This pdf file contains the front matter for SPIE Proceedings Volume 7522, including Title page, Copyright information, Table of Contents, Conference Committee listing, and Introduction (if any).

In this work, fracture behavior of unidirectional graphite/epoxy composite materials is optically investigated. Single-edge notched coupons are studied under geometrically symmetric impact loading. The notch orientation parallel to or at an angle relative to the fiber orientation is considered to produce mode-I as well as mixed-mode fracture. Stress-wave induced crack initiation and rapid crack growth events are studied using a digital correlation technique and high-speed photography. Surface deformations histories in the crack-tip vicinity are obtained by analyzing decorated speckle recordings. Measured deformation fields are used to extract fracture parameters and examine the effect of fiber orientation on crack initiation and growth behaviors. The maximum crack speed observed is the highest for mode-I dominant conditions and decreases with increasing fiber orientation angle. With increasing fiber orientation angle, crack takes longer to attain the maximum speed upon initiation. The crack initiation toughness values decrease with increasing degree-of-anisotropy.

Failures of engineering components caused by rolling contact fatigue, such as flaking in bearings, are closely related to the initiation and growth of share-mode, i.e. Modes II and III, fatigue cracks. In order to evaluate quantitatively the fatigue strength of those components, it is necessary to elucidate the propagation and threshold behaviors of share-mode cracks, particularly for small cracks, on the basis of fracture mechanics. In this study, fatigue tests of fully-reversed cyclic torsion superposed upon static compression were carried out using SAE52100 bearing steel shafts into which semi-elliptical cracks smaller than 1 mm in size were initially introduced in the axial direction. Propagation and nonpropagation of shear-mode fatigue cracks were controlled by changing the torsional stress amplitude. The threshold stress intensity factor (SIF) range for a share-mode crack was defined at the minimum stress required for crack propagation. Crack face interference was responsible for the reduction in crack driving force. An intrinsic value of threshold SIF range that does not include the effect of crack face interference was obtained to be approximately 13 MPa⁺m^0.5.

Due to the enhanced energy absorption characteristics, the steel fiber-reinforced concrete (SFPC) structures gains more and more attention in the civilian and military ballistic protection structures when comparing with the plain concrete (PC) ones. By comparison on the penetration depth, the crater volume on impact face of the target and the debris cloud topography, the resistance of PC and SFPC slabs against projectiles impacting was investigated experimentally in a two-stage light-gas gun. In order to more widespread understand the effect of steel fibers against projectiles impacting, five different types of concrete slabs were done in the range of unconfined compressive strength from ordinary to high. Through the analysis of the test results it was found that the incorporation of steel fibers in the concrete reduced the crater diameter and restrained the initiation and propagation of cracking, but did not have a significant effect on the penetration depth.

The acceleration of hydrogen diffusion in the fatigue process of AISI type 304 and 316L meta-stable austenitic stainless steels was studied by paying attention to the relation between fatigue slip bands and hydrogen emission. Slip bands were formed in tension-compression fatigue tests of round specimens in ambient air, and then the specimens were cathodically charged with hydrogen. The location of hydrogen emission was microscopically visualized by means of the hydrogen microprint technique (HMT). Hydrogen was mainly emitted from slip bands on the surface of fatigued specimens. The depth of hydrogen diffusion into the specimens was also observed on the fatigue fracture surfaces by the HMT. The depth for a specimen hydrogen-charged before fatigue testing was about 50 μm at a maximum, whereas the depth for a specimen that was hydrogen-charged after slip bands had been formed in a preliminary fatigue test was about 300 μm. Those results suggested that slip bands act as a pathway where hydrogen will move preferentially.

Axial-loading fatigue tests were carried out under low stress ratios, R = -∞ ~ -5.33, by use of a cylindrical specimen of SAE52100 bearing steel having drill holes of 50 ~ 200 μm in diameter. The maximum stresses, σ_max = 0 ~ 300 MPa were combined with the minimum stresses, σ_min of -1600 or -1800 MPa. Even at σ_max = 0, fatigue cracks were initiated at hole edges by cyclic compressive stress of σ_min = -1800 MPa, and the cracks finally became non-propagating. When σ_max was positive, fatigue cracks were initiated even at σ_min = -1600 MPa and they also became non-propagating. The length of non-propagating cracks increased with an increase in σ_max. Those phenomena were considered to be related to the tensile residual stress that was induced by the plastic deformation in the vicinity of hole edges. The relationship between the length of non-propagating crack and the residual stress field was investigated in terms of elastic-plastic finite element analysis.

This paper investigates fatigue strength and existence of mechanical damage experimentally and analytically. In particular, first, we carry out rotary bending fatigue tests and investigate fatigue strength for smooth specimens and specimen processed using the working method. Secondly, we measure Vickers hardness value to investigate strain hardening, and observe microstructure to investigate microstructure change in the diameter-enlargement part. Finally, we simulate stress and strain distribution in the processed part during the processing, using finite element method (FEM), and calculate stress concentration rate and plastic strain. And we predict the existence of mechanical damage in the processed part during the processing experimentally and numerical-analytically. The results of the experiments and analyses indicate that the fatigue damage is not generated in the processed part during the processing in the discussed range of the diameter-enlargement rate D/D₀<1.8, through comparing with the smooth specimens.

The photoviscoelastic material used in this paper was prepared by mixing the liquid form base material Epon 828, the hardener MHAC-P and the cure accelerator 2E4MZ in a weight ratio of 100:103.6:1. To avoid the solidifying flow lines appear on the surface of the specimen and the unevenness of the specimen, an innovative vertical type mould was designed to accommodate the mixed materials and execute the curing process. Test specimens were prepared by following the ASTM B 557M specifications. The uniaxial tensile relaxation test and constant strain-rate test were performed at eight constant temperatures, 25°C, 70°C, 100°C, 130°C, 145°C, 160°C, 175°C, and 190°C. Both tests were video recorded for later detailed analysis. The master curves of relaxation modulus and relaxation birefringence strain coefficient were obtained by applying the time-temperature superposition principle. Prony series, Langevin equation and Boltzmann equation were used to fit those master curves. It was found that Boltzmann equation gave the most satisfactory results of fitting. After integrating the fitted Boltzmann equation with the photoviscoelastic theory, the time-varying stress field of the viscoelastic material under investigation can be analyzed.

Digital photoelasticity is a whole field experimental technique which can analyze both 2-D and 3-D models. In this paper, stress frozen 3-D models are sliced mechanically and the whole field principal stress differences (Isochromatics) and principal stress directions (Isoclinics) are evaluated by capturing only five images using the standard optical arrangements of a conventional polariscope. The wrapped isoclinic values obtained by processing the first four colour polarization stepped images in the range -π/4 to +π/4 are unwrapped using adaptive quality guided phase unwrapping algorithm to get isoclinics in the range of -π/2 to +π/2. The total fringe order is evaluated by three fringe photoelasticity or RGB photoelasticity with its latest developments like colour adaptation combined with refined three fringe photoelasticity. The methodology is validated for two slices cut from aero-structural components.

Presently, most defective problems in silicon based devices can be traced ultimately to stresses developed during various fabrications process stages. If the process induced stresses exceed the critical stress magnitude, dislocations occur to relax the stain. Subsequently, other defects such as cracks, chips and void related to stresses may surface. Hence an understanding of the development, effects and possible avoidance of residual stress is vital and even more important for the semi-conductor industries as it goes into the nanometer technology. Whether process-induced, residual stress is a significant factor in high wafer breakage rates during microelectronic fabrication. Identifying the cause and initiation point of brittle fracture in processed wafers is an important first step towards the goal of making this and other newer technologies based on silicon commercially competitive. Infrared Phase Shift Gray Field which has showed some promises on residual stress measurement on silicon devices ranging from microelectronics to photovoltaic industry will be employed and developed. This method is based on the well known photoelastic principles, where the stress variations are measured based on the changes of light propagation velocity in birefringence material. In this research, the residual stress patterns that are not visible via conventional infrared transmission method will be used to locate defects. The magnitude of the residual stress fields associated with each defect is examined qualitatively and quantitatively. Firstly, the inspection of defects on wafer surface in early stage of wafer fabrication processes will be carried out. Next, an investigation of trapped particles and defects in bonded wafer with using the associated residual stress field will be also be covered.

Until now, it is known that stresses on the plane (y-z plane) perpendicular to the circumferential direction (x axis) of Oring exist and stresses on the plane (x-y plane and x-z plane) parallel to the circumferential direction of O-ring does not exist when O-ring is under uniform squeeze rate and internal pressure. But it was known that stresses of x-y plane and xz plane of O-ring under uniform squeeze and internal pressure were existed by this research. To analyze 3 dimensional stress distributions of O-ring under those loadings, stress distributions of every plane should be analyzed. Therefore, photoelastic experimental hybrid method for 3 dimensional stress distributions of O-ring under uniform squeeze and internal pressure were developed in this research. Photoelastic experimental procedures for 3 dimensional stress distributions of O-ring under those loadings were introduced. Stress distributions of O-ring under those loadings were analyzed by photoelastic experimental hybrid method developed in this research. Von Mises equivalent stresses at arbitrary point of O-ring under those loadings were analyzed.

Assembly stresses developed in a chain plate assembly play a critical role in the fatigue performance of the industrial chain. However, it is difficult to identify precisely the stress concentration zones and estimate its values using conventional industry-friendly tools such as the routine quality control test, pull out force test and numerical computations. In this context, reflection photoelasticity proves to be an excellent industry-friendly tool. Use of reflection photoelasticity technique has made it possible not only to instantly identify the stress concentration zones but also to quantify the stress and strain at any point on the chain plate.

Digital photoelastic evaluation of stress intensity factors (SIFs) of bimaterial interface cracks using the method of least squares and the multi-parameter stress field equations is of current interest. For this, positional coordinates (with crack tip as origin) and corresponding fringe orders of data points are collected along isochromatic fringe contours in such a way that the geometric features of the fringe field are captured. Whole-field evaluation of isochromatic parameter is now made possible by various techniques of digital photoelasticity, enabling automation of the data collection procedure and collection of data points along fractional fringe orders as well. However, the identification of the crack tip, still done interactively, is prone to error. When the crack tip location is inaccurately identified, the evaluated SIFs are considerably different. The effect of error in precise identification of the crack tip on the evaluated SIFs is analyzed with the help of theoretically simulated fringe fields, in order to arrive at a technique by which the crack tip could be detected in a semiautomated fashion reducing this error in the evaluated SIFs.

This paper presents some of our recent work on high-resolution, real-time 3D profilometry using a digital fringe projection method. In particular, we utilize the unique projection mechanism of a single-chip digital-light-processing (DLP) projector: sequential channel-by-channel switching. Three phase-shifted fringe patterns are encoded into the three primary color channels and switched naturally. A high-speed charge-coupled device (CCD) camera, synchronized with the projector, is used to capture each individual color channel of the projector. Because color is not desirable, the color filters of the projector are removed, and an external trigger signal is supplied to enable its projection. Since three fringe images are sufficient to reconstruction one shape, this technique can, theoretically, reach the refresh rate of a projector (typically 120 Hz). However, due to the speed limit of the camera used, the data acquisition speed is up to 180 fps, thus the 3D shape measurement speed can be as high as 60 fps, as it requires three images to recover one 3D shape. To reach simultaneous 3D data acquisition, reconstruction, and display, we developed various efficient algorithms, and used advanced graphics hardware techniques to boost the processing. In this paper, we will summarize the technologies we developed, and will present some of the research results.

High-speed and accurate shape measurement method is required in many industrial areas. We proposed a shape measurement method using pixel-by-pixel calibration tables produced with multiple reference planes. In this method, all the relationships between the phase of the projected grating and the spatial coordinates can be obtained for each pixel. We call it "whole-space tabulation method". This method excludes a lens distortion and the intensity warping of the projected grating in measurement results theoretically. Tabulation makes high-speed measurement possible. A high-speed and accurate shape measurement system can be possible to develop easily using this method. Random noise occurring in an imaging device and optical setup, however, causes error in this method. In this paper, accuracy improvement methods and the effectiveness for shape measurement using the whole-space tabulation method are shown.

Structured light projection techniques are an important and popular approach for whole-field surface topography. Within this branch, projection moiré interferometry is our preferred optical metrology method. The use of liquid crystal display (LCD) projectors to produce structured light patterns has been proposed and used before in projection moiré. It allows fast and easy adaptation of the grid pitch and thus measurement sensitivity. In this paper we will show how using a second liquid crystal panel makes the projection moiré technique even more versatile and performant: The setup incorporates optical demodulation (OD) which in turn allows for accurate phase-shifting and the use of phase-shifting algorithms (PSAs). The Z-resolution is high and no filtering or interpolation is needed in X-Y by using the gray scale value variations through the phase-shifting and optical demodulation. Thus, we make optimal use of the camera pixel resolution and achieve an uncompromised measuring resolution. Furthermore, the setup is entirely digitally controlled, needs no physical interaction and avoids mechanically moving component. The low-cost setup, technique and theory will be covered in this talk. The resolution and other performance properties will be discussed and demonstrated. And to conclude, an application to achieve elasticity parameters of membranes will be shown. interferometry is our preferred optical metrology method. The use of liquid crystal display (LCD) projectors to produce structured light patterns has been proposed and used before in projection moiré. It allows fast and easy adaptation of the grid pitch and thus measurement sensitivity. In this paper we will show how using a second liquid crystal panel makes the projection moiré technique even more versatile and performant: The setup incorporates optical demodulation (OD) which in turn allows for accurate phase-shifting and the use of phase-shifting algorithms (PSAs). The Z-resolution is high and no filtering or interpolation is needed in X-Y by using the gray scale value variations through the phase-shifting and optical demodulation. Thus, we make optimal use of the camera pixel resolution and achieve an uncompromised measuring resolution. Furthermore, the setup is entirely digitally controlled, needs no physical interaction and avoids mechanically moving component. The low-cost setup, technique and theory will be covered in this talk. The resolution and other performance properties will be discussed and demonstrated. And to conclude, an application to achieve elasticity parameters of membranes will be shown.

The least-squares method can be utilized in the calibration procedure for fringe projection profilometry to make it easier and more flexible, since the geometric parameters of the system are not to be measured and the precise control of plane moving is not required as well. Furthermore, the system components can be arbitrarily arranged which brings much convenience to practical measurement. With a consideration of camera lens distortion, a modified least-squares phaseheight mapping description is proposed. In this method, camera lens distortion effect is involved into the mathematical description of the system for least-squares estimation to reduce the influence of lens distortion. Both simulation and experiment are demonstrated to show the feasibility and convenience of this modified least-squares phase-height mapping method.

Surface profile measurement by non-contact optical methods has been extensively studied because of its importance in mechanical component inspection, reverse engineering, and 3-D solid modeling applications. Grating projection method is often used for non-contact shape measurement. Whole-space tabulation method, a kind of grating projection method, is a technique of producing phase-coordinate tables pixel-by-pixel which relates phases of the projected grating to the spatial coordinates. This method excludes a lens distortion and intensity errors of the projected grating in measurement results theoretically. Tabulation makes short-time measurement possible. One major problem is overflow of the detector. As a result, the underexposed and/or overexposed areas on the imaging device, where the phase information cannot be obtained with high accuracy. We previously proposed an evaluation method for the reliability of the analyzed phase in a phase-shifting method using Fourier transform (PSM/FT) for shape measurement. This phase reliability evaluation value is useful to merge data when the measurement condition is changed. In this paper, it is confirmed that accurate shape measurement and the whole-space tabulation method using phase reliability evaluation value can be performed.

Flatness/Curvature measurement is critical in many Si-wafer based technologies ranging from micro-electronics to MEMS and to the current PV industry. As the thickness of the wafer becomes smaller there is an increased tendency for it to warp and this is not conducive to both patterning as well as dicing. Monitoring of curvature/flatness is thus necessary to ensure reliability of device and its uses. However, due to the prevalence of surface flatness measurement systems that flooded the market, the cycle time for curvature measurement system has become one of the critical factors for the user to consider. A simple and rapid whole-field curvature measurement system using a novel a computer aided phase shift reflection grating method has been developed and discussed in the previous publications. Laterals gratings in horizontal has vertical directions are needed in order to realize the curvature information on the wafer in both directions. In this paper, with same system setup, circular grating is being projected on to the specimen to measure the curvature distribution of the wafer. With the aid of coordinate-transform method and the digital phase-shifting technique, the digital images of reflected gratings are processed automatically and analyzed in the polar coordinate system. Unlike vertical or horizontal line gratings, the utilization of the circular gratings in radial shearing method provides curvature information in all directions, not only in one. Further, only four phase shifted images are captured and the measurement cycle time is thus reduced by half.

A new method to measure the spacing and direction in the ordered assembled nanoparticles by using the electron Moiré new method to measure the spacing and direction in the ordered assembled nanoparticles by using the electron Moiré fringes has been developed. In this method an assembled nanoparticle array can be consider as a model grid. When the electron beam was irradiated on the top of the nanoparticles, the amount of secondary electrons per primary electron is quite large. On the other hand, when the electron beam was irradiated on the valley among the neighboring nanoparticles, the amount of secondary electrons per primary electron is smaller. The difference of the generated secondary electrons per a primary electron fabricate periodical bright and dark pattern, which is the electron mesomoiré fringes. Using this method, the spacing and orientation of the assembled nanoparticle array was measured. new method to measure the spacing and direction in the ordered assembled nanoparticles by using the electron Moiré fringes has been developed. In this method an assembled nanoparticle array can be consider as a model grid. When the electron beam was irradiated on the top of the nanoparticles, the amount of secondary electrons per primary electron is quite large. On the other hand, when the electron beam was irradiated on the valley among the neighboring nanoparticles, the amount of secondary electrons per primary electron is smaller. The difference of the generated secondary electrons per a primary electron fabricate periodical bright and dark pattern, which is the electron mesomoiré fringes. Using this method, the spacing and orientation of the assembled nanoparticle array was measured. fringes has been developed. In this method an assembled nanoparticle array can be consider as a model grid. When the electron beam was irradiated on the top of the nanoparticles, the amount of secondary electrons per primary electron is quite large. On the other hand, when the electron beam was irradiated on the valley among the neighboring nanoparticles, the amount of secondary electrons per primary electron is smaller. The difference of the generated secondary electrons per a primary electron fabricate periodical bright and dark pattern, which is the electron mesomoiré fringes. Using this method, the spacing and orientation of the assembled nanoparticle array was measured.

Multipoint Diffraction Strain Sensor (MDSS) is a novel and promising strain sensing system to acquire whole field strain information with high accuracy without the need for numerical differentiation. Compared to traditional optical diffraction strain sensors, the main advantage of MDSS is the use of micro-lens array to get whole field information. Both tilt and in-plane strain can be acquired separately by using two symmetric incident laser beams. However, it is costly and troublesome to fabricate, adjust or replace lens arrays for different applications. A practical way to solve this problem is to use a liquid crystal lens as spatial light modulator which displays Diffractive Optical Element (DOE) based lens array. This liquid crystal lens is software controlled capable to display any user designed DOE pattern. The sensitivity and field of interrogation is thus tuneable by changing focal length of lens arrays. Moreover arbitrary size or shape of lens arrays can be designed to measure certain part of the specimen in most interest. Experimental results with different lens arrays are demonstrated for uniform rotations.

The multi-scale deformation behavior of multi-layered steel during tensile loading was investigated by in-situ FE-SEM observation coupled with multi-scale pattern. The material used was multi-layered steel sheet consisting of martensitic and austenitic stainless steel layers. Prior to in-situ tensile testing, the multi-scale pattern combined with a grid and random dots were fabricated by electron beam lithography on the polished surface in the area of 1 mm² to facilitate direct observation of multi-scale deformation. Both of the grids with pitches of 10 μm and a random speckle pattern ranging from 200 nm to a few μm sizes were drawn onto the specimen surface at same location. The electron moiré method was applied to measure the strain distribution in the deformed specimens at a millimeter scale and digital images correlation method was applied to measure the in-plane deformation and strain distribution at a micron meter scale acquired before and after at various increments of straining. The results showed that the plastic deformation in the austenitic stainless steel layer was larger than the martensitic steel layer at millimeter scale. However, heterogeneous intrinsic grain-scale plastic deformation was clearly observed and it increased with increasing the plastic deformation.

The nondestructive instrument as the application of coupling phenomenon between the thermal wave by non-Fourier heat conduction and the thermal stress wave by elastic vibration has been proposed for more than twenty years. This technique is called scanning electron-induced acoustic microscope (SEAM). Our own-built SEAM has, so far, successfully provided some nondestructive observations of micro-defects such as the micro-voids of sintered materials, martensitic phase transformation, grain boundary without any chemical etching, and so on. Some defects of them were indeed confirmed by digging using focused-ion beam (FIB) fabrication to make certain of those beings. In order to fully understand this coupling phenomenon, this paper gives the simple one-dimensional computational model of the multiphysics to explore the detailed transportation mechanism. The cyclic chopping of electron beam with extremely high frequency yields the thermal wave according to non-Fourier heat conduction, which respects the thermal relaxation different from the ordinal diffusive heat transmission. The wavelength of the thermal wave, which may determine the essential SEAM resolution, decreases as increasing the thermal relaxation time of material and also the modulation frequency. The numerical summaries are qualitatively in agreement with some nondestructive observations with changing the blanking frequency.

The comparative study on the image quality between Computed Radiography (CR) and digitized film radiograph has been carried out. We have successfully digitized a radiographic film of an aluminum step wedge, an ASTM and coins using a flatbed scanner. Then, a comparative study was developed using CR as a reference. We used 4 set-up variations of kV and mA. The image quality was assessed based on the visual analysis: brightness, sharpness, and contrast, and the physical information analysis. The results show that visually the image quality of CR was better to the digitized film radiographs. However, CR was unable to distinguish the physical information such as the effect of voltage or current and the object characteristic to the image quality.

Ultra-sonic is one of the major methods to inspect and locate the damage or flaws of materials in the components or structures in engineering¹. The technique to inspect the crack initiation in mid-plane by ultrasonic in real time is presented and developed upon the requirement of detecting the initiation of cracks for thick compact tension specimen (CTS) to set up the I-II mixed mode fracture criterion. The paper is concerned with the application of an ultra-sonic scheme to detect initiation or growth of through-thickness crack at mid-plane from the surface during the loading. The technique in relation to the inspection of crack initiation in mid-plane by ultra-sonic is described in detail. The principles of the technique, and the equipment required to facilitate it are reviewed. The verification of the technique which is supported by a specific example of a CTS inspection performed on an I-II mixed mode fracture test shows that the method is valid and the technique can be capable of detecting delaminations, disbonds and lack-of-adhesion in a wide diversity of coated and uncoated materials. It is also capable of assessing the quality of composites.

Fatigue failure of steel occurs when small cracks form in a component and then continue to grow to a size large enough to cause failure. In order to understand the strength of steel components it is important to find the cracks which eventually grow to cause failures. However, at present, it is not easy to distinguish, in the early stages of growth, the cracks which will grow fast and cause failure. We hypothesized that it may be possible to distinguish them by comparing changes in the magnetic flux density around the tips of those cracks that grew large enough to cause failure. In order to measure these changes in magnetic flux density, we developed a scanning Hall probe microscope and observed the fatigue cracks growing from artificial slits in carbon tool steels (JIS SKS93). We also compared the changes in magnetic flux density around crack tips which grew under different loads and found that there is a strong correlation between the magnetic flux density, crack growth and stress intensity factors. In order to understand this relation, we measured the changes in the magnetic flux density and residual tensile stress by using an X-ray system, and found that the magnetic flux density changes not only in the plastic deformation area but also in the area of elastic stress field with increased stress.

Distillation columns are considered as one of the most critical components in oil and gas plants. The plant performance depends on the ability of these columns to function as intended. Defective columns may lead to serious consequences to the plant operation, and hence the quality of product. In order to perform any inspection techniques to distillation column for NDT practitioner, the best facility was designed when the adjustable defeats of distillation column test rig has been developed. The paper discussed the development and the function of this facility.

Due to the threat of impact to spacecraft from space debris and meteoroid, space debris and meteoroid shields have been raised and used in many spacecrafts. In order to conduct an assessment of spacecraft module-wall damage impacted by debris cloud created by space debris and meteoroid high-velocity impact on the shields, it's necessary to develop a location method for the debris cloud impact. The method based on virtual wave front for acoustic emission source location has been investigated and extended to locate the impact position of the debris cloud. Debris cloud hypervelocity impact experiments were conducted by using a two-stage light gas gun, the experimental results indicate that: The signals induced by debris cloud contain a0, s0, s2 mode wave, the virtual wave front location method can be extended to locate the impact position of the debris cloud effectively, the AE signals contain more high frequency components than AE signals created by single projectile impact event. The results provide a reference for the development of the sensor systems to detect impacts on spacecraft.

Fatigue failure of steel occurs when small cracks form in a component and then continue to grow to a size large enough to cause failure. In order to understand the strength of steel components it is important to find these cracks. However, at present, it is not easy to distinguish the cracks that will grow fast and cause failure. We developed a three-dimensional scanning Hall probe microscope (3D-SHPM) and observed fatigue cracks at room temperature while they were growing. Four-point-bending fatigue tests were carried out using pre-cracked specimens (JIS-SUJ2, bearing steel). We observed the two-dimensional magnetic flux density distributions around the crack tips and found that there is a strong correlation between the changes in the magnetic flux densities and the crack growth. In order to understand this, we looked into all the three components of the magnetic flux densities, and found that they shape an arched bridge around a crack. We also found that the magnetic flux density moves in front of the crack tip along the crack growth direction.

The metal honeycomb material has high strength and high stiffness, as a high-performance sandwich panel, it is an ideal lightweight structural material, and widely used in aviation, aerospace, shipbuilding and other fields. In this paper, the improved SHPB instrument is used for testing the in-plane and out-plane mechanical properties of the steel honeycomb panel three-point bending specimen, and also compare the results with the static in-plane and out-plane three-point bending experiments results which is tested by the INSTRON 4505 electronic universal testing machine, and then study the mechanical properties of the steel honeycomb panel three-point bending specimen under transverse dynamic impact load. From the results it can be see that, for the out-plane three point bending experiment, L direction mechanical properties is better than the W direction, and the honeycomb core play an important role during the specimen deformation, while for the in-plane three point bending experiment, the honeycomb core mechanical role is not distinctness.

Square and circular tubes are generally used as a main frame for vehicle structures, since they are considered as high efficiency energy absorption elements. Therefore, various techniques to increase the energy absorption with less mass increment have been studied for years. One of those techniques is by filling foam in the tube. This paper is aimed to investigate the behavior of foam-filled square and circular tubes under axial load. The study was carried out experimentally by using a number of square and circular steel tubes having various geometries. Each tube was filled with polyurethane foam. The density of foam was varied from 100, 200 and 300 kg/m³. The foam-filled tubes were crushed axially using a 1,000 kN universal testing machine. The crush speed was 50 mm/min. The load-displacement were recorded and the energy absorption of each specimen was calculated and compared. In this paper the specific energy absorption is used as a key indicator, rather than energy absorption, in order to take the mass increment into account. The result revealed that the energy absorption of tube is increased as the density of foam increases. However, the specific energy absorption is not increased in many cases. In addition the collapse modes of the specimens were also discussed.

A strain rate calculation formula of split Hopkinson pressure bar (SHPB) test is derived from one-dimensional stress wave propagation theory. According to the test conditions and specimen size, the test strain rate can be calculated by the formula; and the strain rate limitative range of SHPB test is analyzed. 2D numerical simulation SHPB test of a bilinear strain-hardening material was carried out by LS-DYNA, and a series of SHPB tests of AA7055 aluminum alloy at different strain rates were designed by this strain rate calculation formula. The results indicate that this strain rate calculation formula is accurate and reliable, and the formula has some directing significance for SHPB testing program design.

Ping-pong balls were employed to experimentally study the deformation and buckling behaviors of thin-walled spherical shells compressed onto a rigid plate. First, the quasi-static tests were conducted on an MTS tester, in which the ball was compressed onto a PMMA plate. The compression force and displacement of the crosshead were obtained by the MTS, while the evolution of the contact zone between the ball and the plate was recorded by a digital camera. Two transition points were identified from the load-displacement curve and a snap-through buckling gradually happened after the contact zone reaches a critical size. By correlating the evolution in the contact zone and the load-displacement curve, it is found that the two transition points are corresponding to the traveling of the plastic hinges around the contact zone and the unrecoverable buckling, respectively. In dynamic tests, the ping pong ball accelerated by an air-gun impacted onto a PMMA plate with the velocity ranging 10-50m/s, whilst the dynamic deformation process of the contact zone was captured by a high-speed digital camera. As a result, the impact duration, the maximum contact diameter, and the contact diameter at buckling under different impact velocities were obtained. It is revealed that when contact diameter is the same the energy absorbed by the ping-pong ball is much larger than that in quasi-static tests.

On the basis of three point bending dynamic fracture tests with high speed photography, the fracture surfaces are scanned by Scanning Electronic Microscope(SEM)and Laser Profilometer. Instability in rapid rupture of rocks is analyzed from the phenomena that occur in those meso-structures. From energy point of view, the instability mechanism concerning microbranching and fracture mode dependence of crack velocity is discussed. As a result of instability, the critical dynamic fracture energy is an increasing function of crack velocity, rather than a constant material parameter.

The ARMOR TPS is one of important candidate structure of RLV. It will be the best selection for all kinds of RLV. So the ARMOR thermal protection system will be used in aviation and spaceflight field more and more widely. ARMOR TPS panel is above the whole ARMOR TPS, and the metal honeycomb sandwich structure is the surface of the ARMOR TPS panel. So the metal honeycomb sandwich structure plays an important role in the ARMOR TPS, while it bears the flight dynamic pressure and stands against the flight dynamic calefaction and impact load. The metal honeycomb sandwich structure is made of upper faceplate, lower faceplate and honeycomb core. In the course of the reusable launch vehicle working, it is possible that the space chips impact its outer surface. The main problem is what impact the metal honeycomb sandwich structure can stand and how many times it can stand. In the high speed impact experiment we choose different quality and velocity to simulate real space environment. This paper will analyze the mechanics behaviour of metal honeycomb sandwich structure in the course of impact, and then we make sure the limit impact load and get the effect of impact flaw.

The free falling motions of thin circular disks in still water were investigated experimentally. All six degrees of freedom of a falling disk were determined by a stereoscopic vision method. For the disk of small dimensionless moment of inertia (I* < 6.0 × 10^-3), three types of motions were identified, including a planar zigzag one and two newly discoveried motions. The two new motion both have non-planar trajectory and continous rotation about the disk's symmetry axis. Flow visualizations were also carried out to show the wake structures with different types of motions.

In this paper, a test based on the wavelet transform for instantaneous three dimensional (3D) Carp tail fin profile measurements and analysis the kinematics of Carp tail fin method was proposed to understand the function of the tail fin. This experiment method is used in cruising carp. Projecting a moiré fringes onto a tail fin, the deformed fringe pattern containing 3D information was produced and varied with the movement of tail fin. The time-sequence deformed fringe pattern images were captured by a high speed camera. By wavelet transform profilometry, the tail fin movements were really reconstructed. On this basis, the kinematics parameter of tail fin was analyses. Experimental results indicate that the 3D profile of tail fin was varied during the tail-beat cycle. Analysis of tail kinematics suggests that, at a swimming speed 0.5Ls^-1, the tail beat frequency is 1.42Hz and the dorsal lobe of the tail undergoes a 15.6% greater lateral excursion than does the ventral lobe. The timing of maximal lateral excursion was different at different location of tail fin.

Ceramic foams are recently used in many applications such as porous burner, support catalyst, heat exchanger, etc. In the area of porous media applications, pressure drop is considered as a very significant parameter. Especially, in cases of hot fluid with high velocity, this is counted as a very important factor. In this research, pressure drop was studied in different porous media made of SiC and Al2O₃.The effect of hot and cold fluid on the pressure drop was extensively studied. As a result, it was concluded that the fluid velocity has a very remarkable effect on the pressure drop. Moreover, the effect of viscosity on pressure drop was investigated. Accordingly, it was realized that increasing the temperature causes an increase in the viscosity and a decrease in gas density. These all lead to a descending trend for pressure drop. Eventually, it was understood that for foams with finer pores, the pressure drop will have a slow descending rate. This is due to high impact of viscosity on pressure drop in finer foams.

Some experiments involving the removal of particles from a hole in a (solid) plate are presented in this work. The particles are removed using oscillating bubbles, which are generated with an electric spark. The plate and the bubble are submerged in water. At least one side of the plate is surrounded by water as well. In some cases, one side of the plate (the side that is not exposed to the bubble) is exposed to air (air-backed plate). The experimental technique to generate oscillating bubble is briefly described. A relative simple low voltage system is used here, by short-circuiting a charged capacitor under water. The results show that it is indeed possible to remove particles from holes using this technique. Some typical examples will be given in this article, together with a brief explanation of the physics involved, which are different for water-backed and air-backed plates.

Ceramic foams are new class of materials that employ as medium of porous burners. In this study, pressure drop through foams was investigated. An experimental set up was made to measure pressure drop through the ceramic foams. Nine types of various Alumina and Silicon carbide foams has been investigated. In order to examine the effect of temperature increase on pressure drop a heater has been employed. A model was presented for measurement of hydraulic pore diameter. A dimensional analysis was carried out and a new formula based on it has been offered. The offered correlation have different coefficients for Alumina and Silicon carbide foams.

Investigations of the flow behavior are currently carried out experimentally on models of hydraulic turbines. Quantities such as unsteady velocity can be acquired using PIV or LDV techniques, static wall pressure using steady or unsteady pressure transducers and wall shear stress using hot-film anemometry. More rarely acquired however, the unsteady total pressure at different locations in the flowstream would give more information on the flow dynamics and would be a key component for setting boundary conditions for CFD simulations. Following the example of classical Pitot tubes, which can only give averaged pressure values though, we have developed a five-hole pressure probe with embedded sensors that can measure unsteady values of total pressure, local flow velocity and direction. The probe head is designed to have a minimum impact on the flowstream, and the miniature sensors are placed in a cross configuration compared to the probe's support axis. This paper focuses on the utilization of normalized calibration coefficients and their use for unsteady values, and on the justification for using our cross sensor repartition. The calibration setup is presented briefly, including a water potential jet that requires the calculation of specific calibration coefficients. Different phenomena were observed during experimentation. Their impact on the accuracy of the probe is analyzed. The probe's operation range for this particular calibration setup is discussed. Finally, we focus on the influence of the sensors repartition on the tridimensional shape of the calibration coefficients, and we provide a way to calculate the first approximate solution for the reverse calculus while the sensors are not aligned with the probe's arm.

In this study, the pulse combustion is used to produce nanometer-size particle and the mechanism is clarified. The feature of jet generated by the pulse combustion chamber, whose pulse cycle is about 600 Hz, is visualized by the shadowgraph technique and is compared with that by the burner combustion. There exists very fine structure of vortices in the jet of pulse combustion. The water drop whose diameter is about 3mm is broken-up in this jet. This breakup does not occur in the jet of burner combustion. The droplets generated by the breakup are evaporated instantly and the nanometer-size particle is produced. Sound level in the jet is about 140 dB and sound power is not strong enough to promote the evaporation. Instead of sound, the very fine vortices, whose scale is of some mm, play an important role. These vortices give pressure fluctuation on the water droplet of 5000 Hz to 8000 Hz and they promote evaporation and deformation of the droplet.

In the present study, the effects of rotating a circular cylinder on the vortex shedding are investigated by Particle Image Velocimetry measurement. The experiments were conducted for flow past a circular cylinder of aspect ratio 25 in a recirculating water channel at Reynolds numbers in the range of 200 to 1000. The rotational to translational speed ratio α varies from 0 to 5. The present results show the existence of a critical α value in the range of 2 to 3, above which the vortex shedding is suppressed as reported in the literature. The critical α appears to decrease with increase in flow Reynolds number. Below this critical α, the Kármán vortex street is observed. When α increases, both flow separation positions move in the direction of cylinder rotation; and vortex shedding is increasingly deflected towards the rotation direction of the cylinder. Above the critical α, vortex shedding disappears, and a closed streamline is formed around the cylinder. At higher α, only counter clockwise (same direction as cylinder rotation) vorticity was observed around the cylinder. Through this investigation, it is hoped that we can better understand the effects of cylinder rotation on the flow past a slender circular cylinder.

A blower using the thermal edge flow was proposed, which consists of thin plates in which there are several cuts and the one side of each cut is rounded, and one-way flow is realized. This blower was shown to promote the freeze-drying process in a low-pressure environment. Using a freeze-drying equipment which has a cold trap and heating plate that supplies the latent heat to materials, several sponge blocks and chemical powder were frozen and dried, and the drying time was shortened to almost a half by this blower.

From past research, it is known that even for a very slender cylinder with aspect ratio of several hundreds, the flow remains two-dimensional only at low Reynolds number, and will become three-dimensional once a certain critical Reynolds number is exceeded. Most of the works reported are for circular and square cylinders. The present work is intended to look into wake transition phenomena that take place in the wake of two different trapezoidal and one triangular cylinders. With the experiment set up in a water tunnel, the frequency of vortices shed from trapezoidal and triangular cylinders was carefully measured using hot film anemometry. Experimental data revealed that the discontinuities in the S-Re relation, similar to those observed for circular and square cylinders and which mark the transition of the wake to Mode A and Mode B instabilities, are also present in flow past trapezoidal and triangular cylinders. However, the Reynolds numbers at which the discontinuities take place are cross-sectional geometry dependent. For Trapezoidal Cylinder 1 and 2 with a rear face 75% and 50% the length of the front face, respectively, the two discontinuities in the S-Re relation take place at Re = 152 & 173 and 143 & 176, respectively. For the Triangular Cylinder with apex pointing downstream, the first discontinuity occurs at Re = 164. Some preliminary flow visualization was also carried out to confirm the existence of the streamwise vortices associated with Mode A and B instabilities.

The mixing dynamics of granular materials immersed in a liquid was experimentally studied in a quasi-2D rotating drum. A DV (SONY DCR-TRV900 NTSC) motion corder analyzer was used to record the motions of granular materials. The effects of interstitial fluid viscosity and filling degree on the mixing index, mixing rate constant, and dynamic repose angle in the rotating drum were investigated and discussed in this paper. The experimental results show that the interstitial fluid viscosity has almost not influence on the final stable mixing index but has significantly effects on the mixing rate constant and dynamic repose angle in slurry granular flows. The results show that the mixing rate and dynamic repose angle increase with increasing the interstitial fluid viscosity. The results also indicate that the filling degree plays an important role in mixing dynamics in slurry granular flows. The mixing rate constant is demonstrated to be decreased with increasing the filling degree. The dynamic repose angle is not altered by the filling degree. Finally, we find that the dynamic repose angle and the mixing rate constant increase slightly at high Stokes number and increase dramatically at low Stokes number with decreasing Stokes number.

This paper investigates the effects of nanoparticles on surface tension and equilibrium contact angle of TiO₂ - DI water nanofluids. Experimental measurements of surface tension by using the pendant droplet method show that the surface tension of the TiO₂ - DI water nanofluids depends weakly on nanoparticle concentration; however, at higher nanoparticle concentrations the surface tension is lower. Various mechanisms are reported to explain this behavior. Experimental measurements of contact angles of the TiO₂ - DI water nanofluids droplets on borosilicate glass slides exhibit strong nanoparticle dependence, and the general trend is increment of the contact angles with nanoparticle concentration. The effect from the so-called disjoining pressure due to the presence of nanoparticles within the thin nanofluid film wedge at the vicinity of the three-phase contact line is examined. However, the phenomenon is attributed to the pinning of contact line and local changes in solid-liquid interfacial tension due to the depositing of nanoparticles on adsorption sites on solid surface.

This paper presents the results of a laboratory study of evaluating the fatigue characteristics of granite asphalt mixtures (GAM) using different testing methods. In the study, the fatigue performances of GAM were evaluated with Superpave indirect tensile test (IDT) and four-point beam fatigue test. Specimens were conditioned by four different methods: (1) one cycle of freeze-thaw (F-T), (2) two cycles of F-T, (3) immersion in 60°C water bath for 30min (4) immersion in 60°C water bath for 48h, and contrastive analysis was made with unconditioned specimens. Investigation of moisture damage influence on the fatigue properties of GAM with and without Hydrated Lime (HL) was done. The results from this study indicated that both Superpave IDT and four-point beam fatigue test agreed with each other in ranking the fatigue property of GAM. Increasing F-T cycles or immersion time would decrease fatigue life in GAM, and the addition of HL was effective to prolong the fatigue life in GAM.

Nanoparticle imaging using evanescent illumination is a very useful technique for elucidating physical phenomena near the walls of microchannels in microfluidic systems. Since the intensity of evanescent illumination decays exponentially with distance from the wall surface, particles closer to the wall appear brighter than those further from the wall. This enables the three-dimensional positions of nanoparticles in near-wall regions to be measured. In this study, the behavior of nanoparticles in a microfluid was observed experimentally. 20-nm-diameter fluorescent nanoparticles were employed rather than biological molecules for single-particle imaging. To overcome the poor measurement accuracy due to the small diameter of the nanoparticles used for imaging and the low fluorescence intensity of a single nanoparticle far from the wall, the image settings were optimized and a novel image processing algorithm was proposed. The experimental results reveal that the nanoparticle concentration varies in the direction normal to the wall. The nanoparticle concentration decreased with proximity to the wall surface; in particular, the concentration in the region from 0 to 170 nm, was much lower than that in more distant regions from the wall. Moreover, the nanoparticle concentration in the near-wall region decreased as the diffusion coefficient of the nanoparticles decreased.

In this paper, dynamic imaging of micro-particles in 3D using lensless in-line digital holographic microscopy (LIDHM) is explored. The methodology presented retains the reconstructed pixels size used for the particles analysis at different depth locations under converging wave reconstruction geometry. Experiments studying the 3D visualization of copolymer microsphere suspensions in distilled water are presented. The dynamic behavior of microspheres in 1mm cube volume is captured and the numerical reconstruction provides their volumetric flow behavior. From the plot the 3D visualization and the location of each particle, its depth and dynamic behavior can be observed clearly. The proposed work is useful for tracking the 3D dynamic behavior of particles and can be used to predict the motion of the moving particles in volume.

In order to improve the performance of hydrodynamic journal bearings, the effect of bearing profiles had been investigated using a new approach for shape optimization of hydrodynamic journal bearings based on a profile parameterization method. The optimization process was carried out using Fourier series to describe the bearing profile. The load capacity increases with the increasing order of Fourier series. However the optimized result was almost fully achieved at the Fourier series of order 2. In this paper, three kinds of optimized shapes at the order of the general film thickness equation of 1, 2 and 3 were manufactured and taken as experimental objects respectively. Experimental apparatus was described and some experimental data was presented. The comparison was made for the optimized bearings between numeric values and experimental data. The results show that the new method for shape optimization of hydrodynamic journal bearings based on the general film thickness equation is feasible.

A finite element method and reflection photoelastic techniques are presented to determine the KI stress intensity factor of cracks with hard inclusion and several crack length per width for two-dimensional fracture mechanics problems. The paper starts from describing two-dimensional fracture mechanics theory and finite element formulation using the quadrilateral and triangular finite elements. The computational procedure and related finite element equations are explained. The reflection photoelastic theory and its experimental procedure with the use of the stress optic laws are then described. Performance of both techniques is evaluated by analyzing a single edge cracked plate made from polycarbonate. A plate with a hard inclusion is studied. The hard inclusion is made from aluminum. The KI stress intensity factor is found to be a function of the crack length per width. The both results are evaluated with Brown. This example demonstrates the efficiency of the finite element method to provide accurate solutions as compared to those from the reflection photoelastic technique.

Full scale wind turbine experiment was held in Colobraro, Italy. Based on the data collected in the observation station wind tunnel experiment was carried out in Galleria del Vendo Del Politecnico di Milano(GVPM). The full-scale experiment can be used as validation of numerical simulation. However, because of the practical difficulties such as, selection of suitable sites and expensive cost, wind tunnel experiment and numerical simulation were considered as more commercial ways to predict wind flow over hilly terrain. Both wind tunnel test and numerical simulation were made at three sites, where wind turbines were erected. And the wind turbine model was made to scale of 1:50. The wind tunnel model was test with two typical approach wind direction 180 degree and 240 degree. It was observed that the wind speed up depends on the approaching wind direction. And numerical simulation was done in these two typical approach wind direction. Numerical simulation results give the best agreement with respect to the wind profile. Therefore numerical model is suitable for prediction of wind flow over hilly terrain.

Creation of strong clamping or gripping becomes a crucial issue in micro and nano scale mechanical experiments. In this paper, several kinds of clamping in micro/nano scale experiments are investigated and compared. Topics include the clamping based on the electron-beam-induced deposition (EBID), the van der Waals interaction, the capillary force, and the electrostatic attractive interaction. The clamping strength and mechanism are analyzed both theoretically and experimentally. The influence of the relative humidity on the micro/nano scale clamping is discussed. The clamping strengths and performances of different clamping methods are also compared considering the size and the material of the clamped objects, and the application environments.

The Atomic Force Microscope (AFM) is a powerful tool in the fields of micro- and nano-metrology for the measurement of surfaces with micro-/nano-structures. However, there are some limitations to the vertical measuring range when the step size of a micro-/nano-structure is bigger than the tip height. The tip height, typically 15 μm, is defined as the distance from the apex of the tip to the bottom surface of the cantilever. To avoid possible interference between the cantilever and the structures under test, the maximum measuring range is usually set at one-third of the tip height to prevent any damages on the tip/cantilever and the test surface. In addition, the vertical measuring range in a conventional AFM is also limited by its available vertical scanning range, typically less than 10 μm. As such, a structure with a height or depth of several tens of micrometres cannot be measured by a conventional AFM. To overcome these limitations, a longer tip and larger vertical scanning range in AFM are needed. In this paper, a newly developed long diamond tip up to 65 μm is mounted on a tipless AFM cantilever and used with a Large Range Metrological AFM (LRM-AFM) which has a vertical scanning range of up to 5 mm with a resolution of 0.1 nm in order to measure structures with deeper groove. Measurements were successfully made on a step height of 24 μm, and the result obtained is very promising and this can effectively extend the vertical measuring range in nano-scale dimensional calibrations and measurements.

Porous silicon (PS) film was widely used in micro-systems sensors duo to its special properties. Nevertheless, intrinsic and processing residual stresses always introduced into porous silicon, always inducing the collapses and cracks inside the film and on the interface when the PS structure in service and/or during manufacture and storage. This paper presents a systematic study on the Raman stress measurement of porous silicon. Firstly, a theoretical model on the analytic relationship between stress and Raman-shift is presented by analyzing the micro-structures and transversely isotropy property of forest-like porous silicon film prepared on Si wafer by electrochemical etching. Meanwhile, the nano-indentation and digital Speckle correlations is utilized to determined the Young's moduli and Poisson's ratios of the PS samples, respectively. Based on the theoretical model and material parameters above, the coefficients in the Raman to stress relationship of porous silicon are achieved. By applying Micro-Raman spectroscopy, the distribution of intrinsic residual stress along the depth of PS-film/Si-substrate structure is measured. Then, a dynamical capillarity experiment is preformed to analyze the real-time stress transformation during PS drying, and the failure mechanisms by capillarity are discussed.

In microbiochemical analysis, the concentration of biomaterials near a wall greatly affects the detection and reaction efficiency. In this paper, we evaluate the interaction between nanoparticles and a microchannel wall. We measured the concentration distribution of 100-nm-diameter particles, which are equivalent in size to viruses, and attempted to cause nanoparticles to accumulate near the wall by applying an electric field with the aim of improving the reaction efficiency. We used total internal reflection fluorescence microscopy to measure the 3D particle distribution. This technique employs evanescent light (the intensity of which decays exponentially with distance) as illumination. By exploiting the characteristics of evanescent light, we were able to determine the 3D-position of a particle from its luminescence. The results reveal that there are very low concentrations of particles near a channel wall due to the potential barrier between the particles and the wall. This implies that immune reactions will not occur effectively near walls. Subsequently, we tried to concentrate nanoparticles near the wall by applying an electric field to the suspension. The particles moved toward the wall and became attached to it, overcoming the potential barrier. We anticipate that applying this method to biochemical analysis will greatly increase reaction efficiencies.

The Shape memory alloys (SMAs) wires have been used for medical and engineering filed due to the shape memory effect and the superelasticity effect. It is necessary to measure the mechanical properties of the SMA wires accurately. In this paper the mechanical properties of the shape memory alloy wires with different diameters were studied by a self-made testing system. A loading apparatus driven by step motor was used to apply load, and a load cell with the accuracy of 10 mN and the capacity of 90N was used to measure the value of the load. An optical extensometer based on the mark shearing method was used to measure the strain of the SMA wires, which had accuracy with 5 micron-strains in strain measurement. The mechanical properties of the shape memory alloy wires were studied. The nominal stress-strain curves of the SMA wires were acquired. The superelasticity effect was also studied. The successful experimental results also demonstrated the feasibility of the system in silk-like specimen measurement.

Moving micro-mechanical structures combined with laser light sources and micro-optics enable a number of powerful applications in display, imaging, and spectroscopy. Examples of systems developed in our laboratory are: rotational scanners developed for micro-projectors, dynamic diffraction gratings with large out-of-plane motion developed for Fourier Transform spectrometers, and 2 degree-of-freedom MEMS stages that carry micro-lens arrays for laser beam steering and imaging applications. Precise control of motion is critical in all those applications. We developed a number of optical characterization tools for point-based and fullfield dynamic characterization of micro and nano mechanical structures. In this paper, we first briefly discuss the applications and then describe the details of the optical characterization tools. First setup is a stroboscopic interferometry for dynamic deformation analysis. Second setup is a simple technique for simultaneous in-plane and out-of-plane measurement with nanometric precision. The setup is constructed using one photo detector and a Mirau-type interference objective. For out-of-plane measurements, interference fringes are used to compute the the deflection amount. For in-plane measurements, knife edge technique is used to modulate the reflected beam intensity using a sharp edge in the object. Third setup is a simple optical angle sensor for rotational mirrors, which uses only one bi-cell photo detector. The setup is able to measure amplitude, phase, and quality factor of torsional devices.

In microindentation testing, an indentation size is smaller than the average grain size of industrial polycrystalline metals, so that the indentation shape is affected by the crystallographic orientation of grain on which the indentation is imposed. Hence, clarification of the relation between the crystal orientation and the indentation shape leads to the possibility of estimating the crystal orientation by microindentation testing. In the present study, influences of crystal orientations upon indentation shapes on grains of polycrystalline titanium were investigated. The crystal orientations of grains were measured by an electron backscattered diffraction method, and indentation tests with a triangular pyramidal indenter were performed on the grains. The indentation shapes were thus observed by a laser-scanning microscope and an optical microscope. The results revealed that the direction of the most bulged position of edges from the apex of triangular indentation agreed well with an a-axis direction. It was also found that deviation of the indentation edge from the ideal one became smaller with larger angle of inclination of c-axis for the sample surface, owing to the limited slip direction of titanium. Those results suggest the possibility to evaluate the crystal orientation of titanium grain directly from the observed indentation geometry.

Fabrication of micro devices by using micro metal forming was proposed by the authors. We developed a desktop servo-press machine with precise tooling system. Precise press forming processes including micro forging and micro joining has been carried out in a progressive die. In this study, micro metallic valve and pump were fabricated by using the precise press forming. The components are made of sheet metals, and assembled in to a unit in the progressive die. A micro check-valve with a diameter of 3mm and a length of 3.2mm was fabricated, and the property of flow resistance was evaluated. The results show that the check valve has high property of leakage proof. Since the valve is a unit parts with dimensions of several millimeters, it has advantage to be adapted to various pump design. Here, two kinds of micro pumps with the check-valves were fabricated. One is diaphragm pump actuated by vibration of the diaphragm, and another is tube-shaped pump actuated by resonation. The flow quantities of the pumps were evaluated and the results show that both of the pumps have high pumping performance.

A micro-sized 2-DOF grating laser scanner which is made to vibrate in-plane by an electrical comb-driven circular resonator drive is fabricated and tested. The frequency response of the prototype scanner in atmosphere to different driving voltages and the variations of its natural frequency with scanning amplitude are measured. The results are compared with those from finite element simulations using a comprehensive dynamic model, including the effects of geometric nonlinearity of the flexural beams under large deformations. The comparison shows that the predictions made by the developed nonlinear model are generally valid.

In our previous studies, we found that heat treatment after coating with TiN could be an effective method to improve the mechanical properties of TiN-coated steel. However, it was not clear whether a similar effect could be obtained for other types of ceramic thin films. The heating temperature condition suitable for improvements of various thin films also has not yet been revealed. In this study, for three kinds of ceramic thin films, TiN, TiAlN and CrN, deposited on steel substrates by an arc ion plating method, heat treatment was carried out at various temperatures ranging from 733 to 1333 K, and the effects of heat treatment and heating temperature on mechanical properties of these films were investigated. For all films, the adhesive strength was improved effectively by heat treatment. This improvement could be explained by the formation of a diffusion layer between the film and the substrate in the heat treatment process. Wear resistance was also improved by heat treatment in all the films, though hardness decreased. It was also found that the friction coefficient in each film was decreased by the heat treatment, and this decrease in friction coefficient could be one reason why wear resistance was improved.

Heat input during the welding process and subsequent re-cooling changes the microstructure, hardness, toughness, and cracking susceptibility in heat affected zone (HAZ). Weld quality of a weldment largely depends on the area of HAZ. Determination of exact area of the HAZ by manual stereological methods and conventional visual inspection techniques is a difficult task. These techniques of evaluation are based on approximating the complex shape of HAZ as combination of simplified shapes such as rectangles, triangles etc. In this paper, a filtering scheme based on morphology, thresholding and edge detection is implemented on image of weldments to assess quality of the weld. The HAZ of mild steel specimens welded at different welding parameters by Metal Active Gas/Gas Metal Arc Welding process were compared and presented.

Welding is a complicated physicochemical process and residual plastic strains are the product of nonlinear behaviors of the structure during it. Distortions of a welded structure injure the beauty of appearance of it while they cause errors during the assembly of the structure and reduce the strength of the structure. Nonlinear three-dimensional transient temperature fields are analyzed by FEM first. The heat source is modeled as a moving heat flux following a Gaussian distribution. In the process of analysis, the temperature dependent properties of materials and enthalpy are considered. Doing the welding experiment for a fundamental fillet welding model is to verify the numerical results, the infrared thermograph is used to follow and record the whole experiment process. The results of temperature field in FEM are supported by experimental data. Then, an elastic-plastic-model is established to analyze the residual strains under the temperature loads. The distortions of a simple stainless steel stiffened structure and a ship structure are obtained respectively. In addition, the residual distortions of the stiffened structure are measured by laser measurement. The residual distortions, namely, in-plane shrinkage and out-of-plane distortion are supported by the experimental data.

Microsatellites are the lowest price spacecrafts for lunch to their orbit. As a result, recently they are extensively employed in space missions. In these satellites it has been tried to use less heavy and simple hardware with higher reliability and energy efficiency. Magnetorquers are mainly used in Satellite Attitude Control Systems (ASC) as a control actuator. These actuators generate desired controllable torques. The Magnetorquers have the characteristics of a relatively lightweight and they also require no moving parts, expendables, and complex hardware. These minimum requirements have motivated scientific community to employ actuators in spacecrafts extensively. This paper presents Design procedures and manufacturing of a research magnetorquer in Aerospace Research Laboratory of K.N.Toosi University of Technology, Iran. Firstly, a mathematical model for design of a magnetorquer is explained, and the significant parameters for manufacturing of an efficient actuator are extended. Then Strategic Planning for design of a magnetorquer is expanded. At the end driver and demagnetization circuits are presented and the research magnetorquer with its participant circuits are discussed.

In today's world satellites have an immense and profound role in a country's financial, social and military development and having the technology of creation and launching satellites is a yard stick to a country's progress. Each satellite, like any other advanced machine is consisted of many subsystems in order to do its mission, among those, the attitude Control subsystem has the duty of stabilizing and orientation. Depending on the type of stabilization and control laws, different actuators like momentum wheels, reaction wheels, magnetic torquers and etcetera are used. Due to its smaller shape and weight, lower cost and minimal power consumption, the magnetic torquer is frequently used in low-earth orbit satellites. A magnetic torquer is consisted of a winding wire and a magnetic core that with the current of electricity passing through the winding wire, a magnetic dipole moment is produced. In reaction to the earth's magnetic field, this moment produces the required torque. Thus, having a broader understanding of the specification of the magnetic torquer before using it in the satellite is quite necessary. As a result, in this paper we try to show how to make such system in the laboratory. A magnetorquer is manufactured that the main idea is to estimate the magnetic dipole moment from the magnetic field measurement by this magnetic torquer. To achieve this, first we talk about the theories of creating such device and test system, then we will delve into the more technical aspects of designing such subsystem. In the end, from the output results, the performance curve of the magnetic torquer is produced and the linear areas and scale coefficients are determined. This paper presents test methodology, experimental setup and test results of manufacturing a torque rod with CK30 ferromagnetic alloy core.

With the increase of space activities, space debris environment has deteriorated. Space debris impact shields of spacecraft creates debris cloud, the debris cloud is a threat to module wall. In order to conduct an assessment of spacecraft module wall damage impacted by debris cloud, the damage position must be known. In order to design a light weight location system, polyvinylidene fluoride (PVDF) has been studied. Hyper-velocity impact experiments were conducted using two-stage light gas gun, the experimental results indicate that: the virtual wave front location method can be extended to debris cloud impact location, PVDF can be used to locate the damage position effectively, the signals gathered by PVDF from debris cloud impact contain more high frequency components than the signals created by single projectile impact event. The results provide a reference for the development of the sensor systems to detect impacts on spacecraft.

This study was aimed to apply the use of ultrasonic welding to weld round plastic tubes. The ultrasonic welding machine was designed to be able to work with a normal ultrasonic welding transducer by rotating the tube while it is being welded. The specimens used in this study were round plastic tubes (PMMA) with diameter of 35 mm and 2 mm thickness. End of each tube was machined to have angle of 2.8, 3.8 and 5.7 degree in order to create contact angle at the interface. The specimens were welded with frequency of 28 kHz and tube rotational speeds of 25 rpm, 45 rpm and 100 rpm. The axial force was applied to the tube in order to enhance the quality of joint. The experimental result revealed that the modified ultrasonic welding machine can generate the welded area around the circumference of tube. It was found that the axial force and contact angle have some effect to the quality of joint. The contact angle of 2.8/2.8 provided highest welded area compared to 3.8/3.8 and 5.7/5.7 degree of contact angle. In addition, the axial force between 80 N - 120 N provided high value of welded area. The pattern of welded area is also presented and discussed in the paper.

In the process of optoelectronic reconstruction of color holograms, the reconstructed images of three colors can't be overlap properly because transverse dispersion caused by different wavelengths of three laser beams of R, G, B colors. In this paper, a novel method is proposed to compress or expand the number of discrete pixels of three component color images for eliminating transverse dispersion in the process of computing holograms. Holograms computed by the iterative Fourier transverse algorithm (IFTA) were loaded on reflective liquid crystal spatial light modulator (LC-SLM) for optoelectronic reconstruction. The experimental result shows that the method is effective.

Digital holography allows recording the hologram using digitally imaging devices such as CCD, and reconstructing the holographic image by numerically simulating the diffraction of the hologram. Its main advantages are by which one can directly obtain the complex amplitude distribution of the object field, so that more impersonally measure the detail information of the object field, such as the distribution of the refractive index changing in crystals induced by light irradiation, deformation of the object surface, particle distribution, as well as acoustic field, flow field and temperature distribution in air. In this paper, we summarize the principle and some of our experimental results on the applications of digital holography in visualized measurement of acoustic standing wave (acoustic levitation field), plasma plume and water flow (Karman vortex street) fields.

In this paper, we propose a method for optical image encryption based on fractional Fourier transform (FRFT) and Arnold transform (ART) in phase-shifting digital holography. An input image is first divided into eight bit planes, and each bit plane is encrypted based on double random-phase masks and FRFT. Complex amplitude for the object is retrieved by phase-shifting digital holography in the hologram plane. The real and imaginary parts of the retrieved complex amplitudes for the 0th-7th bit planes are further encrypted using ART algorithm. Numerical results are shown to demonstrate the feasibility and effectiveness of the proposed technique. The sensitivity of security parameters, such as function orders in FRFT and iteration number in ART method, is also analyzed.

In this present study an attempt has been made to reduce the complexities of the digital recording and reconstruction processes through the use of a Gates interferometer employing a plane parallel beam. The use of a single cube beam-splitter for the recording process serves to eliminate phase noises associated with use of multiple optical elements. The proposed technique is discussed in detail and some reconstructions are presented.

Three different methods of stress measurement with strong spatial resolution are presented. They base on stress relief techniques caused by focused ion beam milling, on altered electron backscattering by deformed lattices and on Stokes line shift measurements by Raman spectroscopy. The capability of these methods is demonstrated by their application to typical MEMS structures. A comparison between the methods is performed in order to outline potentials and limitations.

In order to examine the mechanism of splitting failures of silicon nitride balls under cyclic pressure loads, we carried out the fatigue tests of pre-cracked balls. In our previous works, we discovered that splitting failures of the balls were caused by pre-cracks which were initiated on their equators by Vickers indenter. In the present work, in order to further investigate this phenomenon, we carried out fatigue tests of two size balls (4.762mm and 9.525mm). We focus on the growth behavior of cracks whose initial length ranged from 0.260 to 0.290μm and discuss about the effects of ball diameters on the fatigue strength. Based on the empirical features of the two balls, we found that the initial threshold limits of the equivalent stress intensity factor ranges ▵K_eq for each ball were different. In order to look into this, we measured the residual stresses using the X-ray stress measuring method.

The aim of this work is to investigate static and thermal-mechanical strength and fatigue behaviors of steel honeycomb sandwich beams through three-point bending. The bending strength limits at different experimental temperatures (room temperature, 200, 300 and 400°C, respectively) are obtained. The bending fatigue behaviors at high temperature are discussed and the fatigue test results are presented in standard S/N diagrams. Meanwhile damage and failure modes are reported and analyzed. Effects of the honeycomb cell orientation (L or W) on the maximum load and on the damage processes are also investigated.

This study aims obtain a precise strength of a glass fiber/ epoxy resin interface by taking non-elastic analysis which might be very important factor to be considered. A cruciform specimen method is one of the reasonable tests to investigate interfacial strength. Varying the cruciform angles, the interfacial failure criterion under combined stress-state can be obtained. However, when the interfacial strength is beyond the matrix yield stress, non-elastic stress analysis must be done in order to obtain the interfacial strength precisely. In this study, the non-elastic analysis is performed and the effect is discussed.

Engineering components made of soda-lime glass sometimes contain notches with different shapes, particularly V-shaped notches. A V-notch plays the role of a stress concentrator that dramatically decreases the load bearing capacity of the component. Since fracture in soda-lime glass occurs suddenly due to its brittleness, it is necessary to estimate the fracture resistance of V-notched glass components under different loading conditions. In this research, the fracture behavior of glass components containing a rounded-tip V-notch was studied both experimentally and theoretically under mixed mode I/II loading. A wide range of mixed mode fracture tests were performed on the rounded-tip V-notched Brazilian disc specimens made of soda-lime glass. A mixed mode failure criterion was then used for predicting fracture initiation angle in the tested specimens. It was shown that the experimental results can be successfully predicted by using the results of the proposed criterion.

Within the framework of the theory of linear piezoelectricity, a study on linear contributions of the total energy release rate in fracture of the piezoelectric material with a Griffith crack perpendicular to the poling axis was carried out by using the double-torsion technique. The three linear contributions of the total energy release rate due to linear processes are related to the pure mechanical and the electromechanical (or piezoelectric) compliance, and the pure electrical capacitance of the piezoelectric specimen, respectively. For determination of the contributions, the mechanical and the electromechanical (or piezoelectric) compliances were calculated from the measured load-displacement curves at each electric field, and the electric capacitance was obtained from the property and geometric dimension of the sample. In this work, we defined that the pure mechanical compliance and the pure electrical capacitance are the constant values according to the geometrical size as the intrinsic values without considering the electric effects and the mechanical effects, respectively, but the piezoelectric compliance is a dependent variable owing to the electromechanical coupling effects. As the results based on these definition, it was found that the piezoelectric behaviors related to the piezoelectric compliance aid the fracture of C-82 piezoelectric ceramic irrespective to the direction of electric fields and have more influence on the positive electric fields, and the total energy release rate, G_tot (=G_m + G_p) in permeable crack model is more effective than the mechanical one, GM in this research.

In the high energy processing using explosive, there are variety of application examples which is explosion welding of differential metallic plate and powder compaction of diamond. However a rule legal to explosives is severe and needs many efforts for handling qualification acquisition, maintenance, and security. In this research, the metallic foil explosion using high current is paid my attention to the method to obtain linear or planate explosive initiation easily, and the main evaluation of metallic foil explosion was conducted. The explosion power was evaluated by observing optically the underwater shock wave generated from the metallic foil explosion.

The foam aluminum belongs to multi-cell materials, and it has good mechanical performance, such as large deformation capacity and good energy absorption, and usually used as core material of sandwich panel, now it is widely used in automotive, aviation, aerospace and other fields, particularly suitable for various anti-collision structure and buffer structure. In this article, based on an engineering background, the INSTRON4505 electronic universal testing machine and split Hopkinson pressure bar (SHPB) were used for testing the static and dynamic mechanical properties of sandwich panel with different thickness steel plate- foam aluminum core, from the results we can see that the steel plate thickness has big influence on the stress-strain curve of the sandwich panel, and also takes the sandwich panel with 1mm steel panel to study the material strain rate dependence which under different high shock wave stress loaded, the results show that the sandwich panel is strain rate dependence material. And also, in order to get good waveforms in the SHPB experiment, the waveform shaped technique is used in the dynamic experiments, and the study of this paper will good to sandwich panel used in the engineering.

Magnesium alloys have been increasingly used in the automobile, communication and aerospace industries due to their low density, high specific strength and good castability. Higher speed in vehicles, development in weaponry and high speed metal working all are characterized with high rates of loading. In current study, a cast magnesium alloys AZ91D has been investigated at strain rates in the range between 300 s^-1 and 1250 s^-1. Relatively uniform strain rates are observed at lower strain rates. However an exception is observed for maximum strain rate tested, where a nearly constant strain rate of 1252 s^-1 is observed over most of the test duration. Approximately 25% increase in stress is noticed at a strain rate of 1252 s^-1 as compare to the stress at a strain rate of 346 s^-1. The alloy AZ91D is observed to be more strain rate sensitive for strain rate higher than 1000 s^-1. A decrease in strain rate sensitivity is observed with increasing percentage strain in the specimen.

A 3D Fourier transform for vibration measurement of an object based on shadow moiré technique is presented. A sinusoidal grating is placed closed to a vibrating object. The moiré fringe patterns generated by the interference of grating lines and shadow lines are captured by a high-speed camera. The joint spatial and temporal information of the fringe sequence is processed by use of the 3D Fourier transform simultaneously rather than separately, then a 3D space-time phase distribution can be obtained from the filtered spatiotemporal spectra. From the phase values, the surface profile, and displacement of the object at different time can be retrieved. The experiment for measurement of a vibrating cantilever beam is used to demonstrate the validity of the technique. The results show that shadow moiré with spatiotemporal analysis can be applied to dynamic measurement.

A new kind dynamic photoelastic system is constructed which includes high-speed photography system and digital image processing system. The dynamic photo elasticity system catches the force process of different epoxy resin specimens under static load and impact load in circularly polarized. It was a sample to use high-speed camera to study the process of the material internal stress transmission under impact load. The photos were caught in the force process to study and analyze the movement and law of isochromatic fringe pattern. The stress's values of Integer fringes in the force process were counted. After finished the experiment, we discussed the feasibility to improve the lamp-house, image resolution and the time of exposure.

Mechanical analysis of bottom hole assembly(BHA) is the basis of well trajectory control technology. Considering the displacement and force boundary conditions of drillstring and testing axial excitation force of bottom column, axial acceleration of head column, transverse displacement of columns and collision and contact forces between inner columns and outer pipe, dynamics experimental device of column-liquid interaction is built to do two kinds of test: the column vibrating test under the conditions of different vibrating frequency and different axial excitation force and the column rotating test under the conditions of different axial excitation force, different rotating speed and different flux. The experimental results show that the changes of vibrating frequency and the flow has little effect on axial vibrating force of bottom column and radial displacement of column, but the existence of the liquid will reduce the axial force amplitude of bottom column; With the speed increased, radial displacement of the column and the segments of the collision and contact column between the column and the pipe increase and the columns have the phenomenon of multi-segments swing. It is to provide the device and means to study dynamics movement rules of rotating column in the pipeline.

In the present study, a universal split Hopkinson pressure bar (SHPB) device has been employed to investigate the dynamic properties and damage patterns of alumina (A95) ceramic under axial compression under strain rate ranging from 280~400s^-1. Different shapes of loading pulses were generated with variety shaper materials. By changing input pulse shape, the experiment results showed that the damage patterns changes from fragmentation by axial splitting to totally smashed into acerate pieces. Based on the experiment results and other literature data, a Johnson-Holmquist 2 (JH-2) constitute model parameters were determined. The mechanical model and constants were used to provide inside details of A95 ceramic damage models under SHPB test under different input pulse shapes. A direct impact experiment was held to compare with the dynamic numerical results, in order to clarify the A95 ceramic response under low velocity impact and the applicability for JH-2 model.

Ejecta is the new debris produced by micrometeoroid or small space debris impacting on spacecraft surface. It is one of the main increasing sources in the number of space debris. Researching of space debris hypervelocity impacting on the typical material of spacecraft surface could gain the distribution of ejecta and provide a input source for the space debris environment model. In this paper, 2017 aluminum sphere projectiles of 2.4mm and 3.2mm diameter are accelerated to about 2km/s and 3km/s using a two-stage light-gas gun. The data of speed, quality, size for ejecta is analysised by the probability theory of mathematical statistics, then get the speed, quality, size distribution of the ejecta and set up the ejecta model. The average size and velocity of the ejecta increase with increasing of the diameter and velocity of the projectile. The zenith angle of the ejecta is almost between 39° and 47°.

The finite element method is used in various approaches to solve biomechanical problems. We present a concept helping in the development of appropriate models of the implant-bone compound based on different software packages. The reconstruction of bone morphology is based on computed tomography (CT) data of the designated bone. After the bone is three-dimensionally reconstructed in the CAD-environment, virtual implantation can be undertaken. Differentiation of cortical bone and trabecular bone is realised by mapping the Hounsfield Units (HU), which are a measure of attenuation, from the CT-slices onto the nodes of the FE-mesh. The HU are mathematically treated as temperatures and are correlated with calcium density respectively bone stiffness in a temperature-dependent material model. In order to validate the presented approach, an experimental test-setup using a fresh-frozen human hemipelvis was designed. Rosette strain gauges were placed on the bone at five locations and a load corresponding to the maximum force during the gait cycle was applied by means of a universal testing machine. The same force was applied in the FE-model and the strain distribution as well as the micromotion was calculated. The minimum principal strains as a result of compression were calculated with a correlation coefficient of r² = 0.94 resp. r² = 0.86. Our concept is aimed at predicting the stress and strain states in the bone stock and within the implant and has the potential to predict relative interfacial micromotion.

In connection with technological advances in the manufacturing of medical ceramics, a newly developed ceramic femoral component was introduced in total knee arthroplasty (TKA). The motivation to consider ceramics in TKA is based on the allergological and tribological benefits as proven in total hip arthroplasty. Owing to the brittleness and reduced fracture toughness of ceramic materials, the biomechanical performance has to be examined intensely. Apart from standard testing, we calculated the implant performance under different worst case scenarios including malposition, bone defects and stumbling. A finite-element-model was developed to calculate the implant performance in situ. The worst case conditions revealed principal stresses 12.6 times higher during stumbling than during normal gait. Nevertheless, none of the calculated principal stress amounts were above the critical strength of the ceramic material used. The analysis of malposition showed the necessity of exact alignment of the implant components.

The growth of large and high quality protein crystals has been a bottleneck for the determination of three dimensional structures and medicines design. Failure to prepare large crystals can be partly attributed to a lack of understanding of the crystal growth process. In this paper, a real-time optical diagnostic system consisting of the Mach-Zehnder interferometer with the phase-shift device, a microscope and an image processor has been developed for the study of the kinetics of the crystal growing process. The crystallization of NaCl was investigated to simulate protein crystallization method of vapor diffusion with an oil barrier. 1) The relative refractive index could be obtained from four-step phase-shift algorithm. 2) Fourier analysis and Windowed Fourier analysis were applied in the spatiotemporal domains to extract evolution of the absolute refractive index profile, which has not appeared before as far as we know. 3) The comparison of Fourier analysis and windowed Fourier analysis in phase and velocity measurements is also presented. The experiment has a major theoretical and practical significance in the domain of crystal growth experiments and crystal optimization.

Development of a low-cost, yet reliable, system for 2D gait analysis is presented in this paper. The system consists of a home video camera with speed of 25 fps, LED markers, PC and a technical computing software, which are used for capturing and processing the digital image of markers attached to human body during motion. In the experiments, a person is instructed to walk in a specially arranged measurement area. The recorded images are then digitally processed to detect and track the 2D coordinate of the markers over time. To conduct a dynamics analysis, a mathematical formulation for human motion is constructed where the body is modeled by a system of five rigid bars connected by joints. Finally, a program is developed to plot and calculate the kinematics and dynamics data of human gait, where the markers position data over time, and other variables such as dimensions and weight of the body are used as the input in the program.

MEMS systems are technologically developed from integrated circuit industry to create miniature sensors and actuators. Originally these semiconductor processes and materials were used to build electrical and mechanical systems, but expanded to include biological, optical fluidic magnetic and other systems [12]. Here a novel approach is suggested where in two different fields are integrated via moems, micro fluidics and ring resonators. It is well known at any preliminary stage of disease onset, many physiological changes occur in the body fluids like saliva, blood, urine etc. The drawback till now was that current calibrations are not sensitive enough to detect the minor physiological changes. This is overcome using optical detector techniques [1]. The basic concepts of ring resonators, with slight variations can be used for optical detection of these minute disease markers. A well known fact of ring resonators is that a change in refractive index will trigger a shift in the resonant wavelength [5]. The trigger for the wavelength shift in the case discussed will be the presence of disease agents. To trap the disease agents specific antibody has to be used (e.g. BSA).

The understanding of heat transfer in human teeth is important for optimizing clinical practice protocols and daily intake instructions. However, it is technically challenging to study the in vitro thermal behavior of human tooth due to its small size and complex biological/geometrical structure. The currently widely used method is based on thermocouples, which has several limitations such as low spatial resolution, contact measurement and, in particular, lack of whole-field information. To address these challenges, an experimental system was developed to measure the whole-field temperature distribution in human tooth in vitro. The human tooth sample was heated at the tooth crown with flowing hot water (60 °C) for 10 s and then cooled down by natural convection of air. The temperature of the whole sectioned sample surface was recorded using an infrared camera. The results demonstrate that the developed system is capable of measuring temperature evolution in small human tooth samples. The biological junction of tooth (e.g., dental-enamel junction) is shown to have great influence on its heat transfer behavior. The present study could open the door for several future applications, e.g., systemic investigation of heat transfer in intact/restored tooth heated with clinical methods for treatment optimization, and measurement of thermal properties for different tooth layers.

The aim of this study is to evaluate the biomechanical changes after Spinous Process Osteotomy (SPO) with different amounts of facetectomy of the lumbar spine and to compare the models with SPO and intact models using finite element models. Intact spine models and one decompression models (L3-4) with SPO were developed. SPO models included three different amounts of facetectomy (25%, 50%, and 75%). After validation of the models, finite element analyses were performed to investigate the ranges of motion and disc stresses at each corresponding level among three SPO models and intact lumbar spine models. The ranges of motion in the SPO models were increased more than the intact models. According to increase of amounts of facetectomy, ranges of motion were also increased. Similar to range of motion, the von Mises stress of disc in the SPO models was higher than that of intact models. Moreover, with the increase of amount of facetectomy, the disc stress increased at each segments under various moments. The decompression procedures using spinous process osteotomy has been reported to provide better postoperative stability compared to the conventional laminectomy. However, facetectomy over 50 % is likely to attenuate this advantage.

During the life time of a cell, it goes through changes to the plasma membrane as well as its internal structures especially distinctive during processes like cell division and death. Different types of microscope are used to fulfill the observation of the cell's variation. In our experiment, Vero cells have been investigated by using phase contrast microscopy and digital holographic microscopy (DHM). A comparison of the images obtained for cell division is presented here. The conventional phase contrast microscope provided a good imaging method in the real time analysis of cell division. The off-axis digital hologram recorded by the DHM system can be reconstructed to obtain both the intensity image and phase contrast image of the test object. These can be used for live cell imaging to provide multiple results from a single equipment setup. The DHM system, besides being a qualitative tool, is able to provide quantitative results and 3D images of the cell division process. The ability of DHM to provide quantitative analysis makes it an ideal tool for life science applications.

Human hair is a complex nanocomposite fiber whose physical appearance and mechanical strength are governed by a variety of factors like ethnicity, cleaning, grooming, chemical treatments and environment. Characterization of mechanical properties of hair is essential to develop better cosmetic products and advance biological and cosmetic science. Hence the behavior of hair under tension is of interest to beauty care science. Human hair fibers experience tensile forces as they are groomed and styled. Previous researches about tensile testing of human hair were seemingly focused on the longitudinal direction, such as elastic modulus, yield strength, breaking strength and strain at break after different treatment. In this research, experiment of evaluating the mechanical properties of human hair, such as Young's modulus and Poisson's ratio, was designed and conducted. The principle of the experimental instrument was presented. The system of testing instrument to evaluate the Young's modulus and Poisson's ratio was introduced. The range of Poisson's ratio of the hair from the identical person was evaluated. Experiments were conducted for testing the mechanical properties after acid, aqueous alkali and neutral solution treatment of human hair. Explanation of Young's modulus and Poisson's ratio was conducted base on these results of experiments. These results can be useful to hair treatment and cosmetic product.

The aim of this study is to investigate the change in biomechanical milieu following removal of pedicle screws or removal of spinous process with posterior ligament complex in instrumented single level lumbar arthrodesis. We developed and validated a finite element model (FEM) of the intact lumbar spine (L2-4). Four scenarios of L3-4 lumbar fusion were simulated: posterolateral fusion (PLF) at L3-4 using pedicle screw system with preservation of PLC (Pp WiP), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system with preservation of PLC (Pp WoP), L3-4 using pedicle screw system without preservation PLC (Sp WiP), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system without preservation of PLC (Sp WoP). For these models, we investigated the range of motion and maximal Von mises stress of disc in all segments under various moments. All fusion models demonstrated increase in range of motion at adjacent segments compared to the intact model.For the four fusion models, the WiP model s P had the largest increase in range of motion at each adjacent segment. This study demonstrated that removal of pedicle screw system and preservation of PLC after complete lumbar spinal fusion could reduce the stress of adjacent segments synergistically and might have beneficial effects in preventing ASD.

The Image Pattern Correlation Technique (IPCT) in combination with high-speed stroboscopic imaging enables nonintrusive measurements of surface deformation of fast vibrating or rotating objects. This paper describes a dedicated instrumentation for the measurement of the deformation of aircraft propellers as well as the results of its application. The further ideas of imaging technologies based on the collected experiences, in particular the high-power pulsed object illumination based on semiconductor light sources are also presented.

This paper presents a comparative study on technique to achieve high compression ratio in video coding. The focus is on the Block Matching Motion Estimation (BMME) techniques. It has been particularly used in various coding standards. In the BMME, search patterns and the center-biased characteristics of motion vector (MV) have large impact on the search speed and quality of video. Three fast Block Matching Algorithms (BMAs) of motion estimation through block matching have been implemented and performance of these three has been tested using MATLAB software. The Cross Diamond Search (CDS) is compared with Full Search (FS) and Cross Search (CS) algorithms based on search points (search speed) and peak signal-to-noise ratio (PSNR) as the quality of the video. The CDS algorithm was designed to fit the cross-center-biased (CCB) MV distribution characteristics of the real-world video sequences. CDS compares favorably with the other algorithms for low motion sequences in terms of speed, quality and computational complexity. Keywords: Block-matching, motion estimation, digital video compression, cross-centered biased, cross diamond search.

A digital image correlation (DIC) method has sufficient high accuracy at the time of infinitesimal deformation. However, mismatching may arise depending on the texture of an image and the right result may be unable to be obtained. Although accuracy improved more to enlarge subset size, the demerit of which the computation time increases and it cannot respond to a small image existed. Therefore, when subset size was set small, improvement in the accuracy of the digital image correlation method was investigated by aiming to reduce mismatching. The accuracy by the coarse-to-fine approach of performing coarse search by the image on which resolution was dropped first, and performing fine search by a high-resolution image after that was examined. In the digital image correlation method using coarse-to-fine approach, the result checked that an accurate result was obtained, without mismatching occurring, even when subset size was set up small. Moreover, in the digital image correlation method using the sum of absolute difference (SAD) method, it was possible to have analyzed with accuracy almost equivalent to the digital image correlation method by a correlation coefficient, and it succeeded also in reduction of mismatching at the time of setting up subset size small.

The creep behavior of the polymer bonded explosive (PBX) substitute material is investigated by using the digital image correlation (DIC) method. At first step the 3-points bending test is applied to achieve the tested PBX substitute material's elastic parameters, which are identified by the calculated heterogeneous strain fields and the so-called virtual fields method (VFM). In the second step, the creep property of PBX material is studied by the Brazilian disc compression test. The stress fields could then be reconstructed with the identified elastic parameters and the strain fields at the first step of loading. The time hardening coefficients which present the creep behavior could be extracted by the time-depending strain rate curves of the points on the surface.

The directivity function of orthotropic piezoelectric composite materials (OPCM) ultrasonic linear array is deduced by constructing a mathematic model of acoustic field on a new OPCM ultrasonic phased array actuator/sensor, which is based on the 1-1 mode OPCM. By calculating scatter feature of acoustic field in space and analyzing the effects of change in structure type and dimension on main lobe and side lobe of array, optimal array parameters of new OPCM ultrasonic phased array actuator/sensor, such as operating frequency, array interval, array width and array number are obtained. The developed OPCM actuator/sensor elements are applied in detecting the simulated damage in aluminum plate. The testing results show that the damage detection precision is further improved by using OPCM ultrasonic phased array actuator/sensor.

Quartz crystal microbalances (QCMs) in contact with liquid droplets have been used to investigate the rheological properties of liquids and the diverse solid-liquid interfacial phenomena. In this article, we first report the experimental results of the QCM responses due to the deposition of microliter droplets of silicone oils. The silicone oils with viscosity in a range from 50cS to 10³cS are tested. It has been found that the responses in the frequency and resistance measurements of the QCM in contact with the silicone oils are different from the Newtonian liquids. More importantly, it has been found that for the silicone oils the frequency of the QCM steadily increases for several hours and even exceeds the initial value of the unloaded QCM which has resulted in the positive frequency changes. The collaborative effects of the interfacial slip and viscoelasticity have been discussed to qualitatively interpret the positive frequency changes. Secondly, we discuss the cyclical variations in the frequency and resistance during the experiments of the silicone oils, which are attributed to the generation of the compressional wave in the droplets. The present work has shown some phenomena which need to be taken into consideration when using the droplet QCM as a rheological sensor and may stimulate the ongoing research on the related issues in the QCM community.

In high-speed and high-precision control of a precision stage for semiconductor manufacturing, vibration of the axially moving factors leads to operational problems and limits their utility in many applications. Reaction force and vibration controls are a key to improve the control performance. In this paper, the novel design method of the precision position control system integrated with both the reaction force control and the vibration control system is proposed. The proposed method is constructed of the multi-input and multi-output (MIMO) modeling based on the subspace method and the controller design based on the position control, decoupling control and vibration control. In the design of the complex control system, the design parameters are only the identified plant model and the control bandwidth. The effectiveness of the proposed integrated design method is verified through the experiments using the developed 6-degree-of-freedom (6DOF) experimental setup.

A FBG sensor multiplexing system based on the combination of wavelength- and time- division multiplexing technique is proposed. In this paper, A semiconductor optical amplifier (SOA) connected in a ring cavity is used to serve as a gain medium and switch. The sensor array is consisted of four groups of sensors and the nominal wavelength of the sensors in the same group is different. The SOA is driven by a pulse generator which switch on the SOA at different periods, as a switch to select the reflected pulses from a particular group. Using low reflectivity (3%~5%) sensors the number of the groups can achieved 50, the bandwidth of each group used in this system is 40 nm (1525-1565nm), the system permits the interrogation of up to 1000 FBG sensors. With this technique, the FBG sensors system avoid using optical switch to expand channels, it improved the response speed and reduced cost in the application of structural health monitoring where large numbers of sensors are required.

Haptic feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, very long and stiff bar of instruments take haptic feeling away from the surgeon. In minimally invasive robotic surgery (MIRS), moreover, haptic feelings are totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peakforce magnitude by at least a factor of two. Therefore, it is very important to provide haptic information in MIRS. Recently, many sensors are being developed for MIS or MIRS, but they have some obstacles in their application to real situations of medical surgery. The most critical problems are size limit and sterilizability. Optical fiber sensors are one of the most suitable sensors for this environment. Especially, optical fiber Bragg grating (FBG) sensor has one additional advantage than the other optical fiber sensors. FBG sensor is not influenced by intensity of light source. In this paper, we would like to present the initial results of study on the application of the FBG sensor to measure reflected forces in MIRS environments and then suggest the possibility of successful application to the MIRS systems.

A typical way to produce biodiesel is the transesterification of plant oils. This is commonly carried out by treating the pre-extracted oil with an appropriate alcohol in the presence of an acidic or alkaline catalyst over one or two hours in a batch reactor.Because oils and methanol are not completely miscible. It has been widely demonstrated that low-frequency ultrasonic irradiation is an effective tool for emulsifying immiscible liquids. The objective of this research is to investigate the optimum conditions for biodiesel production from crude Jatropha curcas oil with short chain alcohols by ultrasonic cavitation (at 40 kHz frequency and 400 Watt) assisted, using two step catalyst method. Usually, the crude Jatropha curcas oil has very high free fatty acid which obstructs the transesterification reaction. As a result it provides low yield of biodiesel production. In the first step, the reaction was carried out in the presence of sulfuric acid as an acid catalyst. The product was then further transesterified with potassium hydroxide in the second step. The effects of different operating parameters such as molar ratio of reactants, catalyst quantity, and operating temperature, have been studied with the aim of process optimization. It has been observed that the mass transfer and kinetic rate enhancements were due to the increase in interfacial area and activity of the microscopic and macroscopic bubbles formed. For example, the product yield levels of more than 90% have been observed with the use of ultrasonic cavitation in about 60 minutes under room temperature operating conditions.

Fiber bragg grating (FBG) sensors have been widely used for number of sensing applications like temperature, pressure, acousto-ultrasonic, static and dynamic strain, refractive index change measurements and so on. Present work demonstrates the use of FBG sensors in in-situ measurement of vacuum process with simultaneous leak detection capability. Experiments were conducted in a bell jar vacuum chamber facilitated with conventional Pirani gauge for vacuum measurement. Three different experiments have been conducted to validate the performance of FBG sensor in monitoring vacuum creating process and air bleeding. The preliminary results of FBG sensors in vacuum monitoring have been compared with that of commercial Pirani gauge sensor. This novel technique offers a simple alternative to conventional method for real time monitoring of evacuation process. Proposed FBG based vacuum sensor has potential applications in vacuum systems involving hazardous environment such as chemical and gas plants, automobile industries, aeronautical establishments and leak monitoring in process industries, where the electrical or MEMS based sensors are prone to explosion and corrosion.

This paper considers the transverse vibrations of a line beam system carrying a discrete masses on the elastic foundation. The line beam system consists of step-up beams associating among themselves elastic hinges with one or two degrees of freedom. The series of discrete masses are connected elastically in the separate sections of the beam system. The elastic foundation has piecewise-constant coefficient of rigidity except concentrated inclusions in the form intermediate elastic supports and fixturings. The mathematical model of continuum discrete system is offered here. The solution of differential equations is found analytically using spline-transformation's method. The program MOCODISS (Modeling of Continuous-Discrete Systems) realizes the developed algorithms. MOCODISS gives the means for creating of calculation models for beam type in interactive mode using graphic and tabular editors. There are visual means for creating beam elements with piecewise-constant conditions, elastic hinges with one or two degrees of freedom, rigidly fixed masses, separate elastic supports and/or fixturings, piecewise-constant elastic foundation and the series of masses connecting with the beams. In mode of calculation's results we can used structural monitoring of beam elements,elastic hinges and elastic foundation in the graphic and writing forms. The validity of developed algorithms is confirmed by comparison with the numerical and experimental data of other researches.

The wheelset is normally processed into a rigid body in vehicle dynamics simulation but for the high speed train the impact resulting from the elastic vibration of the wheelset on the vehicle system vibration characteristics can not be ignored. The paper introduces the flexible dynamics method in the trailer wheelset vibration performance and dynamic stress research. The flexible model of wheelset is set up using substructure method in ANSYS Code and the whole vehicle system dynamics model is obtained by SIMPACK Code. The vibration behavior of wheelset and the wheel-rail forces are presented and then the dynamic stress of the axle is analyzed. 300 km/h EMU online test is carried out and the result comparison between the testing data and data from simulation shows the reliability and feasibility of the dynamics model proposed.

It is a common understanding by manufacturers of precision machines that vibrations are a potentially disastrous threat to precision and throughput. To satisfy the quest for more stable processes and tighter critical dimension control in the microelectronics manufacturing industry, active vibration control becomes increasingly important for high-precision equipment developers. This paper introduced the development of an active vibration isolation system for precision machines. Innovative mechatronic approaches are investigated that can effectively suppress both environmental and payload-generated vibration. In this system, accelerometers are used as the feedback sensor, voice coil motors are used to generate the counter force, and a TI DSP controller is used to couple sensor measurements to actuator forces via specially designed control algorithms in real-time to counteract the vibration disturbances. Experimental results by using the developed AVI prototype showed promising performance on vibration attenuation. It demonstrated a reduction of the settling time from 2s to 0.1s under impulsive disturbances; and a vibration attenuation level of more than 20dB for harmonic disturbances. The technology can be used to suppress vibration for a wide range of precision machines to achieve fast settling time and higher accuracy.

In this paper, the CNS are considered as the Euler-Bernoulli beams which have been used in many references about the CNS. Taken the thermal-mechanical coupling into account, the variational principle for the CNS is presented by the variational integral method. With the derivation of the varitional principle, the stationary value conditions are obtained. At last, the vibration governing equation is illustrated, which will be benefit for the numerical simulation with finite element method in further investigations. From the stationary value conditions deduced by the variational principle, it can be observed that the vibration characteristics of the CNS can be influenced by the temperature changes. It is expected to be useful for the design and application of the nano scale devices.

The traditional finite element method (TFEM) of analysis requires a large number of elements to have a detailed description of the structure. Other semi-analytical method with additional degree-of-freedoms (DOFs) within an element overcomes this problem, but any revision in the model needs a reformulation of the finite element model for computation. The wavelet finite element method (WFEM) has the advantage of multi-resolution analysis whereby both coarse and detailed descriptions of the structure can be obtained. This paper presents the WFEM based on B-spline wavelet on the interval (BSWI). The shape function is formed by scale function of BSWI and a transformation matrix is constructed between the wavelet and the physical spaces. All the physical parameters in the system are expressed in terms of the transformation matrix and scale function of BSWI. The multi-resolution property of the WFEM is demonstrated with the inverse analysis of moving force identification using several distributed measured dynamic responses. The dynamic programming technique and Tikhonov regularization are used for the identification. Numerical results show that the WFEM has similar accuracy as the TFEM under the same conditions but with fewer finite elements, while the first-order Tikhonov regularization is found capable to remove most of the effect of measurement noise.

Rubber engine mounts are commonly used to provide v ibration attenuation. The loss factor and dynamic stiffness of engine mount provide fundamental information of the energy dissipation. This paper presented the effect of orientation angle on the damping characteristic of the engine mount. Firstly, the damping measurement is performed on the engine mount in the axial position. Dynamic driving point stiffness is measured. Secondly, the analysis is extended to measure and analyze the frequency dependent stiffness and loss factor at different orientation for the engine mount. The results showed that the stiffness of the engine mount decreases when the engine mount is shifted from vertical to horizontal position. The same observation was also made for the natural frequency of the system. The frequency dependency of the stiffness and loss factor are also shown in the analysis. The measured frequency dependent stiffness and loss factors are then used to reproduce the frequency response function.

The influences of different hybrid fibers (steel fibers add polyvinyl-alcohol fibers) mixture rates for reactive power concrete's (RPC) dynamic mechanical behavior after high temperature burnt was investigated by the Split Hopkinson pressure bar (SHPB) device. A plumbic pulse shaper technique was applied in the experiment, PVDF stress gauge was used to monitor the stress uniformity state within the specimen. The strain rate was between 75~85s-1, base on the stressstrain curves and dynamic modes of concrete specimen, the hybrid fiber effect on the dynamic properties was determined. The results show, dynamic compression strength of specimens which mixed with steel fibers (1.0%,1.5%,2.0% vol. rate) and 0.1% PVA fibers is higher than normal reactive powder concrete (NRPC), but the toughness improves unconspicuous; while strength of the one which has both steel fiber (1.0%,1.5%,2.0% vol. rate) and 0.2%PVA fiber declines than NRPC but the toughness improves and the plastic behaviors strengthened, stress-strain curve has evident rising and plate portions. It can be deduced that the concrete with mixed two kinds of fibers has improved dynamic mechanical properties after high temperature burnt. By compounding previous literature results, the mechanism of the experimental results can be explained.

It is important to ensure the safe and reliable use of massive engineering structures such as offshore platforms, including all aspects of safety and design code compliance. Although routine inspection is an integral part of the safety protocol in operating and maintaining these structures, regular assessment of the effectiveness and efficiency of existing safety evaluation methods is clearly desired in view of emerging technologies for structural health monitoring of engineering structures. The recent advancement in plastic optical fibre (POF) materials and processing render POF sensors an attractive alternative to glass-based optical fibre sensors as they offer much greater being flexibility, high resistance to fracture and hence the ease in their handling and installation. In this paper, some preliminary results demonstrating the use of plastic optical fibre sensors for damage detection and structural health monitoring for offshore and marine-related applications will be summarized. In this study, POF will be used for crack detection in tubular steel specimens in conjunction with a high-resolution photon-counting optical time-domain reflectrometry (v-OTDR). Although the use of OTDR technique is an established method in the telecommunication industry, this study is new in that it is now possible, with the availability of v-OTDR and graded-index perfluorinated POF, to detect and locate the crack position in the host structure to within 10 cm accuracy or better. It will also be shown that this technique could readily be configured to monitor crack growth in steel tubular members.

Lamb wave has a great potential for structural health monitoring of large area structures due to its long range propagation. The piezo array configurations and array pitch for selective mode excitation are first studied with 2D FE models in a composite plate. A single PZT actuator bonded on the top surface of the laminate in unimorph configuration excites both symmetric mode (S₀) and anti-symmetric mode (A₀). The A₀ mode is predominant and four times stronger than the S₀ mode. The second configuration is a bimorph where the PZT actuators are bonded on either side of the laminate. The in-phase excitation of PZT actuators suppress the A₀ mode and excite only the S₀ mode, while the out-of-phase excitation eliminates the S₀ mode and launches the A₀ mode in the laminate. The third configuration is the unimorph array configuration where PZT actuators are bonded on the top surface of the laminate. By keeping the array pitch equal to half wavelength of the S₀ mode, the S₀ mode gets suppressed by twelve times. The FE results are checked with experiments.

The interaction between Lamb wave and damage will modify the response wave signal from which information related to damage can be extracted for automated damage detection. However, the interpretation of the response wave signal is not easy due to the complex nature of the wave-damage interaction. This paper discusses a damage detection algorithm based on wave signal demodulation and artificial neural networks (ANNs). The response wave signal is considered as a low-frequency signal modulated by a high-frequency carrier signal. After baseline subtraction, frequency domain convolution and filtering, the original signal is demodulated and transformed into a new simplified signal related to the energy change due to damage. Subsequently feature extraction is carried out by finding the local maxima in the new signal and the obtained peak values and locations are used as inputs into the ANNs for damage characterization. The validity of this damage detection algorithm is then verified using a finite element (FE) model of a composite laminate with notch defects. The response wave signals of different notch depths and locations are acquired from the simulations and used as the training and testing samples. Finally the assessment of the network's accuracy and generalization ability is performed and the result is satisfactory.

In this study, propagation of acoustic wave through a periodic structure has been analyzed. Such a periodic structure has been found to attenuate sound significantly in certain frequency bands, and therefore it can be used as a frequency filter and sound barrier. Experiments were performed to measure the sound attenuation by the periodic structure made of acrylic cylinders. The experimental results were compared with a simulation study using the finite element method, and they are in good agreement. The benefit of such structure is that it is light weight compared to the solid barriers, and it can be tailored according to the frequency of the sound source to be attenuated.

Recent progresses of smart composite material in our ongoing research are presented in this paper. In recent years, shape memory polymers (SMPs) and electroactive polymers (EAPs) attract more and more attention in the world. In our researching work, different kinds of reinforcement are embedded into SMPs and EAPs to form smart composite materials, aiming to improve the properties or strengthen the materials. Based on the unique properties of SMP based smart composite materials, primary application in the deployable morphing wing are also studied, which provide meaningful guidance for further researching works in this area.

Arbitrary free energy functions, as is proposed by Zhao and Suo, can be applied to analyze the electromechanical stability of the dielectric elastomer. To study the electromechanical stability of mechanical force field placed on dielectric elastomer, variable free energy functions are applied to analyze the mechanical performance of dielectric elastomer. The relation among critical nominal electric field, critical real electric field, nominal stress and mechanical force field is derived, which agrees well with the experimental results. Such a result is capable of understanding better the stability conditions of dielectric elastomers and furthermore guiding the design and manufacture of sensors and actuators based on dielectric elastomers.

We developed a novel technique for bolt tightening control by utilizing SrAl2O4:Eu (SAOE) paint film to detect axial force generated during bolt tightening. Conventionally, torque method is prevalently used for bolt tightening control. The major problem of this method which indirectly controls the axial force in bolted joints is that only a small proportion of the torque actually contributes to the bolt extension. It is the axial force due to such an extension that fastens the bolted joints. Therefore, it is urgently necessary to directly measure the axial force in order to realize a smart tightening control. Considering the extension of bolt during tightening can induce elastico-luminescence of SAOE if it is painted on the bolt or washer, we have painted SAOE/polymer film on the washer and consequently measured elastico-luminescence of SAOE film while tightening the bolt under various conditions. In the present work, we also demonstrated the correlation between the elastico-luminescence intensity and tightening conditions including tightening speed and strain as well as axial force.

As a class of semi-crystallized polymers, shape memory polymers (SMPs) exhibit significant viscoelastic characteristics in the vicinity of the glass transition temperature Tg, which should affect their shape storage and recovery functionality. However, until now isothermal and elastic assumptions are commonly considered when studying the thermomechanical properties of this class of functionalized materials. This papers aims to present some experimental results about the viscoelastic characteristics of SMPs. Systematic thermomechanical experiments were performed on shape-memory polyurethane under uniaxial tensile loading, which includes the frozen/recovery tests under different constraint conditions, stress-strain cycles and stress relaxation at different temperatures. Based on the testing results, the viscoelastic characteristics effect on the shape frozen and recovery responses of SMPs are discussed, which is of importance in proposing suitable thermo-viscoelastic constitutions about this type of functional materials.

The effect of a dual piezoelectric actuators ultrasonic linear motor is studied in this research. The two piezoelectric actuators are bonded with a linear elastic stator. The stator generates the traveling wave when the actuators are subjected to the harmonic excitations. Vibration characteristics of the linear stator are determined by using the finite element analysis, i.e., modal, harmonic and transient responses. In the experiment, the motor characteristics are tested, i.e., the maximum velocity, operating frequency and applied voltage. In addition, the relationship between the pre-load and velocity of the motor is reported. The result shows that the maximum velocity of the motor occurs at a specific per-load. The comparison of the operating frequency and harmonic response shows well agreement between the finite element and experimental results.