In order to use a low flammability magnesium alloy as structural components, very high cycle fatigue property of this alloy (AMCa602) was investigated in rotating bending. As results, it was found that some specimens failed from surface inclusions and their fatigue lives were lower in comparison with those of the specimens without surface inclusions. And, the fracture surfaces of this alloy revealed very rough in the usual life region, whereas a smooth area was observed on the fracture surface of specimens failed from surface inclusions in gigacycle regime. A stress intensity factor range at the tip of the smooth area tended to a definite value so that the fracture mechanism of this alloy was governed by a concept of ΔK.

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The axial fatigue tests with constant load and stress rations of -1.0 and 0.1 were conducted in order to investigate the effects of the laser peening (LP) treatment on the fatigue strength and the fatigue crack behaviors in the rolled aluminum alloy A7050 for aircraft structures. The LP treatment was effective for fatigue strength improvement in the fatigue lives before 2〜3×10^6 cycles, but the treatment reduced the strength after the cycles at the both stress ratio conditions. Fatigue cracks initiated at the surface on the higher stress amplitude levels, but the cracks initiated in the internal positions on the lower stress levels. Next, the axial fatigue tests with repeated two-step loading and stress rations of -1.0 were conducted in order to investigate the effects of the LP treatment on the fatigue strength and the fatigue crack behaviors. In the case of LP treated materials, it is found that the high stress has effect on the fatigue life but the low stress has little effect on the fatigue life.

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In order to improve the high cycle rotating bending fatigue property of Ti-6Al-4V Titanium alloy, laser peening without coating and shot peening with zirconia shot were applied. As the result of investigating the relation between fatigue property, surface roughness and residual stress, it proposed that fatigue life property was improved by giving the mild compressive residual stress which was C-Type distribution without surface roughness increasing.

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Bulk amorphous alloys have various kinds of superior properties such as high strength, excellent wear resistance and excellent corrosion resistance. In order to investigate the fatigue properties of Zr-base amorphous alloy in very high cycle regime, rotating bending fatigue tests were performed for 3 types of Zr_<55>Al_<10>Ni_5Cu_<30> sample. As results, S-N curve of Zr-base bulk amorphous alloy indicated clear fatigue limit and Zr-base bulk amorphous alloy has failed in the surface fracture mode even in very high cycle regime. Moreover, the statistical aspect on the fatigue property was analyzed as P-S-N characteristics by the method based on the JSMS standard.

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In recent studies of very high cycle fatigue, a unique phenomenon of nano-structural refinement has been observed beneath fracture surfaces due to a large number of repeating contacts of themselves over 10^7 cycles. Focusing on this phenomenon, this study proposed a new surface treatment named Cyclic Press Method to refine metal surface without profound plastic deformation. A low cyclic compressive load was given to the surface of Ni-Cr-Mo steel (SNCM439) and Al-Si-Cu die-casting alloy (ACD12) for 5×10^7 cycles. After that, the longitudinal section was processed by FIB and was observed with SIM. As a result, the nanocrystalline structure was clearly formed in the surface layer of both materials. The size of nano-grains and the depth of nano-layer were different between two materials; however, the Cyclic Press Method was shown to be effective in nano-structural refinement of metal surface.

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The electro-mechanical fracture problem of a piezoelectric strip containing a T-shaped crack is considered in this study. The problem is solved for a piezoelectric strip that is under electromechanical loadings. The crack faces are supposed to be completely insulated. By using the Fourier transform, the electromechanical problem is reduced to a system of singular integral equations. The singular integral equations are solved numerically. Numerical calculations are carried out, and detailed results are presented to illustrate the influence of the electro-mechanical interaction on the stress and electric displacement intensity factors. From the numerical results, we can find that the normalized stress and electric displacement intensity factors are under the great influence of the geometric parameters.

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The present study is intended to evaluate heat transfer characteristic and strength at elevated temperature of a receiver in which concentrated solar radiation is converted to thermal energy. A flat-plate receiver is considered as an object of the present study, and a small-sized prototype of flat-plate receiver which is compounded of a steel fin and copper tubes is designed and manufactured for trial. Temperature and strain in the receiver subjected to concentrated radiation by use of solar simulator are measured, and time-evolution of temperature and thermal stress in the receiver are examined.

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Since solar energy is nonpolluting and will not be depleted, the development and spread of concentrating solar power technology have been promoting. The study and development of new energies have been also promoting in Miyazaki prefecture. The research project team in faculty of engineering, University of Miyazaki continues to work on study and development of solar energy technologies by making use of Beam-down Solar Concentrator. In the present study, a flat compound plate composed of different kinds of materials is considered in order to examine the heat transfer characteristic and strength at elevated temperature of flat type receiver in which concentrated solar radiation is converted to thermal energy. The analytical development of heat conduction and thermal stresses for the compound plate is treated. Then, effects of materials and thickness on the temperature and thermal stresses in the plate are discussed from the theoretical point of view.

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In this study, we investigate thermal stress problem of a hollow circular truncated cone, which is simulated such as a body of space-plane and a tapered tube. First, the coordinate system and element for the analytical model is defined, and heat condition problem for the analytical model is considered. By applying the defined element, the analytical solution of temperature fields in a hollow circular truncated cone is obtained easily using analytical solutions of temperature field for cylindrical coordinate system. Example calculations for the temperature fields are carried out. Also, an analytical approach for thennoelastic stress analysis using the defined element and coordinate system in this study is discussed.

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The electromechanical fracture problem of a piezoelectric strip containing two coplanar cracks are considered in this study. The problem is solved for a piezoelectric strip that is under a uniform mechanical load far away from the crack region. By using the Fourier transform, the problem is reduced to a system of singular integral equations. The singular integral equations are solved by using the Gauss-Jacobi integration formula. Numerical calculations are carried out, and detailed results are presented to illustrate the influence of the parameters of indicating the crack lengths and the crack locations on the stress intensity factors. From the numerical results, we can find that the normalized intensity factor are the great influence of the geometric parameters.

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Stresses around two equal collinear cracks in an infinite elastic medium are evaluated based on the linearized couple-stress theory under uniform tension normal to the cracks. Fourier transformations are used to reduce the boundary conditions with respect to the cracks to dual integral equations. In order to solve these equations, the displacement and the rotation at the cracks are expanded through a series of functions that are zero-valued outside the cracks. The unknown coefficients in each series are solved in order to satisfy the boundary conditions inside the cracks using the Schmidt method. The stresses are expressed in terms of infinite integrals, and the stress intensity factors can be determined using the characteristics of the integrands for an infinite value of the variable of integration. Numerical calculations are carried out for selected crack configurations, and the effect of the couple-stresses on the stress intensity factors is revealed.

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Foam-filled thin-wall structures exhibit significant advantage in light weight and high energy absorption. Axial compression wes done to investigate the crash behavior of the empty and foam-filled cylindrical tubes. Non-linear finite element analyses were carried out to simulate the axial compression. The energy absorption capacities of the filled tubes were compared with the empty cylindrical tubes. The results showed that the energy absorption capability of foam-filled tube is higher than that of the combined effect of the empty tube and the foam alone. The reason is that the foam prevents the cylindrical tube from a natural deformation.

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In this paper, the peak load and the crashing behavior of this circular truncated cone subjected to axial compression is studied by using finite element method. The influence of the impact velocity and the mass investigated. In order to evaluate the peak load and crushing behavior due to the collision condition, spring-mass model is used.

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In this paper, the crushing behavior of hexagonal honeycomb structure with finite width subjected to in-plane compressive loading is studied by using finite element method. It is found that stress-strain curves are classified roughly into two types. They are influenced by ratio of thickness of cell wall, ratio of the work hardening, and state of defects. In addition, for a honeycomb structure in which defects assembles in a row, the peak stress can be predicted by using a model without defect. For a model with defect, the energy absorption characteristic doesn't fall off very much.

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The "Sirasu Balloon(SB)" has micro glassy spherical shell body which manufactured from volcanic pumice tuff by heating it rapidly at about 1300K. The mechanical and thermal properties of polymer composites reinforced with glassy micro balloons are investigated in temperature conditions. The matrix is epoxy resin and its dispersion is micro size of glassy spherical hollow shells of SB. Developed composites are a kind of micro porous materials with low density. From the experimental results, mechanical behaviors of the composites were clarified, and the effects of material properties and configurations on the mechanical properties of composites were discussed from the viewpoint of micromechanical study. Using a model of micro porous materials and setting property of each material, numerical calculations were performed by FEM analysis. Analytical results for the mechanical behavior made a good agreement with experimental results of heat transfer of the composites and thermal conductivity of the composites was estimated by using the model.

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A study regarding to a development of the versatile numerical analysis program applicable to general 3-dimensional elastic problems based on the Body Force Method was examined. In the present analysis, a planner triangular surface element is chosen as the boundary element. In order to overcome the difficulty arising in a boundary integral of the fundamental solution with singular functions, a polar transform scheme is adopted. Through numerical examples, it was found that the present method is practical and convenient to analyze a stress concentration problem gregarding to a spherical cavity in an infinite solid.

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In this paper, two-dimensional electroelastic analyses are performed for a piezoelectric materials bonded to the surface of a semi-infinite plate. General solutions are provided in terms of complex functions, and several numerical examples are shown by graphical representation. The effect of stress relaxation by piezoelectric materials is discussed.

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Doppler effects are discussed for dispersive deflection waves in 1D beam and 2D plate. Exact dynamic analysis is carried out for the beam and plate with a moving edge. The frequency shift, reflection angle and amplitude are derived exactly. The Doppler effects for the dispersive wave are different from those for the non-dispersive elastic/electromagnetic wave, but their approximate forms for a small Mach number are identical. In the case of plane wave, the reflection angle for the dispersive wave does not exceed π/2, but that for the non-dispersive wave exceeds. The reflected wave with this critical angle runs on the moving edge as if the evanescent wave does.

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With the aim of achieving stable operation of circular saws, this study finds the solution for the optimization problem of choosing a set of parameters for tensioning in a rotating circular saw that is subjected to both a local temperature distribution arising from the thermal load caused by the blade-workpiece friction and the in-plane plastic strain introduced by tensioning over a single annular domain. The solution for in-plane forces is obtained on the basis of plate bending theory, and modal analysis for the out-of-plane behavior affected by the in-plane forces is performed. Numerical calculations are performed to investigate the effects of tensioning on the natural frequencies. The optimization problem to maximize, with respect to the intensity, location, and width of tensioning, the natural frequency of the most critical mode is solved by use of a genetic algorithm, and the optimal parameters of tensioning are determined at computational costs that are considerably lower than those of 100% inspection.

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Steel conveying rollers used in a heat treating furnace must have been changed very frequently because high temperate of a furnace induces the wear on the roller's surface ceramics coating in short period. This paper deals with a roller structure consisting of ceramics sleeve and two steel shafts connecting to the sleeve by shrink fitting because the ceramics has high temperature resistance and high corrosion resistance. It should be noted that in this structure only low shrink fitting ratio can be used because of the brittleness of the ceramics. However it has been reported that the shaft may come out from the sleeve during rotation because of the low shrink fitting ratio. In this study, therefore, two types of simulation are performed by FEM. One model assumes the applied load to the shaft varies along the circumferential direction of the shaft at the interval angle θ=30°, and the other model assumes at the interval angle θ=6°.

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This paper discusses a control problem of a transient thermal stress in a smart multi-layer composite disk consisting of a transversely isotropic structural layer onto which piezoelectric layers of crystal 6mm are perfectly bonded. The first piezoelectric layer serves as a sensor and the other piezoelectric layers serve as an actuator. It is assumed that a number of electrodes are arranged concentrically on the upper surface of each actuator layer. When an unknown heating temperature distribution acts on the bottom surface of the composite disk, a transient electric potential distribution is considered to be measured on the upper surface of the sensor layer. The unknown heating temperature can be inferred from the measured electric potential. Then, voltages applied to all electrodes can be determined by optimization so that the maximum transient thermal stress in the structural layer is minimized subject to constrains on the stresses in the piezoelectric layers. Finally, numerical results are shown in a table.

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This paper discusses a displacement control problem in a multi-layer composite disk consisting of a transversely isotropic structural layer onto which piezoelectric layers of crystal class 6mm are perfectly bonded. It is considered that some electrodes are arranged concentrically on the top surface of each piezoelectric layer. When a stationary heating temperature distribution acts on the bottom surface of the composite disk, the thermally induced elastic displacement on the structural layer surface can be controlled by applying appropriate voltages to the electrodes. In order to maximize the function of displacement control, an optimum design of the electrode arrangements is performed. The applied voltages are determined by using the quasi-Newton method based on the BFGS updating formula, whereas the electrode arrangements are determined by employing the particle swarm optimization (PSO). Numerical calculations have been carried out for a composite disk consisting of a CFRP layer and cadmium selenide layers .Obtained numerical results are shown in tabular and graphical forms.

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Porous media with particles are an attractive material system for multi-functional composite materials. The random geometry like as real media is analyzed with the objective of reproducing it numerically. For efficient numerical calculation, micromechanics model of the porous composite is proposed for predicting the anisotropic mechanical properties of porous materials. Random distribution of ellipsoidal voids and particles is generated in the periodical unit cell region. Mechanical properties particle-reinforced porous materials are evaluated using the model.

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Engineering plastics provide superior performance to ordinary plastics for wide range of the use. For polymer materials, dynamic stress and strain rate may be major factors to be considered when the strength is evaluated. Recently, high speed tensile test is being recognized as a standard testing method to confirm the strength under dynamic loads. In this study, therefore, high speed tensile test is analyzed by the finite element method; then, the maximum dynamic stress and strain rate are discussed with varying the tensile speed and maximum forced displacement. It is found that the strain rate is controlled by the tensile speed alone independent of the magnitude of the forced displacement.

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This paper is concerned with the theoretical treatment of transient thermoelastic problems involving functionally graded cylindrical panel with piecewise power law due to nonuniform heat supply. The thermal and thermoelastic constants of each layer are expressed as power functions of the radial coordinate, and their values continue on the interfaces. We obtain the exact solutions for the two-dimensional temperature change in a transient state, and thermoelastic response. Some numerical results for the temperature change, the displacement and the stress distributions are shown in figures.

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Heat-ray absorbing sheet glasses can decrease electric energy used for air-conditioning by control the incoming heat-ray through windows into the rooms. On the other hand, the glasses increase the temperature and sometimes yield heat cracks by thermal stresses. It is important to know the state of thermal stresses accurately in order to develop heat-ray absorbing sheet glasses with higher performance and without heat cracks. A conventional design manual at field site treats the steady state and the thermal boundary condition that all heat-ray are absorbed at glass surface. In this paper, it is assumed that the heat-ray is absorbed over all the plate thickness. The idea of the absorptibity per unit length is introduced. The modeling can explain well that the total absorptivity depends on the plate thickness. The temperature and the thermal stresses are compared with ones calculated by the conventional design manual at field site.

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Thermoelastic problems in piezoelectric materials of class 6mm can be theoretically analyzed by employing a potential function method. The governing equations of the potential functions include coefficients which are solutions to two characteristic equations derived from the stress equation of equilibrium and the equation of electrostatics. For the case of previous studies, piezoelectric materials were selected so that the solutions were given in real numbers. Since there are a few such materials, the extension has been required for a thermoeasltic problem in a piezoelectric material when solutions to two characteristic equations are expressed in comlex numbers. The corresponding piezoelectric materials are PZT cermics. In this paper, a thermoelastic problem in a two layer composite circular disk consisting of a CFRP structural layer onto which a PZT ceramic layer of crystal class 6mm is perfectly bonded. It is then assumed that a number of electrodes are concentrically arranged on the PZT cermic layer. When a heating temperature distribution acts on the structural layer surface, the maximum thermal stress in the structural layer can be suppressed by applying appropriate voltages to the electrodes. The applied voltages are determined by solving a linear programming problem. Obtained numerical results are shown in tabular and graphical forms.

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3D IC packaging has been receiving increased attention for system performance enhancements without relying on further device scaling. Recently, 2.5D IC packaging has been proposed as a more realistic approach, in the view point of supply chain, design rules, and yield. However, 2.5D & 3D IC packaging have technical challenges, such as in the thermal and mechanical point of view. In this paper, the trend and technical challenges of 2.5D & 3D IC packaging are described.

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Numerical methods such as the finite element method (FEM) have been used to evaluate the reliability of electronic packages. However, it is difficult to assure the accuracy of numerical analyses of electronic packages, which require nonlinear analyses. In this study, we evaluated the thermal strain of a test chip for three-dimensional stacked integrated circuits (3D SIC) with both measurement and numerical analyses. First, the distribution of the thermal strain on the cross-section of a test chip was measured using scanning electron microscope (SEM) and the digital image correlation method (DICM [1]). Then, the distribution of strain of the test chip was also analyzed by the FEM considering the viscoelastic material properties of underfill (UF) resin [2] measured with the stress relaxation test and the elastic-plastic material properties of components measured with nano-indentation tests [3]. We improved the accuracy of the nonlinear finite elemant analysis using strain measurements made by the SEM-DICM.

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Microscopic strain localization in copper (Cu) micro-interconnection, which connects through-hole electrodes in a three-dimensional chip stacking LSI, is examined by using the crystal plasticity finite element method analysis. Analytical models composed of 20 and 1900 grains are prepared on the basis of a nucleation and growth model. Strain localization appears in the models owing to the deformation constraint among grains. Stain concentration in the 1900-grains model is larger than that of the 20-grains model.

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The crack generation of Si and the yielding of TSV(Through Silicon Via) in 3D System in Package will be concerned in the cases of reflow process. In this study, we discussed on the thermal stresses of Si and TSV in 3D SiP under the reflow process of electronics devices. ADVENTURECluster which is parallel computing simulator based on finite element method is adopted to simulate thermal stresses. The stresses of the TSV were higher than yielding stress of copper. Maximum principal stress of edge part of Si was estimated to be around 500MPa. This stress was close to the bending strength of silicon and edge part of silicon was singular stress field.

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Equivalent material properties of thermal conductivity, Young's modulus, Shear modulus and Poisson's ratio for micro bump layers were estimated by FEM simulation. The chip connections were built by copper and Sn-Ag-Cu solder and the equivalent material properties showed anisotropy depend on the fine structure of materials in micro bump layer. Response surface of these equivalent material properties were made by using plan of experiment method. Equivalent material properties that are difficult to be derived by the mixing rule can be efficiently derived by using the response surface.

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In order to evaluate the thermal fatigue of the Sn-3.0Ag-0.5Cu solder joint on the electronic substrate, elastic-plastic creep analysis in a solder joints was conducted using the finite element method. It was shown clearly that the temperature range and the average temperature influenced the thermal crack initiation lifetime. The thermal load history of solder joints was presumed. The approximation process of the load history and residual life of solder joints was discussed.

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Sub-crystal grain scale adhesion strength of the interface between Cu line and insulation layer in LSI interconnect systems was evaluated by performing fracture test with 100nm-scale cylindrical specimens fabricated by focused ion beam. Furthermore, the correlation between interface adhesion strength and crystal orientation was investigated by observing the electron backscattering diffraction image at the footprint of the specimen after the fracture test. As a result, the evaluated adhesion strength strongly depends on the crystal orientation of Cu surface facing to the interface. This result suggests that the scatter of the local adhesion strength is caused by the microstructure of Cu line.

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For a brick-shape specimen with grain-scale dimensions on a damascene wiring, a fracture test was performed by a nanoindenter inside the SEM to evaluate the adhesion strength of the interface Cu/SiN. The copper grain distribution on the specimen footprint was observed by EBSD analysis. The correlation of the adhesion strength and multi-grain structure in the specimen footprint was evaluated. As the result, it was found that adhesion strength was significantly affected by the copper multi-grain structure.

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Local mechanical properties of a copper line were mapped by doing nanoindentation test inside scanning electron microscope. The evaluated reduced modulus and the hardness had a large scatter without the clear trend related to the geometry of copper line. The crystal orientation distribution of the copper was measured to investigate the correlation between the fluctuation of local mechanical properties and the microstructure. Considering the statistical trend, the reduced modulus looked insensitive to the microstructure around the indents and the hardness looked sensitive. The average of the hardness obtained by indents nearby the junction of boundaries was higher than the average obtained by indents far from boundaries, where the boundary means either a twin boundary or a grain boundary. In addition, a larger scatter was observed in the hardness nearby the junction than of the hardness far from boundaries.

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In this paper, the effect of crystal anisotropy on the evaluation of bonding energy of interface between Cu metal line and insulation layer in LSI was surveyed. Experiment was performed with specimens made of the insulation layer left on the Cu line surface. Dimensions of the specimen were 300x300x480 nm, which was as large as the size of grains. A finite element model of specimen and Cu line was subjected to the elastic crack extension simulation, where Cu crystal was rotated around horizontal axis and vertical axis ranging from 0 to 90 degrees to evaluate the bonding energy. As a result, a range of bonding energy from 2.22 J/m^2 to 2.64 J/m^2 was obtained. On the other hand, in the case of evaluation where Cu was modeled as an isotropic material, 2.32 J/m^2 was obtained. Since much larger range of data scatter was observed in the experiment, it was suggested that anisotropy of plastic deformation should be taken into account to properly explain the fracture behavior of Cu/insulation layer interface.

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Crystal orientation of Cu has a significant impact on the local interface adhesion strength between Cu/SiN layers in micro wirings in LSI. Using a finite element model with crystal plasticity, crystal orientation dependence of the interfacial strength was evaluated. For the finite element model, three different Cu crystal orientations such as (100), (110), and (111) facing to the interface were surveyed and also the effect of angle θ=between load and slip directions was evaluated for the cases of 0° and 90°. For the same crystal orientation, the energy release rate G obtained with θ= 90° was higher than 0° because of the higher resistance against slip. For (100), G were 2.02 J/m^2 and 2.02 J/m^2. For (110), G were 1.8 J/m^2 and 2.1 J/m^2. However, G values were 0.06 J/m^2 and 0.22 J/m^2 for (111), which were far smaller than the other cases. Consequently, it was considered that the G value depends mainly on how easily Cu crystal slips beneath the interface. It was demonstrated that the evaluated interface adhesion strength is dependent ofthe crystal orientation for the micro-scale Cu metallization systems in LSI.

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Semiconductor devices are getting smaller and smaller, which lead to some problems such as cross-talk and signal delay. Therefore, the low-dielectric insulating layer is necessary for semiconductor devices. To overcome this problem, we propose a nano-structured insulating layer. Nano-sized structure is orderly aligned, which are made by dynamic oblique deposition (DOD). The size and structure of structure can be controlled in DOD method and, thus, the amounts of air space in insulating layer are able to be controlled. The objective of this study is to present the way to measure Elastic modulus about multilayer thin films, and to measure elastic modulus of nano-structured insulating layer. Multilayer structure is modeled as serial springs, so we obtain the elastic modulus of nano-structured insulating layer from nano-indentation results. The results show that elastic modulus of nano-structured insulating layer is mainly influenced by the volume density of nano-structures.

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A new highly sensitive strain measurement method has been developed by applying the change of the electronic conductivity of CNTs. In order to design a new sensor using CNT, it is very important to control the shape of the MWCNTs. Thus, the method for controlling the shape of the MWCNTs was developed by applying a chemical vapor deposition (CVD) method. It was found the shape of the grown MWCNT can be controlled by changing the average thickness of the deposited iron particles and the deposition temperature. The maximum strain sensitivity obtained under the application of uniaxial strain was about 10%/1000-μstain (gauge factor: 100). Two-dimensional strain sensor has been successfully developed by applying thin-film processing on a silicon wafer.

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Non-contact stress evaluation is required for nano-scale devices related to LSI and MEMS to improve their characteristics and reliability. Raman spectroscopy is known to measure surface stress of silicon without contacts and damages, but it cannot be applied to silicon-oxide(Si0_x) film that is commonly used as a passivation layer in silicon MEMS. We have proposed the stress measurement method for SiO_x, films using cathodoluminescence (CL) spectroscopy. However the CL stress measurement has a potential damaging the SiO_x, because electron beam (EB) irradiation is used for excitation of a specimen. To investigate the damage, we conducted Raman spectroscopic analysis and transmission electron microscope (TEM) observation. From Raman spectroscopic analysis, it found that stress distribution was changed at around EB irradiation spots. This change was probably caused by a structural change in SiO_x film or some damage at SiO_x/Si interface by the irradiation. And the TEM observation identified that EB irradiation produced silicon nanocrystals in SiO_x film. To measure the stress in SiO_x film using CL spectroscopy without any damages, EB irradiation condition without silicon nanocrystals generation must be specified

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We conducted uni-axial tensile testing using electrostatic-force grip on single crystal silicon thin film of <111> direction. The specimens were fabricated on (110) SOI wafer (length: 120 μm, width: 5 μm, thickness: 5 μgm) and went through 3 different conditions of patterning process composed of Bosch process and treatment of surface residue. As a result, improvement of surface morphology brought increase of average tensile strength from 1.9 GPa to 3.6 GPa. SEM observation of fractured specimens shows that, regardless of processing conditions, the relationship between the tensile strength and the size of damage on the top corners can be expressed with a common equation. This result suggests that the damage on the top corners was dominant for the fracture of this specimen.

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In this article, the influences of specimen size and deformation-mode on the fracture strength of single-crystal silicon (SCS) micro-beam structures are described. We have designed and developed a new materials test device that is able to apply pure torsion, uniaxial-tension, bending, torsion-bending-combined, and torsion-tension-combined deformations to a micro-scale beam specimen. The specimen made of SCS consists of a SCS plate supported by two SCS micro-beams, and a frame, and was fabricated by deep reactive ion etching (DRIE) with the same fabrication recipe. All the SCS specimens tested in those deformation-modes were fractured in a brittle manner at a laboratory temperature. The fractured strength was calculated assuming that all the specimens had an ideal flat surface, and the data were arranged using two-parameter Weibull distribution function. Both the specimen size and deformation-mode dependencies were apparently found. To estimate the "true" strength, finite element analyses (FEAs) using the models that included scalloping sidewalls were carried out. The revised strength data that were estimated by multiplying stress concentration factors into the original data suggested that no deformation-mode dependency on strength existed.

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In this paper, fatigue lifetime prediction models based on time dependent and cycle dependent mechanisms were compared. Their theoretical backgrounds are stress corrosion cracking (SCC) for the former model and dislocation for the latter. The models were fitted to the experimental results with single crystal silicon specimen carried out at different frequencies. The stress-lifetime curves based on SCC theory appeared in two groups of respective testing frequencies. On the other hand, the curves based on dislocation theory were almost identical regardless of frequency. These results suggest that dislocation is more likely mechanism for fatigue rather than SCC.

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The relationship between the wrinkle formation with aging and the strains by daily motion is investigated by measuring the strains of the facial skin surface for several human subjects. A digital image correlation technique based on a stereovision is used for measuring the strains of the facial skin. Results of the strain measurement show that the strains tend to be concentrated in the common place of facial skin for all human subjects. On the other hand, the different distributions of the principal direction are observed for different aged human subjects. It is also observed that the relationship between the strain and the skin surface morphology at the corner of the eye is different from that under the eye. Results of the strain measurement for various skin conditions show that the strain occurs locally under dry skin conditions whereas strain occurs uniformly under moisture skin conditions. Therefore, it is expected that skin surface morphology can be improved by moisture retention.

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Three dimensional measurement of displacement with Digital Image Correlation (DIC) method was investigated. Stereo camera method using two CCD cameras was applied for three dimensional measurement. In this method, movement of the images of two cameras was measured for parallel translation of the base plate in the preliminary test and Look-Up Table showing the relation between image movement and three dimensional movement of the base plate was obtained from the preliminary test. Linear equations were also considered to express the LUT between the movement of the images and the actual translation of the base plate and three dimensional displacement of the base plate was obtained by solving the equations inversely. In this method, we used the equations from the preliminary calibration test, we can estimate three dimensional displacement of the object accurately.

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It is well known that the tensile strength of knotted strings is weaker than the material strength of the strings. However, the strength of the knotted strings has not fully understood from the scientific viewpoint. In the present study, digital image correlation method is applied to examine the strength and characteristics of knots, especially overhand knot and figure-of-eight knot. The result shows that the shearing strain at the shoulder part of the overhand knot is larger than that of the figure-of-eight knot. This result is in good agreement with the result of tensile tests, which shows that the fracture stress of the overhand knot is lower than that of the figure-of-eight knot.

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Young's modulus and Poisson's ratio of metal thin films were calculated by applying the digital image correlation technique that can measure the whole field displacement without contact. First, the program which can measure sub-pixel displacement was created and the accuracy of this program was checked using a precision stage. Next, the tension tests of aluminum alloy and steel were performed to obtain the displacement in tension. Elastic moduli of these materials were calculated based on the displacement measured from this method and the validity was confirmed by comparing these results with results of a strain rosette. Finally, the elastic moduli of electrodeposited copper and nickel film were calculated in the same manner. It was cleared that Young's modulus of metal films was quite small compared with bulk materials.

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