This paper presents a new inverse analysis method based on wavelet transform theory. For solving inverse problems, it is important to use a priori information efficiently. This method enables to use the local frequency-characteristic of estimates as a priori information which has not be used in conventional methods. Firstly, the estimates are divided into some components by using wavelet transform algorithm. Each component has different frequency-characteristic/resolution. Secondly, according to a priori information, elements in the component are manipulated. Thirdly, those components are identified from low to high frequency-characteristic/resolution component sequentially. Finally, the estimates are reconstructed from those identified components by using inverse wavelet transform algorithm. A numerical simulation is performed to demonstrate the validity and usefulness of the proposed technique.

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Delamination identification is very important for structural health monitoring of composite laminated structures. In the present study, a two-step delamination identification method using resonant and anti-resonant frequency changes is proposed. The present method can identify the location of delamination and the size nondestructively. As a preparation for delamination identification of a CFRP laminated beam, the beam is divided into two domains. At the first step, the delaminated domain is identified using the anti-resonant frequency changes. At the second step, the delamination location and the size are identified in the delaminated domain using the resonant frequency changes. Delamination identifications of CFRP cantilever beams are conducted using both FEM analysis data and experimental data. As a result, effectiveness of the present method is shown.

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Fractal branch and bound method has developed by authors for optimization of stacking sequences to maximize buckling load of composite structures. The method demands an approximation of a design space with a response surface of quadratic polynomials for trimming fractal branches of stacking sequences. The approximation of the objective function with quadratic polynomials has been confirmed for the buckling load maximizations using lamination parameters as predictors. Although maximizations of flutter limits of composite panels for supersonic flow has already shown by several researchers, it is not clarified that the design space of the supersonic flutter limit can be approximated with quadratic polynomials. The present paper describes the approximations using quadratic polynomials with lamination parameters as predictors are performed to investigate the effectiveness of the method for the supersonic panel flutter of composite laminates. As a result, the method is successfully applied, and the practical optimal stacking sequence is obtained using modified response surfaces.

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Thermal barrier coating (TBC) is used to protect hot parts of gas turbine from a high-temperature environment. Recently, TBC delamination damage was also reported in some Japanese electric power plants. It is important to establish a TBC delamination evaluation-method for preventing such damage. It is known that the delamination is due to a reduction of interface cohesion between coating layer and substrate, and then the reduction is caused by a formation of thermally growth oxidation (TGO) layer at the interface. Thus, it is necessary to understand TGO layer growth behaviour and the growth mechanism. The aim of this study is to examine effect of an aging temperature and an aging time on TGO layer growth under various aging temperature conditions, and then to discuss a TGO growth mechanism through SEM observation of a cross section of aged TBC specimen. As some results obtained, TG0 layer was not formed at the aged temperature below 973 K. In aging temperature range between 1 073 K and 1 173 K, Al₂O₃ as TGO layer was formed at the interface between top coating and bond coating layer. At aging temperature 1 273 K, (Co, Cr, Al) complex oxidation in addition to Al₂O₃ at the interface was observed. It was shown from TGO growth curve that the growth exponent n was 0.3 in aging temperature range 1 073 K to 1 173 K, and then 0.1 at 1 273 K in contrast with 0.5 for a metal oxidation process. Then, TGO layer grew by diffusion of oxidizing species on grain boundary in coating layer. Additionally, the reason that the growth exponent at 1 273 K was reduced was due to what the complex oxidation layer was acted as barrier to the species diffusion.

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It is difficult to analyze bending properties of Filament Winding Cylinders (FW Cylinders) because fibers are complicatedly wound and FW Cylinders are not composed of laminae. In this study, the method to evaluate the flexural rigidities of FW Cylinders with several winding angles was proposed by using Finite Element Method (FEM), and the results of FEM analyses were compared with results of 3-point bending tests. As a result, both results of FEM analyses and experiments were quantitatively agreed to each other. And it was found that flexural rigidities of FW Cylinders which were made with small winding angles were became large values, but large deformation occurred on the cross-section at central loading point by bending load, especially for thin wall FW Cylinders. Moreover, it was cleared that flexural rigidities were strongly influenced by the thickness of FW Cylinders.

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In order to study impact properties of the honeycomb sandwich panel (hereafter, HSP for brevity), drop weight impact tests were carried out using 4 kinds of HSP at several drop velocities. Where, an aramid was used as cores and its core heights were 22.5 mm and 6.3 mm. Surface boards of HSP were made on the aluminum alloy (A 1 100P) and the fiber reinforced plastic (hereafter, FRP for brevity). Based on the variation of observed deceleration to time of the weight after the impact, absorption energies were calculated. When the energy absorption abilities were compared, HSP with flat plates of the aluminum alloy was superior to that with FRP. This was attributed to the fracture patterns at impact point.

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The onset of cavitation is modeled by introducing a small hole in the particle. The results indicate that the relations between the average normal stress and volume change of the particle are cast into a characteristic single line for all cases in the present investigation. The maximum mean stress appears at the front or the inflection point of the inclination of the shear band, which corresponds to the intersection point of the shear bands. Soft rubber particles promote the clastic deformation, which suggests a higher absorption of the energy and a lower maximum value of mean stress in the polymer. The increase of the macroscopic strain ratio promotes the plastic deformation of polymer and the onset of macroscopic yielding with a lower value of yield stress, whereas the high triaxiality of the macroscopic stress increases the mean stress in the polymer. The effect of heterogeneity of the particles on the maximum mean stress in polymer is remarkably different depending on the applied strain ratio. The increase of the volume fraction of particles promotes the shear band connecting the particles and relaxes the stress concentration, which results the reduction of maximum mean stress in the polymer.

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The optimum process design system for sheet fabrication was developed by combining finite element analysis and discretized optimization algorithms. Generally, material development for sheet fabrication have been carried out for better formability index such as n-value and r-value, etc. However, various factors have influence upon the forming performance and the formability. It can't be said that higher n-value and r-value are not always better for any forming condition. The aim of this system is to assist the decision of material process condition for waking the sheet metal, which has better formability in stamping. In the study, annealing temperature and time are chosen as the process parameters. Formability is evaluated by thickness uniformity of stamped part. The response surface method was applied in order to improve the search efficiency of optimization algorithm. It is demonstrated that the proposed optimum process design system is a useful tool for the design of material process and sheet metal fabrication.

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The rate-dependent inelastic constitutive equation is formulated by extending the elastoplastic constitutive equation so as to retain its mathematical structure and thus reduces to the latter equation at infinitesimal strain rate, whilst the over-stress model, the best-known inelastic constitutive model, has substantially different mathematical structure from the elastoplastic constitutive equation. It belongs to the superposition model pre on the additive decomposition of the inelastic strain rate into the plastic and the creep strain rates. It can describe precisely the rate-dependent inelastic deformation at a wide range of strain rate, whilst the over-stress model cannot predict appropriately the difference of mechanical response due to the rate of deformation, especially inapplicable to the description of deformation at high strain rate.

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The rate-dependent inelastic constitutive equation was formulated by extending the subloading model such that the plastic strain rate is suppressed with the increase of strain rate and incorporating the creep strain rate in the previous article. It retains the mathematical structure of the subloading surface model and thus reduces to the model itself at infinitesimal strain rate. It belongs to the superposition model premising on the additive decomposition of the inelastic strain rate into the plastic and the creep strain rates. It is applied to metals, and its adequacy is verified comparing with various test data at a wide variety of strain rates and temperatures.

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A constitutive model for the description of friction phenomenon is formulated by incorporating the subloading surface concept proposed for the formulation of the unconventional plastic constitutive equation. It describes the nonlinearity of the relationship between the normal and the tangential forces on the contact boundary. Further, it describes the smooth relation of the contact force and the sliding distance, i.e. the smooth elastic-plastic transition and the thus the judgment for the fulfillment of friction condition is not needed, which is required in the conventional friction theory. Thus, a rough numerical calculation with large loading steps is allowed in the present model.

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This paper is concerned with the implicit integration and consistent tangent modulus of a high-temperature constitutive model, in which time-dependent inelastic strain rate consists of the transient part affected by kinematic and isotropic hardenings and the steady part depending on stress and temperature. Such a model is useful for high-temperature structure analysis and is practical because of the ease in determining material constants. The implicit integration is shown to result in two scalar-valued equations, and the consistent tangent modulus is derived in a general form by introducing a set of fourth-rank constitutive parameters into discretized kinematic hardening. The constitutive model is, then, implemented in a finite element program and applied to lead-free solder joint analysis. It is demonstrated that the implicit integration is very accurate if the kinematic hardening model of Ohno and Wang is employed, and that the consistent tangent modulus affords parabolic convergence to the Newton-Raphson iteration for solving nodal force equilibrium equations.

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We have investigated the behavior of moisture absorption by a nylon 6 stored in a chamber, which can separately control temperature and humidity in air, and examined the effect of moisture on the dynamic viscoelastic properties of nylon 6. The moisture absorption behavior was confirmed to obey the Fick's law of diffusion. The dynamic viscoelasticity of specimen generally shifted to that at lower temperature, as an effect of plasticization. The time-water content superposition was confirmed to hold in air at various relative humidities. The relationship between shift factor, log[α_H], and equilibrium water content has a form similar to WLF-type equation of time-temperature superposition.

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Circumferentially notched components of annealed copper were low-cycle fatigued under load-controlled condition being accompanied with mean load. In addition, their cyclic stress-strain responses were calculated under the corresponding loading conditions by means of elastic-plastic finite element method, where the constitutive equation proposed by the authors in their earlier paper was employed. The calculated nominal stress-diametral strain response at the minimum cross-section was in quite good agreement with the experiment, showing the validity of the present computation. The compressive mean stress generated at first one cycle at the notch-apex shakes down to be attenuated during the following cyclic loading under the condition of the load ratio R_p = -1.0, while this changes very slightly in the same direction during the further cyclic loadings at the R_p = -1/3 and 0. The stress ratio at the notch root R_σ is generally smaller than R_p, and the difference between them is much greater at R_p = -1/3 and 0 than at R_p = -1.0, in the sharper notch than in the duller notch, and under smaller applied cyclic loading than under the greater one. Incidentally, the tensile mean stress was yielded in the center region at the minimum cross-section of the notched components.

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A helical spring with rectangular wire cross section can conserve more energy than one with circular wire cross section in a limited amount of space. Therefore, it is used widely in press metal mold and other various machine tools. Recently, the rectangular wire helical spring with large pitch angle is used because of their large amount of deflection from the same free length. Rectangular wire helical springs have also been used as the helper spring in a suspension device for rally cars. Furthermore the rectangular wire helical spring with large pitch angle is attempted to be used as the suspension spring for the automobile. However, the accuracy of the results by Liesecke's theory on the stress and the spring constant of the rectangular wire helical springs has not been made clear, especially on the one with large pitch angle. In this research, the theoretical results are compared with the experimental ones and those by the Finite Element Method (FEM). New design formulae for rectangular wire helical springs considering pitch angle effects are derived for various aspect ratio of wire cross section by the FEM analysis.

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A new in-situ surface observation system under tensile stress with an atomic resolution has been developed for the purpose of the explanation of the deformation of the surface and the crack growth mechanism for thin films in the micro- and nano-mechanical systems. The mechanical properties such as Young's modulus can be determined at the same time. This observation system consists of the on-chip tensile testing system and a commercialized atomic force microscope (AFM). The on-chip testing system is characterized by a static loading mechanism with a flat spring and a test chip of single-crystal silicon of 15×15×0.5 mm. Particular attention has been paid to the suppression of the vibration which effects on images of the surface with an atomic resolution. Atomic images of the surface of mica can be observed under various tensile strains till the occurrence of the fracture. The growth of the cracks and Young's modulus for TiN thin film deposited on silicon (100) specimen can be also clarified.

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The reflection type laser photoelasticity that possesses high detection sensitivity on the birefringence measurement was developed to detect the stress of the film formed on the surface of a board. The magnitudes of principal stress difference and the directions of the principal stresses were obtained simultaneously and quantitatively using the developed equipment. However, in this type of photoelasticity, measurement error arises from the light reflected by the sample surface. In order to examine the effect of this surface reflection, the stress measurement of the stressed glass elates with the aluminum deposition on a side was carried out. The load of the 4 point bending moment was applied to the grass plates. The laser light penetrates the glass, is reflected on the aluminum, and returns. From this reflected light, the stress of the glass was measured. The reflected light intensity was adjusted by changing the thickness of the deposited aluminum. The result of the experiment showed that surface reflection has influence on the measurement. And, the calculation method which removed the effect of surface reflected light was examined.

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The purpose of this paper is to present a method of material design for the weight reduction, the high thermal radiation and the relaxation of in-plane thermal stress and centrifugal stress in a rotating disk without hole composed of functionally graded material (FGM) with arbitrary thermal and mechanical nonhomogeneities in the radial direction. The disk is subjected to an intermittent heating in an annular region near the outer radius and has an arbitrary variation of heat-transfer coefficient along the radial position on the upper and lower surfaces. The transient temperature field is analyzed by modifying Vodicka's method for one-dimensional boundary value problems in composite regions and the thermal stress and centrifugal stress are respectively obtained by solving approximately the equilibrium equations expressed in terms of the displacement component. The material design is carried out for the rotating disks composed of Ti+6 Al+4V and SUS 410 FGM, and Ti+6 Al+4V, PSZ and SUS 410 FGM.

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Cavitation erosion tests were carried out for Ti-Ni shape memory alloy solid and coating using stationary specimen method of vibratory apparatus. The alloy coating was made by sputter deposition and was heat-treated at 300, 500 and 700°C. The coatings without heat treatment and with treatment at 300°C were completely peeled off after reaching the substrate due to cavitation, and the coatings heated at 500 and 700°C were strong enough to have high resistance of the erosion. A transition of mass loss rate was observed against the temperature of heat treatment. The mass loss rate changes from high to low at 400°C, because of the crystallization at this temperature. The mass loss rate of the coatings heat treated at 500 and 700°C corresponds well with that of the alloy solid. It was concluded that the erosion resistance in Ti-Ni shape memory alloy coating is about 20 times superior to that of stelite 6B.

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The influence of surface roughness on fatigue limit is evaluated by a surface factor and a safe factor and they don't have the distinct physical meanings. To discuss a quantitative evaluation of surface roughness on fatigue limit reliability, the exact solution is given for a problem of an infinite plate with a complex profile under tension. The solution is obtained with the complex variable method. Some simple periodical notch problems are analyzed with the solution and also the method is shown to solve a problem of a complex profile.

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In this paper, a quantitative prediction method for the fatigue limit reliability is proposed by using statistical characteristics of hardness in a small region and mechanical condition in a small region based on a defect size distribution and a certain stress applied to a defect. And rotating bending and push-pull fatigue tests under R = -1 are carried out on quenched-tempered 0.5% carbon steels, whose average hardness is about H_v ≃ 600. Comparing a predicted fatigue limit reliability with experimental data, the applicability of the present proposed method is examined and confirmed.

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A quantitative prediction method for notch effect in fatigue limit reliability of high strength steels with defects or non-metallic inclusions is proposed with a stress concentration and scatter of Vickers hardness and defect size distribution. Especially in this report, the method can be used for a structure with a deep notch under zero mean stress. And fatigue tests of notched specimens are carried out on quenched-tempered 0.5% carbon steels: whose average Vickers hardness is about 600. Comparing a predicted fatigue limit distribution with experimental data, the applicability of the present method is examined and confirmed.

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It was previously shown experimentally that the effect of various factors influencing the fretting fatigue limit could be evaluated based on the local stress at the contact edge. In this report, the meaning of the local stress in fretting fatigue was studied. The crack analysis showed that the stress intensity factor change of a micro fretting fatigue crack was uniquely determined by the local stress irrespective of loading type and specimen size. Moreover, the fretting fatigue limit was the condition at which the micro crack remained as a non-propagating crack and this condition could be evaluated based on the concept of threshold condition of a short fatigue crack. It was concluded that the local stress can be a unifying parameter to evaluate the fretting fatigue limit.

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Rotating bending fatigue tests on shot-peening treatment (SP-treated) AC4CH aluminum alloy were carried out in order to investigate the effect of SP treatment on the high cycle fatigue properties. As the comparing fatigue property of the SP-treated material with fatigue properties of non-peened material, HIP-treated material and semi-liquid die casting (SL) material, the following conclusions were obtained. (1) Although the fatigue property of SP-treated material is most excellent in all materials, they are a few differences as compared with HIP-treated material and SL material. (2) The fatigue strength at 10⁷ cycles of AC4CH alloy is governed by the existence of cast defects near the surface. If the cast defects do not exist there, the fatigue strength at 10⁷ cycles of AC4CH alloy is as practically equal as HIP-treated materials and SL materials. (3) The fatigue life property of AC4CH alloys is significantly affected by fatigue crack initiation behavior. The reason why the SP-treated material has longer fatigue life than other material ones is that it has no cast defects near the surface by the effect of SP treatment. Moreover, the miniaturization of microstructure near the surface by SP treatment affect on fatigue life since generation of the slip in crystal grain, which cause the surface fatigue crack initiation, is prevented.

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Fatigue tests of SCM 440 chromium molybdenum steel were carried out under high mean stress. Prediction method of fatigue strength based on fracture mechanics was developed and the following conclusions reached. (1) It has been shown that the ΔK_th becomes constant value at strain ratio R_ε > 0.5, just as the fatigue limit becomes constant at R_ε> 0.5 .(2) It has been shown that the fatigue diagram could make without fatigue tests, if the range of stress intensity factor ΔK of intrinsic crack was compared with ΔK_th in various mean stress. (3) The prediction fatigue limit is in good agreement with the experimental value under high mean stress.

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Uniaxial tension fatigue tests were carried out in air and high vacuum environments using pieces made of high strength steel (SNCM 439) with various finishing conditions. Based on the results of fatigue tests and the data arranged by the initial stress intensity factor range (ΔK_ini), (i) effects of surface finishing and high vacuum environment on surface- and interior-originating fatigue properties, (ii) effects of high vacuum and inner environment of materials on the growth limit of the fatigue crack, were considered. The following results were obtained; (1) Interior-originating fractures were not affected by surface finishing conditions and surrounding environments. (2) The shape of the "Duplex S-N curve" depended on surface finishing conditions and surrounding environments. (3) Fatigue lives of surface-originating fractures in high vacuum and interior-originating fractures were much longer than surface-originating fractures in air. Surface cracks in high vacuum and interior cracks of materials grew from smaller defects whoseΔK_ini were lower than the growth limit of surface cracks in air. A lower growth limit of fatigue cracks and a longer fatigue life of interior-originating fractures were inferred from the effects of the inner environment of materials, which were similar to those of high vacuum environment.

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The tensile fatigue tests as well as tensile constant elongation-rate (CER) tests for GFRP/metal conical shaped joint, GFRP/metal adhesive joint, and GFRP/metal bolted joint are carried out under various loading rates and temperatures. The tensile fatigue strength as well as the CER strength for these three kinds of GFRP/metal joints depends clearly on time and temperature. The same time-temperature superposition principle for the deformation of matrix resin holds for the CER and fatigue strengths of the corresponding GFRP/metal joint. Therefore, the master curves of fatigue strength for those GFRP/metal joints can be obtained. It was clarified from these master curves that the dependence of time to failure, temperature and number of cycles to failure on fatigue failure load of each GFRP/metal joint shows very characteristic behavior, respectively, and that these dependences on the fatigue failure load of composite structures synthetically evaluated using temperature.

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The fatigue properties of a TiNi shape-memory alloy wire were investigated by both a rotating-bending test and a pulsating-bending test. The influence of strain amplitude, strain ratio, frequency and environment upon fatigue life was discussed. The results are summarized as follows. (1) The fatigue curves in the rotating bending and the pulsating bending intersect. In the region of low-cycle fatigue, the slope of the fatigue curve and the number of cycles to failure in rotating-bending are smaller than those in pulsating-bending. (2) The fatigue crack initiates at a certain part on the surface of a wire and grows with the number of cycles, resulting in final rupture. The larger the strain amplitude, the smaller the ratio of a fatigue fracture surface and the higher the average fatigue-crack growth rate. (3) In the pulsating-bending test, the smaller the strain ratio, the shorter the fatigue life. The smaller the strain ratio, the larger the ratio of a fatigue fracture surface and the higher the average fatigue-crack growth rate. (4) In the rotating-bending test, the fatigue life in water and in silicone oil is longer than that in the air.

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The objective of this study is to develop a method for evaluating corrosion fatigue crack propagation behavior at Christmas-tree-type low pressure (LP) steam turbine rotor groove. The rotor groove examined in this study has three hooks. Centrifugal force of the blade is supported through these hooks. Each corner of the hook can be a candidate for crack initiation site, therefore, the condition where cracks initiate and propagate simultaneously at several grooves must be considered. A procedure is presented to assess the crack propagation behavior under such a condition. It is shown that the crack propagation behavior is strongly affected by gap size between the rotor groove and the inserted blade root. The gap is introduced unavoidably within a manufacturing tolerance. Finally a simple method is proposed for evaluating residual life of the rotor groove after crack initiation is proposed.

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It is well known that the fracture toughness of a crack in a thin adhesive layer constrained by hard adherends depends on the thickness of the adhesive layer; however, the precise mechanism of the dependence has not yet been elucidated. In our previous study, we investigated the stress distribution around a crack tip in an adhesive layer using the finite element method (FEM), we discovered the presence of higher hydrostatic stress around a crack tip in thinner adhesive layers. In this study, the damage around crack tips in thin adhesive layers of rubber-modified epoxy resin is analyzed using the FEM in conjunction with Gurson's model, which can well describe the yielding of porous material such as rubber-modified epoxy resin. The decrease of the fracture energy with the decrease of the bond thickness can be estimated by this analysis, but it is not clear why the maximum fracture energy occurs at around 0.4 mm of bound thickness.

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Analytical expressions for the stress distribution along a through crack under mixed-mode (Mode l and II) deformation in a finite plate are developed, based on the complex-valued formulas on the stress and displacement of a two-dimensional crack in an infinite plate. Using these formulas analytically extended to the finite plate problem, the stress intensity factor K_I and K_II for Mode I and II can be determined from crack opening and sliding displacements along the crack, respectively. The expressions show that the geometry effects of the finite plate such as finite-width and length are directly reflected in the displacements along the crack. To demonstrate the present method validity, for an example case, Mode I crack opening displacements are calculated from FEM analysis of center cracked finite plates with fine mesh around the crack tip and used to evaluate the stress intensity factor K_I. The evaluated values K_I obtained from the present method are in good agreement with those obtained from conventional methods such as Isida's theoretical solution, Tada's empirical equation, a displacement extrapolation method and a method through the J-integral.

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Primitive deformation at the crack tip is an example of activation process. Performing a series of Monte Carlo and molecular dynamics hybrid simulations for the {110} <110>-crack in bcc crystal, it is observed that two primitive deformations, dislocation nucleation and expansion of hcp transition region, take place stochastically. Controlling the temperature and the strain of the system, the activation energy and the rate constant prefactor are determined. It is predicted that the effective brittle-ductile transition temperature becomes much lower than the activation energy (divided by Boltzmann constant) of dislocation nucleation when the observation time becomes of the order of millisecond.

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This paper demonstrates the crack detection of thick-walled non-magnetic metal plates by eddy current testing, which is difficult because of Kelvin skin effect generally. The purpose of this research is the development of an new eddy current testing probe for cracks in thick-walled plates and crack shapes quantitative evaluation. The probe was designed, based on the numerical computation using 3D fast eddy current code. The advantages of this new probe are strong eddy current on the back of specimens and gentle decrement of eddy current in the thickness direction. Through experiments, we confirmed that this probe can detect the back artificial defect with 0.5 mm thickness on IN-CONEL 718 specimen with 7.0 mm thickness. Reconstruction of crack shapes was performed based on the experimental results with the inverse problem code developed by authors. The length and depth of reconstructed defects approximately agree with those of real crack.

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In order to improve the accuracy and reliability of failure probability in PFM analyses, a PFM code PASCAL for evaluating the failure probability of an aged reactor pressure vessel has been developed. This code has a function to evaluate the effect of ductile crack extension, where the increase in fracture resistance by ductile crack extension is taken into account based on R6 method (Rev.3). Three fracture criteria were introduced including ductile crack extension analysis by R6 method analysis category 3. Using the NRC/EPRI PTS benchmark problem, the influences of fracture criterion were compared. Results of sample analysis showed the conditional fracture probability based on R6 method category 3 is much lower than that of K_1c/K_1a criterion. Especially, in low neutron fluence condition, the difference of fracture probability between R6 method Category 3 and K_1c-K_1c criterion even reaches 5 orders of magnitude.

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The dynamic response of two-dimensional particulate aggregation subjected to the oblique impact of a spherical projectile less than 15 m/s are investigated experimentally and also numerically by using discrete element method. The particulate aggregation is modeled by the 329 nylon spheres arranged regularly and two-dimensionally in a rectangular container. When the damping coefficient between particles is assumed to be in proportion to the contact force between particles, the numerical simulations agree well with the results measured by a high-speed video camera. The asymmetrical behavior of the particulate aggregation is explained by the distribution of velocity vector of individual particle and normal direction component of contact force between particles. The scattering behavior of particulate aggregation depends on the impact position of particulate aggregation and incident angle of projectile. It is found that the normal direction component of contact force between the base plate and the lowest layer of particulate aggregation shows dynamic M-shaped distribution under impact point.

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SH transient response for the graded inhomogeneous half-space with the elastic principal axis which tilted for the free surface, that is, the non-symmetric problem is considered. In the previous paper SH impact problem of the case one of the principal axis is coincident with the free surface (the symmetric problem) was analyzed by using the Cagniard method to obtain the closed form solution of stresses. These symmetric results are used as an analytical element to solve the non-symmetric problem. After the coordinate transformation is applied, SH transient response are numerically calculated to satisfy the virtual stress free boundary condition. Some results for C/C composite which SiC functionally graded coating is done are shown by the 3-D graphic representations.

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It is well accepted that articular cartilage adapts to changing mechanical environments. As the rubbing condition is getting severe, the articular cartilage will be worn, resulting in osteoarthritis, but little is known about the mechanism to osteoarthritis. It is important to clear the stress-strain state of cartilage and in chondrocytes under repeated cartilage deformation to know how osteoarthritis gets to start and progress. The purpose of this study is to investigate an influence of chondrocytes on stress-strain state of articular cartilage and an influence of position of chondrocyte on its depth-dependent deformation. FEM analyses predict time-dependent stress-strain state of articular cartilage because of fluid exudation, but material properties of chondrocytes do not affect the behavior of articular cartilage so much. The deformation of chondrocyte is depth-dependent and the largest time-dependent deformation behavior occurs in the surface layer. These results may clear how the transduction of mechanical stimuli concern about metabolism of articular cartilage via chondrocytes.

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In this paper, the fracture healing is simulated by using the cellular automata (CA) method. It is assumed that each cell has a property of bone, cartilage or fibrous connective tissue. Nine local rules are adopted to change the property of each cell against the mechanical stimulus, which is the strain energy density, and the existence of bone in the surroundings. As the simulation model, two dimensional sheep metatarsal model is considered and the fracture healing is simulated. The simulation results agree well with the ones by using fuzzy logic model and experimental data. It is shown that the CA method is one of the simulation method to express the fracture healing.

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