image correlation method (DIC) for fatigue failure evaluation. The leadscrew was undergoing reciprocating motion, and the deformed leadscrew images were captured by a CCD camera. Full-field strain of the deformed leadscrew was obtained by using digital image correlation, and to further obtain the full-field stress. The deformation at several points were examined. The results show that at the points of concentrated stress, the maximun Von Mises stress is about four times bigger than that at the other points, and fatigue may be occured.

The marriage of optics and MEMS has resulted in a new category of optical devices and systems that have unprecedented advantages compared with their traditional counterparts. As an important spatial light modulating technology, diffractive optical MEMS obtains a wide variety of successful commercial applications, e.g. projection displays, optical communication and spectral analysis, due to its features of highly compact, low-cost, IC-compatible, excellent performance, and providing possibilities for developing totally new, yet smart devices and systems. Three most successful MEMS diffraction gratings (GLVs, Polychromator and DMDs) are briefly introduced and their potential applications are analyzed. Then, three different MEMS tunable gratings developed by our group, named as micro programmable blazed gratings (μPBGs) and micro pitch-tunable gratings (μPTGs) working in either digital or analog mode, are demonstrated. The strategies to largely enhance the maximum blazed angle and grating period are described. Some preliminary application explorations based on the developed grating devices are also shown. For our ongoing research focus, we will further improve the device performance to meet the engineering application requirements.

This paper demonstrates an approach to vibration energy harvesting using contact electrification or triboelectric mechanism. The device uses a cantilever to realize the contact electrification process when subjected to external vibrations. The device utilizes stiffening in the cantilever beam introduced by contact between two triboelectric layers to broaden the bandwidth of the vibrational energy harvester. The operating bandwidth of the energy harvester is shown to increase from 4.4 Hz to 17.8 Hz at RMS output voltage level of 60mV. The device was also observed to demonstrate continuous improvement in bandwidth as the acceleration level increased.

We experimentally demonstrate a switchable metamaterial absorber for infrared spectral region using MEMS technology. In order to achieve active tunability; air gap is introduced as the part of dielectric spacer layer and is electrostatically actuated. As the air gap is decreased, the peak absorption wavelength will blue shift accordingly. The tuning range is approximately 700 nm for 300 nm air gap change. Complementary cross is used as the metamaterial unit cell pattern. Owing to the π/2 rotational symmetry of the metamaterial unit cell geometry and out of plane actuation direction of the metamaterial layer, the resultant absorption retains the polarization insensitive characteristics at different actuation states. Additionally high temperature stable materials such as, molybdenum and silicon-di-oxide are used as structural materials for potential use in rugged applications.

The tunable terahertz metamaterial (TTM) has attracted intense research interest, since the electromagnetic response of the metamaterial can be actively controlled through external stimulus, which is of great significance in real time applications. The active control of metamaterial characteristics is crucial in order to provide a flexible and versatile platform for mimicking fundamental physical effects. To realize the electromagnetic tunability, various approaches have been demonstrated to increase the flexibility in applications, such as changing the effective electromagnetic properties. Alternatively, MEMS-based techniques are well developed. The structural reconfiguration is a straightforward way to control the electromagnetic properties. The metamaterial properties can be directly modified by reconfiguring the unit cell which is the fundamental building block of metamaterials. Currently, our research works are focusing on MEMS-based TTM adopting stress-induced curved actuators (SICA) to adjust the resonant frequency of devices. Herein, the proposed TTM designs are double split-ring resonator (DSRR), electric split-ring resonator (eSRR), Omega-ring metamaterial (ORM), symmetric and asymmetric T-shape metamaterial (STM and ATM), respectively. We demonstrated these TTM can be active, continuous, and recoverable control the resonant frequency by using electrostatic or electrothermal actuation mechanism. Therefore, the TTM devices can be effectively used for sensors, optical switches, and filters applications.

Syntactic foams are one of the special kinds of composite materials which can be prepared in a mechanical way by mixing hollow particles (the filler) with a resin system (the binder). To improve the mechanical properties of syntactic foams, in our work, carbon nanofibers (CNFs) were added to reinforce the syntactic foam. Results showed that although the presence of carbon nanofiber improved the mechanical properties of the syntactic foam, it dramatically increased the density, i.e., destroyed the main advantage of syntactic foams. In addition, the introduction of CNFs could cause difficulty in fabrication and increase the production cost. In order to overcome these problems, two approaches of the surface treatment of hollow microspheres, namely coupling agent and polydopamine (PDA) coating, were applied. Results showed that better interfacial adhesion between hollow microspheres and matrix could be induced from both coupling agent and PDA treated hollow microspheres, which led to the enhancement in mechanical properties of the syntactic foam while maintaining their low density. Compared with the coupling agent approach, the facile one-step PDA coating was much more effective. The failure mechanisms of the CNFs reinforced syntactic foam (CNFRSF) and the syntactic foam containing treated hollow microspheres were discussed in detail.

This paper demonstrated a simple approach for the development of advanced Nylon 12 composites by selectively modified multiwalled carbon nanotubes (MWCNTs). Prior mixing with Nylon 12, MWCNTs were modified by a nonsolvent process namely plasma treatment in order to improve its dispersion in the nylon matrix and enhance the interfacial adhesion by increasing the compatibility. A new combination of plasma treatment have been found through extensive investigations that led the nanocomposites to be extremely strong and tough even at moderately low amount of CNTs loading. Addition of only 1 wt % of modified MWCNTs, improved the tensile strength, Young’s modulus and elongation at break of the nanocomposites by ~ 65%, 61% and 68%, respectively. The FESEM images of fracture surfaces of nanocomposites showed excellent adhesion and dispersion of CNTs within the matrix, indicating the high merit of our selective plasma treatment process. Keywords: Plasma, Interface, Young’s modulus,

Glass Fiber Reinforced Polymer (GFRP) materials are extensively used in the aerospace and marine industries because of their high strength and stiffness to weight ratio and excellent corrosion resistance. Stiffened panels are commonly used in aircraft wing and fuselage parts. The present study focuses on the behavior of composite stiffened panels under compressive loading. With the introduction of stiffeners to unstiffened composite plates, the structural stiffness of the panel increases resulting in higher strength and stiffness. Studies in the past have shown that the critical structural failure mode under compressive loading of a stiffened composite panel is by local buckling. The present study attempts to evaluate the mechanical behavior of composite stiffened panels under compression using blade stiffener configuration and in particular on the behavior of the skin- stiffener interface through experimental testing. A novel test fixture is developed for experimental testing of GFRP stiffened panels. A non-contact whole field strain analysis technique called digital image correlation (DIC) is used for capturing the strain and damage mechanisms. Blade stiffeners increased the strength, stiffness and reduced the out-of plane displacement at failure. The failure of both the unstiffened and stiffened panels was through local buckling rather than through material failure. DIC was able to capture the strain localization and buckling failure modes.

The present study describes the burst behavior of aluminum liner based prototype filament-wound hybrid riser under internal hydrostatic pressure. The main objective of present study is to developed an internal pressure test rig set-up for filament-wound hybrid riser and investigate the failure modes of filament-wound hybrid riser under internal hydrostatic burst pressure loading. The prototype filament-wound hybrid riser used for burst test consists of an internal aluminum liner and outer composite layer. The carbon-epoxy composites as part of the filament-wound hybrid risers were manufactured with [±55^o] lay-up pattern with total composite layer thickness of 1.6 mm using a CNC filament-winding machine. The burst test was monitored by video camera which helps to analyze the failure mechanism of the fractured filament-wound hybrid riser. The Fiber Bragg Grating (FBG) sensor was used to monitor and record the strain changes during burst test of prototype filament-wound hybrid riser. This study shows good improvements in burst strength of filament-wound hybrid riser compared to the monolithic metallic riser. Since, strain measurement using FBG sensors has been testified as a reliable method, we aim to further understand in detail using this technique.

Understanding the changes in microcirculatory flow and its measurements are very important for assessing the progress of various vascular malfunctions and their subsequent treatment effectiveness. Laser Speckle Contrast Imaging (LSCI) has been evolved as a whole-field, non-invasive and non-contact technique which has inherent advantages for microcirculation assessment in an in vivo environment compared to its noninvasive counterparts such as laser Doppler technique and video capillaroscopy. However, representation of flow velocity values in absolute units is still challenging and yet to be completely explored. In this paper, we propose an experimental model for estimating the flow velocity based for optimum camera exposure time. The LSCI experiments were conducted on a custom made phantom flow channel with induced flow in the microcirculation range using a syringe pump. The speckle image contrast was estimated temporally and is used to calculate velocity values. The relative error in the flow values is estimated to be a function of the calculated contrast. The estimated error has been incorporated as a correction factor in the obtained velocity term using LSCI and final velocity estimation was found to be within an acceptable error range independent of the flow velocity and scatterer concentration of the sample for optimum camera exposure duration.

A new scheme to measure the glucose concentration with scatters is proposed for the detection of diabetics. In this study, the measuring technique based on the Stokes-Mueller polarimetry to solve the Mueller matrices of a complex sample containing circular birefringence and depolarization is developed. As a result, the circular birefringence and depolarization which relate to the concentrations of glucose and scattering events in turbid media can be inversely extracted.

A fibre optic sensor was developed for in-situ pressure measurement based on the principle of differential pressure in liquids. This sensor system is very simple and consists of fibre Bragg grating (FBG) done on a fibre with core diameter of 9 μm. A calibration study was carried out with a water column and the pressure sensitivity was found to be 1.636 × 10^-2MPa^-1. The results show that response of FBG to the rise of water level is linear and agrees well with the theoretical results. The reliability of the sensors is confirmed by repeating the measurements for three times. The sensor is useful in applications that involve in-situ resin pressure measurement in manufacturing of laminated composite materials.

Generally there are two categories of noncontact laser interferometric methods commonly used in dynamic measurement, camera-based full-field interferometry and photo-sensor-based laser Doppler interferometry. The two methods have different advantages and disadvantages thus are suitable for different applications. The camera-based interferometry enjoys the valuable merit of full-field observation and measurement. In this paper, one typical full-field interferometry, digital holography, is employed to monitor the growth process of aqueous sodium chlorate crystals. The phase proportional to the solution concentration is retrieved from the holograms captured by CCD camera in real time. There exist no phase ambiguity problem in holography compared with other optical interferometric methods. On the other hand, laser Doppler interferometry is usually a point-wise measurement but with a very high temporal sampling rate. A multipoint laser Doppler interferometer is proposed for modal parameter measurement in this paper. The multiple transient vibration signals of spatially separated points on a beam structure subjected to a shock excitation are recorded synchronously. The natural frequencies and mode shapes are extracted in the signal processing stage. This paper shows that laser interferometry is able to contribute more to the practical applications in dynamic measurement related fields.

Thermoelastic Stress Analysis (TSA) has been proposed as a method of obtaining residual stresses. The results of a preliminary study demonstrated that when Al-2024 plate containing holes that were plastically deformed by cold expansion process to 2% and 4% strain the thermoelastic response in the material around the hole was different to that obtained from a plate that had not experienced any plastic cold expansion (i.e. a reference specimen). This observation provides an opportunity for obtaining residual stresses based on TSA data. In many applications a reference specimen (i.e. residual stress free specimen) may not be available for comparison, so a synthetic, digital bitmap has been proposed as an alternative. An elastic finite element model is created using commercially available software Abaqus/Standard and the resultant stress field is extracted. The simulated stress field from the model is mapped onto a grid that matches the TSA pixel data from a physical reference specimen. This stress field is then converted to a ΔT/T field that can be compared to the full-field TSA data. When the reference experimental data is subtracted from the, bitmap dataset the resultant ΔT/T field is approximately zero. Further work proposes replacing the experimental reference data with that from specimens that have undergone cold expansion with the aim of revealing the regions affected by residual stress through a departure from zero in the resultant stress field. The paper demonstrates the first steps necessary for deriving the residual stresses from a general specimen using TSA.

Particle impact drilling (PID) using high-speed spherical carbide steel particles to impact rock and mechanical breaking of rock as a supplement, it is a new drilling method of breaking rock. Effects of rock fragmentation were studied by different injection speed of particles, injection angle and particle diameter based on ANSYS simulation platform. The two basic types of nozzles were studied, straight-taper nozzle model and streamline nozzle model, the mathematical model of nozzle were established based on the acceleration mechanism of solid-liquid two-phase flow, and an optimized nozzle structure is designed. A rock breaking experiment device used to simulate particle impact drilling was developed. The experimental investigations were carried out by controlling the drilling parameters such as particles injection speed, injection angle, the ratio of metal particles, drilling speed and weight on bit(WOB), etc. to study the effects of rock breaking based on this experiment device. The results show that the device can simulate the rock fragmentation process of particle impact drilling completely, it proves that technological requirements of high efficiency of breaking rock can be achieve well with particle whose diameter is 1mm, shot speed 120 m/s, it also verified the theoretical analysis of fragmentation efficiency of rock for different volume fraction and jetting angle. The test provide technical support for the popularization and application of the technology.

This paper develops a set of projection Moiré system. It projects the grating onto the surface of specimen and forms grid lines of which the pitch is adjustable on large area through light source and projection grating. At the same time, the imaging system images the grid lines precisely onto the reference grating and then the Moiré fringes are formed. The modulation of out-of-plane displacement to grid lines transform into the distortion of Moiré fringes. The greatest advantage of this projection Moiré system is that what the CCD camera captures is the Moiré fringes, not the gird lines. The Moiré fringes can magnify the variation of out-of-plane displacement of the specimen with no distortion and the measuring resolution is improved a lot. Besides, this system is appropriate for large area measurement by using a wide-angle lens in imaging system. The full-field out-of-plane displacement can be acquired through image processing. The measuring resolution of this system can reach 10μm on a large area of 3m*3m.

In this paper, the flexural behavior was investigated at different temperatures and different cross-head speeds with and without diffusion effect. The studied material is carbon fiber reinforced derakane epoxy composite. The testing temperature was set at 30, 50, 80 and 100°C to investigate the temperature effect on flexural strength. At each temperature, the testing was conducted at four different cross head speeds (0.05, 0.2, 2 and 20mm/min). The diffusion effect was studied on flexural strength with specimens soaked in sea water at 50°C to saturate. A master curve of flexural strength was formed based on time-temperature superposition principle (TTSP) with shift factor obtained by DMA test. Based on the master curve, the flexural strength was predicted with a 35% drop after using 30 years in an ideal condition without considering pressure, stress, diffusion and so on.

Since composite material is playing an increasingly important role in the marine and offshore drilling industry, it is essential to have a good understanding on degradation of the material in the seawater environment. This study investigates the influence of seawater exposure on the mechanical and failure behavior of E-Glass/BMI composite. The water diffusion behavior in the composite has been studied through immersing the specimens in seawater under different conditions. The diffusion rate accelerates with increase of temperature, and the material shows irreversible damage due to seawater absorption at the temperature of 80°C. It is also found that external stress would significantly increase the water absorption. The water uptake in the specimen at 50°C showed a two stage behavior dominated by Fickian law and polymeric relaxation respectively, and saturation was not achieved in 8 months. After diffusion, the T_g of the material is considerably lowered due to plasticization effect. However the effect was found to be reversible after drying the specimen. Based on the testing results of tensile, flexure and fatigue properties of the composites, it is concluded that seawater exposure especially at elevated temperature leads to significant degradation on mechanical properties of the composite. However, the flexural strength of BMI composite with seawater absorption becomes less susceptible to temperature change. It is also found that the seawater absorption doesn't show significant effect on the stiffness of the material.

Accurate and wide-range shape measurement method is required in industrial field. The same technique is possible to be used for a shape measurement of a human body for the garment industry. Compact 3D shape measurement equipment is also required for embedding in the inspection system. A shape measurement by a phase shifting method can measure the shape with high spatial resolution because the coordinates can be obtained pixel by pixel. A key-device to develop compact equipment is a grating projector. Authors developed a linear LED projector and proposed a light source stepping method (LSSM) using the linear LED projector. The shape measurement euipment can be produced with low-cost and compact without any phase-shifting mechanical systems by using this method. Also it enables us to measure 3D shape in very short time by switching the light sources quickly. A phase unwrapping method is necessary to widen the measurement range with constant accuracy for phase shifting method. A general phase unwrapping method with difference grating pitches is often used. It is one of a simple phase unwrapping method. It is, however, difficult to apply the conventional phase unwrapping algorithm to the LSSM. Authors, therefore, developed an expansion unwrapping algorithm for the LSSM. In this paper, an expansion algorithm of measurement range suited for 3D shape measurement using two pitches of projected grating with the LSSM was evaluated.

The citric acid (CA) coated Fe₃O₄ ferrofluids are prepared by a co-precipitation method and the magneto-optical retardance property is measured by a Stokes polarimeter. Optimization and multiple regression of retardance in ferrofluids are executed by combining Taguchi method and Excel. From the nine tests for four parameters, including pH of suspension, molar ratio of CA to Fe₃O₄, volume of CA, and coating temperature, influence sequence and excellent program are found. Multiple regression analysis and F-test on the significance of regression equation are performed. It is found that the model F value is much larger than Fcritical and significance level P <0.0001. So it can be concluded that the regression model has statistically significant predictive ability. Substituting excellent program into equation, retardance is obtained as 32.703°, higher than the highest value in tests by 11.4%.

This paper introduces iFringe, a mobile application that attempts to incorporate the resource heavy fringe analysis algorithms into the smart mobile devices platform. This first step taken towards mobility in the optical processing field aims to become a catalyst for modernization of various aspects of the field as well as to diversify developments to other applications. Predominantly, the motivation of this work stems from the vastly indifferent human interactive method of mobile devices, which enable images displayed on its touch screen to be manipulated in ways that could enhance the fringe analysis experience. Furthermore, given its hardware compatibility to the conventional fringe projection system, these mobile devices could potentially serve as a much more compact replacement. However, one imperative weakness that mobile devices pose is its limited computing ability. Therefore, to examine the feasibility of incorporating the fringe analysis algorithms into a mobile platform, we have implemented two fundamental fringe analysis techniques, namely the Fourier transform fringe analysis method and the phase-shifting technique. Formulas and processing procedures such as discrete Fourier transform (DFT) and quality-guided phase unwrapping, were included in accordance to their original algorithms to test their performance and usability on a smart mobile device. Details of the implementation and the performance results will also be presented in this paper to demonstrate the practicality of these algorithms on the smart mobile device platform.

Virtual reality (VR) has proved to be a particularly useful tool in engineering and design. A related area of aviation in which VR is particularly significant is a flight training, as it requires many hours of practice and using real planes for all training is both expensive and more dangerous. Research conducted at the Rzeszow University of Technology (RUT) showed that virtual reality can be successfully used for planning experiment during a flight tests. Motivation to the study were a wing deformation measurements of PW-6 glider in flight by use Image Pattern Correlation Technique (IPCT) planned within the frame of AIM² project. The tool VirlIPCT was constructed, which permits to perform virtual IPCT setup on an airplane. Using it, we can test a camera position, camera resolution, pattern application. Moreover performed tests on RUT indicate, that VirlIPCT can be used as a virtual IPCT image generator. This paper presents results of the research on VirlIPCT.

The packer is the key element in separating geosphere layers of water injection, water plugging and fracturing operations in the oilfield. The sealing ability of the packer is depending on the contact pressure between rubber tube and the casing. The circumferential strain of casing wall was tested by the strain gauge to get the contact pressure distribution along axial direction of the tube. The friction force between the casing and the rubber tube was taken by the pressure sensor in compression process. Under the 20,60 and 100 degrees Celsius conditions, the friction forces and the contact pressure distribution were taken in work condition of single rubber tube, double rubber tubes and combination rubber tubes after oil immersion .The result shows that elastic modulus of rubber tube has little effect on the friction force and contact pressure. With elastic modulus decreasing, the friction forces has gradually decreasing trend; The friction coefficient has much impact on friction force: the friction forces under the condition of dry friction and wet friction are respectively equivalent to 48.27% and 5.38% axial compression forces. At wet friction condition, the contact pressure distribution is more uniform and the sealing effect is better.

In this study, a method for evaluating a fracture parameter, J-integral, for an interface crack from the displacement fields under thermal deformation is developed for studying the fracture behavior of an interface crack in an actual electronic component. First, the displacement fields around an interface crack tip are measured using digital image correlation (DIC). Second, the displacement gradient and strain are determined from the displacement fields using a finite element smoothing technique on the domain of integration. Then, the stress components are determined from the strains using the elastic-plastic relations with the incremental strain theory and the each material property. Finally, the J-integral value is determined by the numerical integration on the domain of integration. The effectiveness of this evaluation method is demonstrated by applying this method to the displacement fields obtained from the elastic-plastic finite element analysis.

The key to enhancing oil recovery of very high water cut oilfield lies in analyzing oil displacement efficiency in different position of reservoir, which mainly focus on the analysis of dimensionless cumulative flowing into water volume and oil displacement efficiency distribution. In order to get the oil displacement efficiency distribution characteristics to future analyze influence on oil displacement efficiency by changing well pattern, oil displacement efficiency in different position of homogeneous reservoir is studied by combining the analysis of core displacement experiment with oilfield practice in this paper. Firstly, streamline function and streamline distribution between injection-production well in homogeneous reservoir is researched by the potential function and potential distribution with the five-point well pattern. Secondly, the method of flow distribution on the streamline between the injection-production well is studied according to change law of seepage resistance. Thirdly, dimensionless cumulative flowing into water volume along the streamline is calculated based on the core size to analyze its distribution characteristics about homogeneous reservoir and obtain dimensionless cumulative flowing into water volume at different position of the reservoir matching the core displacement experiment. Finally, the distribution characteristics of oil displacement efficiency are got by statistical analysis for the change of oil displacement efficiency as the dimensionless cumulative flowing into water volume in real oilfield. This study may provide technical measure with oilfield enterprise to enhance the oil recovery of very high water cut oilfield.

Masonry being a composite system is very complex to study with analytical methods alone. Quantitative digital photoelastic analysis using Three Fringe Photoelasticity (TFP) is carried out on a model of a dry masonry wall with bricks made up of epoxy, loaded with a concentrated load. The result obtained provides insight into the micromechanics of force transmission and interactions between bricks in masonry. The result shows that force transmission through the wall occurs at discrete points. A tree like hierarchical pattern of stress flow is observed. It is also observed that the stress percolation results in the existence of stress-free zones in the model domain.

Birefringence affects the quality of image analysis in injection molded micro-plates. Depending upon their manufacturing / production processes and the type of material, different plates exhibit varying amounts of birefringence. This birefringence is attributed to residual stress generated during the molding process. Polarimeter is the standard tool for birefringence distribution visualization and quantification. Broad chemical resistance and high mechanical stability of the plates are the desirable properties that can be characterized by birefringence measurement. Birefringence, expressed in nm/cm is light retardance (nm) after passing through a sample with certain thickness (cm). Low or uniform birefringence plates provide high-resolution demonstrating higher performance, hence suitable for bio-chemical analysis.

Friction coefficient between a circular-disk periphery and V-block surface was determined by introducing the concept of isotropic point (IP) in isochromatic field of the disk under three-point symmetric loading. IP position on the symmetry axis depends on active coefficient of friction during experiment. We extend this work to asymmetric loading of circular disk in which case two frictional contact pairs out of three loading contacts, independently control the unconstrained IP location. Photoelastic experiment is conducted on particular case of asymmetric three-point loading of circular disk. Basics of digital image processing are used to extract few essential parameters from experimental image, particularly IP location. Analytical solution by Flamant for half plane with a concentrated load, is utilized to derive stress components for required loading configurations of the disk. IP is observed, in analytical simulations of three-point asymmetric normal loading, to move from vertical axis to the boundary along an ellipse-like curve. When friction is included in the analysis, IP approaches the center with increase in loading friction and it goes away with increase in support friction. With all these insights, using experimental IP information, friction angles at three contact pairs of circular disk under asymmetric loading, are determined.

The non-intrusive in-flight measurement of the deformation and pitch of the aircraft propeller is a demanding task. The idea of an imaging system integrated and rotating with the aircraft propeller has been presented on the 30^th International Congress on High-Speed Imaging and Photonics (ICHSIP30) in 2012. Since then this system has been constructed and tested in the laboratory as well as on the real aircraft. In this paper we outline the principle of Image Pattern Correlation Technique (IPCT) based on Digital Image Correlation (DIC) and describe the construction of a dedicated autarkic 3D camera system placed on the investigated propeller and rotating at its full speed. Furthermore, the results of the first ground and in-flight tests are shown and discussed. This development has been found by the European Commission within the 7^th frame project AIM² (contract no. 266107).

Conventional non-destructive inspection of a pipe by ultrasonic wave has difficulty with inspection efficiency because it is a technique to apply by using longitudinal wave or transverse wave which propagates to the thickness direction of a pipe for smaller area than an ultrasonic sensor. However, a guide wave is provided with a characteristic of long-range propagation to the axis direction of a pipe, so it is possible to detect a lot of defects through wide range of a pipe at once. At present, there is a technique to generate a guide wave by a piezoelectric element (PZT). Such transducer has some difficulties to use in industrial application, which is required high viscosity couplant. Therefore we tried to develop a guide wave inspection system to use an electromagnetic ultrasonic transducer (EMAT) which doesn’t require any couplant. First, we could confirm that guide wave can be transmitted and received in aluminum pipe by a shear horizontal polarized-EMAT, and we have confirmed the most suitable transmission and reception EMAT-specification and the most suitable drive condition to generate for L, T and F-mode guide wave. Finally, we have evaluated the detective performance using the developed system.

Non-destructive inspection using ultrasonic sensors is widely utilized to guarantee the safety of large structures. However, there is the problem that it will take a very long time to complete. Therefore, it was decided to develop a sensor capable of testing a wide range of structures at a high inspection speed. The ultrasonic wave that the ultrasonic sensor can generate must be equally emitted in any direction and the ultrasonic wave returned from any direction be detected. To attain this objective, an electromagnetic acoustic transducer (EMAT) consisting of a circular-shaped magnet and an electric induction coil (EM) has been developed, because it is impossible to fabricate such a special ultrasonic sensor using a commercial-type ultrasonic sensor with a piezoelectric element, and it is convenient to automatically scan over the surface of the structure. First, the detail specifications of the new ultrasonic sensor have been determined by changing many of the parameters, for example, the impedance and the size of the EM coil, the size of the magnet, etc. The performance of the new sensor was then tested under different conditions. Based on the results of the experimental tests, it was demonstrated that the new sensor could generate ultrasonic waves in any direction and detect them from any direction. However, the performance was not high enough to apply the new sensor to a real structure. The new sensor has been improved to increase the performance by adding a new concept.

Fibre Metal Laminate (FML), a metal sandwiched hybrid composite material is well-known for its enhanced impact properties and better damage tolerance and it has been successfully implemented in diverse engineering applications in aviation industry. With heterogeneous constituents, the stacking sequence of FML is believe to play a critical role to govern its overall energy absorption capability by means of controlling delamination of metal composite interface and plastic deformation of metal layers. As a precursor, low velocity impact experiments were conducted on interply configured transparent plastic plates in order to extract the significance of stacking sequence and realize the characteristics of each layer through naked eye which is not possible in FML due to opacity of metal layer. The stack configuration constitute hard acrylic (brittle) and soft polycarbonate (ductile) plates analogous to composite (brittle) and metal (ductile) layers on FML laminate and the impact event is performed on either hard or soft facing sides separately. Hard side samples resemble more protective than soft side impact sample, with large peak resistant force and expose smaller damage growth in all experimented cases.

The active deformable lap (also namely stressed lap) is an efficient polishing tool in optical manufacturing. To measure the dynamic deformation caused by outside force on a deformable lap is important and helpful to the opticians to ensure the performance of a deformable lap as expected. In this paper, a manual deformable lap was designed to simulate the dynamic deformation of an active stressed lap, and a measurement system was developed based on inverse projected fringe technique to restore the 3D shape. A redesigned inverse fringe has been projected onto the surface of the measured lap, and the deformations of the tested lap become much obvious and can be easily and quickly evaluated by Fourier fringe analysis. Compared with the conventional projection, this technique is more obvious, and it should be a promising one in the deformation measurement of the active stressed lap in optical manufacturing.

Nowadays, 3D face recognition has become a subject of considerable interest in the security field due to its unique advantages in domestic and international. However, acquiring color-textured 3D faces data in a fast and accurate manner is still highly challenging. In this paper, a new approach based on color speckle projection for 3D face data dynamic acquisition is proposed. Firstly, the projector-camera color crosstalk matrix that indicates how much each projector channel influences each camera channel is measured. Secondly, the reference-speckle-sets images are acquired with CCD, and then three gray sets are separated from the color sets using the crosstalk matrix and are saved. Finally, the color speckle image which is modulated by face is captured, and it is split three gray channels. We measure the 3D face using multi-sets of speckle correlation methods with color speckle image in high-speed similar as one-shot, which greatly improves the measurement accuracy and stability. The suggested approach has been implemented and the results are supported by experiments.

In this paper, low-speed smoke wind tunnel has been designed and fabricated for the insects’ flow field visualization. The test section and the contraction section of the tunnel are optimized and determined as to size by the method of computational fluid dynamics. And fairing devices are equipped in different sections to reduce the turbulence intensity and increase the flow uniformity in the experimental sections. For the smoke visualization of small insects, the smokeemitting equipment has been specially designed and carefully debugged. Composed of wind tunnel, light source and high-speed camera, experimental platform for visualization and filming of insect flight flow field has been established. Besides, the feasible and stable method for insect fixing has been designed. With the smoke wind tunnel, flow filed visualization experiment for the honeybee’s flapping was conducted and smoke flow filed in the experiment was recorded and analyzed. Near-filed and far-filed vortex structure when the honeybee fly can be recorded clearly. The experimental results indicate that the experimental platform is appropriate for flow filed study on insects flapping.

This paper reports an experimental investigation on the motion of a circular cylinder after it horizontally enters into a water flow with a certain slamming speed. A smart cylinder-releasing mechanism is designed to enable repeatable release of the cylinder. A high-speed camera is used to record the cylinder’s motion. The effects of three factors are investigated, including the cylinder-to-water density ratio, water speed and slamming speed of the cylinder. Data for several cases with either a solid cylinder or a hollow cylinder are obtained and compared. Variations of both horizontal and vertical displacements against these factors are presented and analyzed. It is found that the trajectories of the hollow cylinder collapse at the initial stage of submerging in water when the velocity ratios are the same.

A new method to measure the tensile adhesion of thin film was proposed. A single cantilever beam method was used and an efficient adjustable jig was designed to minimize errors induced by misalignment of specimen. Applied load and displacement were recorded by data acquisition system. The dimensions of the specimen and conditions of test were preexamined by finite element analysis. Developed method was applied to measure the adhesion of thin film adhesive. Test results were independent of initial deviation of specimen alignment and showed consistent value with respect to crack length. Compared with shear test method, it was shown that the shear adhesion included the effect of thickness of adhesive, however, tensile adhesion was independent of the thickness of adhesive.

The special designed 3-DOF direct-drive air bearing decoupling stage has the advantages of high repeatability and free coupling error between different axes. And it is suitable for wafer scanning application. However, due to the flexible joints between the orthogonal axes, the relatively low frequency resonant modes limit the bandwidth of closed loop tracking control. This presentation shows how we obtain the frequency response model of the decouple stage accurately and safely with closed-loop identification approach, using dSPACE modular control systems, and how we use the model to achieve high-speed tracking control using model-based feedforward / feedback composite control. For safety purposes, the electrical portion of decoupled stage is carefully designed with appropriate limit sensors and emergency safety switch. The decoupled stage is controlled by DS1005 modular control system, which gives ultra-high control loop updating rate at 100us. With such high profile controller, we model the frequency response of 3-DOF system using sequential closed-loop relay feedback. From here, the model of rigid body mode and flexible modes are identified. The identified model provides a guideline for trajectory design and closed-loop PID plus feedforward controller design for synchronization of dual-drive X-axis motion. Although the trial on design of decoupling controller has been proposed, internal stability of such decoupling control schemes remains a research issue for our future work.

Montmorillonite (MMT) was first cation exchanged by cetyltrimethyl ammonium bromide (CTAB) and then treated by short chain silane (methyltrimethoxylsilane) or different amount of long chain silane (dodecyltrimethoxylsilane). High density polyethylene (HDPE)/clay nanocomposites were prepared through twin screw extruder using these silane modified clays without any compatibilizer. Thermal gravimetric analysis (TGA) proved the successful grafting of silanes onto clay. The effects of the chain length and content of the silanes on the dispersion state of clay and properties of the composites were studied using X-ray diffraction (XRD), transmission electron microscope (TEM), mechanical tests, creep tests and so on. The results indicate that the grafting of long chain silanes at higher content could improve the compatibility between clay and PE, thus more efficiently enhancing mechanical and creep properties of the composites than other silane treated clays.

This paper describes the design and electro-mechanical characterizations of a three-axial micro piezoresistive force sensor fabricated by microelectromechanical systems (MEMS) technologies. This is the first three-axial MEMS micro force sensor applied to the study of Micro Aerial Vehicle (MAV) aerodynamics. A standard dry etching fabrication process using Silicon On Insulator (SOI) wafer is employed to fabricate the multi-axis sensors. Conventional cross-beam structure is employed. There are eight piezoresistors on the beams, and each of the silicon strain gauge size is 15 μm in width, and between 400 and 500 μm in length. The Finite Element Method (FEM) analysis for confirming the piezoresistors attachment locations is performed. The miniaturized force sensor (11×11 mm²) is attached at the wing base of a micro flapping wing system (MAV, 70×30 mm² ) by a short pillar. The sensor is designed to detect the dynamic drag force and lift force generated by a single wing under a moderate flapping frequency (5~10Hz) simultaneously. The characterizations are experimentally investigated. The sensor should be stiff enough to withstand the high inertial force (200 millinewton) and also has high resolution to detect the minimal force correctly. Measurements show that the resolution is on the order of a millinewton. High linearity and low hysteresis under normal forces and tangential forces are demonstrated by applying forces from 0 to 0.1 N. The micro flapping wing mechanism and the assembly of wing and sensor are also discussed in this paper.

Phase unwrapping is a process to reconstruct the absolute phase from a wrapped phase map whose range is (−π, π]. As the absolute phase cannot be directly extracted from the fringe pattern, phase unwrapping is therefore required by phasemeasure techniques. Currently, many phase unwrapping algorithms have been proposed. In this paper, four popular phase unwrapping algorithms, including the Goldstein’s branch cut method, the quality-guided method, the Phase Unwrapping via Max Flow (PUMA) method, and the phase estimation using adaptive regularization based on local smoothing method (PERALS), are reviewed and discussed. Detailed accuracy comparisons of these methods are provided as well.

A novel quantitative 3D imaging system of silicon microstructures using InfraRed Transport of Intensity Equation (IRTIE) is proposed in this paper. By recording the intensity at multiple planes and using FFT or DCT based TIE solver, fast and accurate phase retrieval for both uniform and non-uniform intensity distributions is proposed. Numerical simulation and experiments confirm the accuracy and reliability of the proposed method. The application of IR-TIE for inspection of micro-patterns in visibly opaque media using 1310 nm light source is demonstrated. For comparison, micro-patterns are also inspected by the contact scanning mode Taylor Hobson system. Quantitative agreement suggests the possibility of using IR-TIE for phase imaging of silicon wafers.

The digital shearograghy method has shown strong cutting edge in the whole-field measurement, the simple optical road, the easy modulation and the low demand for environment. Also the phase-shifting method which is used in digital shearograghy can improve the precision of the measurement greatly. And therefore these methods are used in Non Destructive Testing (NDT) widely. In this paper, the inner defect detection of pressure vessels was studied via the theoretical mode, the numerical simulation (finite element method) and the experiment in which the digital shearograhy and phase-shifting method was used. The first-order derivative maximum of the out-of-plane displacement in the defect which have different diameters and depths under the various pressures were obtained and compared with each other. And the results obtained with the three different means mentioned above are consistent. According to the maximum number of 1st derivation, the defect of pressure vessels is detected when the proportion of the diameter and the thickness of defect is the more than 9. In addition, the phase diagrams and the out-of-plane displacement gradients were also gained. Based on the phase diagram, it is easily determined whether the defect exists, and the defect relative size can be qualitatively obtained. It is proved that there is feasibility and advantage of the digital shearograghy when it is used in inner defect detection of pressure vessels. This study can provide a new method that is able to detect inner defects of pressure vessels and widen the application of the digital shearograghy.

Single wavelength microscopic speckle interferometry is widely used for deformation, shape and non-destructive testing (NDT) of engineering structures. However the single wavelength configuration fails to quantify the large deformation due to the overcrowding of fringes and it cannot provide shape of a specimen under test. In this paper, we discuss a two wavelength microscopic speckle interferometry using single-chip colour CCD camera for characterization of microsamples. The use of colour CCD allows simultaneous acquisition of speckle patterns at two different wavelengths and thus it makes the data acquisition as simple as single wavelength case. For the quantitative measurement, an error compensating 8-step phase shifted algorithm is used. The system allows quantification of large deformation and shape of a specimen with rough surface. The design of the system along with few experimental results on small scale rough specimens is presented.

Many of the early occurring micro-anomalies in breast may transform into a deadliest cancer tumor in future. Probability of curing early occurring abnormalities in breast is more if rightly identified. Even in mammogram, considered as a golden standard technique for breast imaging, it is hard to pick up early occurring changes in the breast tissue due to the difference in mechanical behavior of the normal and abnormal tissue when subjected to compression prior to x-ray or laser exposure. In this paper, an attempt has been made to estimate the stress relaxation time of normal and abnormal breast mimicking phantom using laser speckle image correlation. Phantoms mimicking normal breast is prepared and subjected to precise mechanical compression. The phantom is illuminated by a Helium Neon laser and by using a CCD camera, a sequence of strained phantom speckle images are captured and correlated by the image mean intensity value at specific time intervals. From the relation between mean intensity versus time, tissue stress relaxation time is quantified. Experiments were repeated for phantoms with increased stiffness mimicking abnormal tissue for similar ranges of applied loading. Results shows that phantom with more stiffness representing abnormal tissue shows uniform relaxation for varying load of the selected range, whereas phantom with less stiffness representing normal tissue shows irregular behavior for varying loadings in the given range.

In this paper we present a new method to compensate for phase aberrations and image distortion with recording single digital hologram in digital holographic microscopy. In our method, tilt is removed from the abberrated phase map first. Then an area of interest (AOI) is generated by flood filled algorithm. By fitting AOI with discrete orthogonal Zernike polynomials, error phase map in the form of a series of Zernike polynomials is obtained. Final result can be calculated by subtracting the error phase map from the abberrated phase map. Through applying our method in microlens testing, phase aberrations and image distortion introduced by microscope objective are well suppressed.

Collimation lenses for light-emitting diode (LED) light sources have been widely used in lighting engineering. In this study, a collimated LED light source was developed for a color liquid-crystal display backlight, which is driven using a two-field driving scheme to display color. A color-separation backlight that involves using the designed collimation modules possesses several advantages such as low volume, elimination of dye color filters, high feasibility with conventional ultraprecision machining processes, and a wide color gamut.

This paper designs a multiple reflectors based autocollimator, and proposes a direct linear solution for three-dimensional (3D) angle measurement with the observation vectors of the reflected lights from the reflectors. In the measuring apparatus, the multiple reflectors is fixed with the object to be measured and the reflected lights are received by a CCD camera, then the light spots in the image are extracted to obtain the vectors of the reflected lights in space. Any rotation of the object will induce a change in the observation vectors of the reflected lights, which is used to solve the rotation matrix of the object by finding a linear solution of Wahba problem with the quaternion method, and then the 3D angle is obtained by decomposing the rotation matrix. This measuring apparatus can be implemented easily as the light path is simple, and the computation of 3D angle with observation vectors is efficient as there is no need to iterate. The proposed 3D angle measurement method is verified by a set of simulation experiments.

Laser scanning head-up display (HUD) is an off-axis imaging virtual image display system. Its optical design inherited the feature of head-up display architecture in a fighter. When it is applied to a car, its main optics is replaced by a mirror to save space. Usually, a diffusion sheet or frosted glass is placed in front of a pico-projector to be an image screen, but there will be an issue of lower sharpness of the image due to its low divergence ability for the incident beam. This study proposes a pyramid-shaped micro-structure optical diaphragm to replace the above traditional diffusion films. Besides, the relationship between the optical light path and microstructure in the HUD is also well described.

White light interferometry (WLI) is a state-of-the-art technique for high resolution full-filed 3-D surface profiling of Microsystems. However, the WLI is rather slow, because the number of frames to be recorded and evaluated is large compared to the single wavelength phase shifting interferometry. In this paper, we combine white light interferometer with a single-chip color CCD camera which makes the measurement faster, simpler, and cost-effective. The red-bluegreen (RGB) color interferogram stored in a computer is then decomposed into its individual components and corresponding phase maps for red, green, and blue components are calculated independently. The usefulness of the technique is demonstrated on reflective micro-scale-samples.