Copper powders were placed with mickel or cromium powder in a ball mill, followed by mechanical blending with aluminum borate whiskers at a slow rotary speed. Three type of copper alloy matrix composites were formed by hot isostatic pressing. The averagediameters of powders were about 30μm for copper powder, about 7μm for nickel powder andabout 10μm for chromium. The effects of whisker, nickel and chromium on mechanical and wear properties of copper alloy composites were studied. The wear properties were in vestigated by changing the applied load. There were uniform distribution of whiskers in the copper alloy composites. The ultimate tensile strength of the composites was not increased significantly by blending with the whiskers. The wear volumes of the composites dependedon the normal load where varied wear morphology from mild wear to severe wear. For Cu-Cr system composite, the wear volume was decreased by blending with whisker regardless of normal load. For Cu-Ni system composites, the wear volume increased with blending whisker under low normal load. However, at high load, the wear morphology of Cu-30Ni system composite microscopically differed from that of Cu-45Ni system composite. For Cu-30Ni system composite, the wisker resulted in the increases of wear volume. For Cu-45Ni system composite, wear volume decreased with blending whisker.

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Though genetic algorithms are effective for combinatorial optimization, they often need large number of function evaluations. Moreover, integration of analysis software with the genetic algorithm is sometimes cumbersome. Response surface methodology has been proposed recently for overcoming these two difficulties. In the present study, response surfaces are constructed in lamination parameters for laminated composites. The construction of the response surface in lamination parameters reduces the number of design parameters, with an attendant reduction of the design cost. Applicability of this approach is studied for optimizations of stacking sequences of simply supported laminated plate for maximization of buckling load. A two-stage approach, relying on initial continuous optimization, is used to zoom the response surface to the region of the optimum design for uncreased accuracy.

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In a former report, we proposed a probabilistic theory of propagation of ultrasonic waves in particulate metal matrix composite (MMC). That theory is based on the assumption that when ultrasonic rays impinge on a dispersed particle, they transmit by 100% through the particle. However, in practice, a percentage of impinging rays are considered to creep around the particle. In this report, using a theoretical model in which both transmitting and creeping rays exist, ultrasonic waves propagating in particulate MMC are analyzed. Fairly good agreement is seen between analyzed results and experimental results. Using this theory, the relationship equation between particle parameters (volume fraction, size) and ultrasonic parameters (arrival time, pulse width, amplitude) are derived.

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Rate dependence of mode II interlaminar fracture toughness of interlayer-toughened carbonfiber/epoxy laminates (T800H/3900-2, Toray) was investigated over a wide range of loading rate from quasi-static to impact (displacement rate, δ=0.01 mm/min-15m/sec). The fracture toughness was measured by using the ENF (End Notched Flexure) specimen with a universal testing machine at quasi-static loading rates and with a SHPB (Split Hopkinson Pressure Bar) system at impact loading rates. The load-displacement relation was non-linear below the maximum load point at all loading rates. Hence, the fracture toughness was calculated with considering the microscale crack growth preceding the macroscale unstable crack growth, which was enabled both by using a ramped incident stress wave and by estimating the equivalent load from the surface strain of the specimen at impact loading rates. The fracture toughness, wholly, showed positive rate dependence (i. e. the fracture toughness increased with loading rate). However, it, partly, showed negative rate dependence. The crack path was near the boundary region between the base lamina and the interlayer at quasi-static loading rates. This type of fracture was characteized mainly as the interface debonding between the carbon fiber and the epoxy resin, resulting a rough fracture surface. However, the crack path was inside the interlayer at impact loading rates. This type of fracture was characterized as the failure of the interlayer resin, resulting a smooth fracture surface. It was supposed that the transition of the frature characteristics might cause the rise of the fracture toughness at impact loading rates.

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This paper deals with initiation and evolution of cracking damage on 90° plies in cross-ply laminate. An energy approach is extended to predict the progressive ply cracking damage and the corresponding nonlinear stress-strain behavior of the cross-ply laminate under multi-axial in-plane loading. In this approach, the stress and strain condition for the progressive damage are determined by equating the decrease in potential energy to the released energy, where the former and latter are estimated from the stiffness reduction due to ply cracking damage and from the mixed-mode critical energy release rate for cracking of unidirectional ply, respectively. This approach provides us with the constitutive relation of cross-ply laminates including the progressive ply cracking damage. Tensile tests and numerical simulation based on the above approach were carried out on five kinds of CFRP cross-ply laminates which were different in stacking lay-up. The obtained results are as follows : (1) The stress-strain response of the laminates is affected by the ply cracking damage. (2) The stress for ply cracking initiation decreases with increasing laminate thickness even if the thickness ratio of 90° plies to 0° plies is constant. (3) The ply cracking damage behavior depends on the lay-up. (4) The above ply cracking damage theory fairly well describes the experimental results.

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Evaluation test of the laser cracking specimens applied to the ZrO₂/Ni functionally graded materials (FGM) and also applied to the non-FGM has been described. In this test, 30 mm disk specimens of these materials were exposed to the combustion gas of nitrogen tetroxide (NTO)/monomethyl hidrazine (MMH) propellant. The delamination and the vertical crack formation of the ZrO₂ thermal barrier coating were observed during the heating test. It has been found that the laser cracking method seemed to be effective at preventing delamination in the coating layer of the test specimens. The crack and the delamination formation mechanism for ZrO₂/Ni FGM test specimens were also discussed with a thermal stress analysis by using a finite element method.

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The distribution of contact pressure on the surfaces of a crack in a ceramic specimen is estimated by a 3D finite element inverse analysis. The strains generated by the introduction of a crack are measured with strain gages on a side of a specimen, and this datum is used as the input to the inverse analysis. To reduce the number of parameters to be determined, the microscopic deformation characteristics related to the surface roughness are modeled by a non-linear spring with two parameters. After identifying these two parameters, the contact pressure distribution is calculated by a direct analysis. In order to save the computational time, the effective method which makes the system of equations small is developed. This method is applicable to a wide range of inverse problems.

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The effects of the local damage field on the asymptotic crack-tip stress field of a Mode I crack in a nonlinear-hardening material are discussed. Three kinds of the damage distribution 1-(D/D_cr)=h (θ) r^m represented by a power function of radius r from the crack-tip are postulated for the damage variable D, and the damage effects are included into the power hardening relation by means of the effective stress concept of continuum damage mechanics. For a given strain hardening exponent n of the power hardening equation, the exponent p of the resulting asymptotic stress fields σ_u∝γ^p is found to be governed by the exponent m of the power-law damage distribution. When m increases, p is found to increase from a singular (negative) HRR exponent p=-1/(n+1) to a nonsingular (positive) value, which coincides with the previous analytical result for a Mode III crack in a linear elastic-damage material. A sufficient condition M>1/n for the nonsingular crack-tip stress is obtained for both plane stress and plane strain states. The effects of the strain hardening exponent n and the stress states on the p-m-n relation are discussed in some details. The damage effects on θ-distribution of the asymptotic stress fields are also discussed.

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A weight function which can be applied in evaluating the stress intensity factor of a circumferential crack in a finite length cylinder under arbitrarily distributed stress on crack surfaces was derived based on the closed form stress intensity factor equation previously developed by the authors. The effects that structural parameters, such as cylinder length, and stress distribution have on the stress intensity factor can be easily evaluated systematically by applying this weight function. The validity of the weight function was confirmed by numerical examples for linear, uniform and quadratic stress distribution. From these examples, the effect that cylinder length has on the stress intensity factors for these stress distributions was quite large, and the weight function derived in this paper will give a practical solution to these problems.

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This paper examines the effects of interaction and coalescence of multiple surface cracks in water environment on fatigue behavior in brittle materials such as glass ceramics. For glass ceramic specimens with the three collinear cracks which introduced the different crack center distances by Vickers indentation, the cyclic fatigue tests in water environment were carried out with four point bending load. It was found that the time to failure for glass ceramics in water environment significantly decreased with the decrease in the crack center distance of multiple surface cracks, and was shorter than that in air. Moreover, from the crack growth parameter for a single crack, the predictions of the time to failure for multiple surface cracks were conducted by taking the interaction and coalescence into consideration. The predictions using the proposed crack growth model agree well with the experimental results.

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In order to clarify the fatigue behavior and fracture micromechanism for cold rolled steel foil of semi-austenitic precipitation hardening stainless steel SUS631 so as to evaluate its fatigue characteristics, fatigue tests and hardness measurements before and after the fatigue tests were carried out on the stainless steel foil of 0.05mm in thickness for as-received material and two kinds of ageing treated materials. The fracture surface of these foil specimens was observed by Scanning Electron Microscopy (SEM). The main results obtained are summarized as follows. (1) The fatigue strength of as-received material was improved by ageing hardening treatment, the fatigue limit of the material ageing treated at 753 K for 1 hour was larger than that at 703 K for 1 hour. (2) After fatigue testing, the hardness of as-received material was increased, but the hardness of ageing hardening treated materials was decreased. The variations in the hardness before and after fatigue tests for these materials indicated that as-received material showed cyclic hardening behavior, and ageing hardening treated materials showed cyclic softening behavior. (3) From these observed results of the fracture surface and the cross section of fatigue cracks, there were distinctions in the crack growth path, failure pattern and fracture micromechanism on these materials, furthermore, the fatigue behavior of the foil material was very different from that of a bulk material.

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Low-cycle fatigue tests were performed at-140°C using commercial grade pure iron having average ferrite grain size of 400μm. A crystallographic examination of deformation twins around the fracture origination site has been carried out based on detailed observation of fracture surface using scanning electron microscope. The following two conclusions have been obtained. (1) For all the observed internal fracture modes in which internal cracks initiate at (i) the intersection of a deformation twin and a grain boundary (T-B type), (ii) the intersection of deformation twins (T-T type) and (iii) the intersection of a deformation twin and an inclusion (T-I type), the deformation twins which result in the final fracture of specimens belong to the {112} twinning group defined in this paper. (2) In the case of T-T type, an intersection of definite kinds of deformation twins among the {112} twinning group intersecting along <021> direction causes a cleavage fracture on {001} plane.

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The low-alloy cast steels, which have the same chemical composition show three types of microstructures, i. e. bainitic structure (material SNA), pearlitic structure (material SNB) and mixed structure (material SNC) by changing heat treatment conditions. The authors have been investigated by the rotating bending fatigue tests and have been observed on the specimen's surface for fatigue crack initiation by the successive-taken replica method and fracture surface with SEM. The main experimental results are shown as follows ; (1) The fatigue limits of SNA, SNB, SNC and SNC_s were 430, 225, 270 and 300 MPa, respectively. (2) The fatigue cracks of all specimens initiate at the blow holes, SNB, SNC, SNC_s and SNA showed aspect of ductile fracture and brittle fracture on fracture surface. (3) The fatigue limit of experimental data becomes higher than that of the estimated values by Murakami et al's eq.

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The propagation behavior of fatigue cracks was investigated under various stress ratios using structural carbon steel (JIS-S45C) specimens with small surface pre-cracks. The threshold condition of crack extension from pre-cracks was given by a constant value of the effective stress intensity range which was equal to the threshold value for long cracks irrespective of the stress ratio. Cracks initiated from precracks were arrested under lower stress amplitudes because of the development of crack closure with crack growth. The cyclic resistance-curve-method was used to predict the fatigue thresholds of the precracked components. The predicted values of the fatigue limit for crack extension, the fatigue limit for fracture, and the length of non-propagating cracks agreed very well with the experimental results. The effect of the mean stress on the fatigue limit of smooth specimen was successfully predicted by the cyclic resistance-curve-method.

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A simplified version of the cyclic resistance-curve-method for predicting the fatigue thresholds of pre-cracked components under mean stresses was proposed. The method requires one material data such as the hardness or the tensile strength for prediction. The relation between the Stage I nonpropagating crack length and the stress amplitude was unique irrespective of the stress ratio. The length of the Stage I cracks was given as a function of the applied stress and the Vicker's hardness. The fatigue limit of smooth specimens and pre-cracked specimens could be predicted from the hardness under arbitrary mean stresses by using the simplified cyclic resistance-curve-method. The fatigue limit predicted by the simplified method was larger than that by the original resistance-curvemethod. The predicted values of the fatigue limit for crack extension, the fatigue limit for fracture, and the length of non-propagating cracks agreed very wall with the experimental results.

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The sintered cemented tungsten carbite alloys having with binder phase, Co, are used that the materials for the tip of cutting tools and dieses. Then, surface of these tool parts are coated with ceramic thin film, i. e. titanium carbite, TiC, film and titanium nitride, TiN, film by physical vapor deposition, PVD, method or chemical vapor deposition, CVD, method. In recently, many researchers are estimated of physical properties and growth behavior that the diamond thin film was coated on the surface of various tools by thermal-filament CVD method. However, quite a few problems remain unsolved regarding the mechanical properties, it is important to know these properties of a diamond thin film on WC-Co alloys. This paper was mainly studied about the effect of diamond coating on fatigue strength of the sintered tungsten carbite alloys including with binder phase, Co, at 10, 16 and 25 wt.%. Then, the growth behavior and occurrence of thermal residual stresses of diamond film were evaluated by using for the Raman spectra analysis and X-ray diffraction method. As results, the fatigue strength of this material was depended on growth behavior and residual stress of diamond film.

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This study was done to clarify the influence of complex deterioration on fatigue reliability. Carbon fiber reinforced and glass fiber reimforced PEEK (poly-ether-ether-keton) that is thermal plastic was examined to construct the life cycle design intended to decrease environmental stresses. Specially, the influence of recycling process and high environmental temperature on the fatigue reliability of fiber-reinforced PEEK were experimentally examined. Main results were as follows ; (1) It was noted that the S-N curves of recycled PEEK/CF and PEEK/gf materials were as nearly equal to that of virgin material. (2) The macro crack has been initiated on specimen at fatigue limit (N=10⁷ cycle) of recycled gf material, and its crack was not propagated. On the other side, it has been not initiated on CF materials whether Virgin or recycled material. (3) The influence of the declining of fiber length by recycling process on fatigue strength of PEEK materials was small. (4) The influence of recycling process on PEEK/CF and PEEK/gf material could not be found by the fractograhy using SEM and the measuring of temperature rise on surface of specimen. So it was understood that the fracture mechanism of recycled material is squal to that of virgin material. (5) The results of fatigue crack propagation test to make clear the non-propagation crack showed that the fatigue propagation property of recycled material is equal to that of virgin material.

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When an isotropic solid sphere is suddenly subjected to an instantaneous heat source, a stress wave occurs at the moment thermal impact is applied. The stress wave proceeds radially inward to the center of a sphere. The wave may accumulate at the center and give rise to very large stress magnitudes, even though the initial thermal stress is relatively small. This phenomenon is called the stress-focusing effect. In this study, we certify to the stress-focusing effect in a glass solid sphere by using a Nd : YAG pulse laser. We compare the experimental results with the theoretical values and show the mechanism of stress-focusing effect in a solid sphere.

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In this paper, the singular stress field around a bonded edge point in a bimetallic beam subjected to pure-moment bending, three- or four-point bending is analyzed by the body force method. A particular attention is paid to exactly simulating the singularity at the edge point by numerical calculation. Based on the numerical results, the effect of the beam geometry and the material combination on the stress intensity factors are investigated.

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An evaluation method of bridging stresses was developed on the basis of the bending of a deepnotched specimen by an inverse analysis. The inverse analysis program to determine bridging stresses from bending data is opened at the internet address (http : //www. ME. kurume-nct. ac. jp/∼kmori/). Using the method, we evaluated the grain-bridging stresses of polycrystalline alumina ceramics with the mean grain size of 3μm and 11μm. The results obtained were as follows : (1) the mean grain size had little effect on the maximum bridging stress for alumina ceramics and, (2) there was no correlation between the maximum bridging stress and the mean bending strength for alumina ceramics.

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It causes sometimes rotary machineries to vibrate when there are unbalanced forces into them. In that case, we usually make them balanced forces. So we have investigated as to the stress intensity factor K₁ on the rotating disk having cracks under the unbalanced force by means of both the photoelastic freezing method and the caustics method. In conclusion, it seems that the values of the stress intensity factor K₁ at both the point of nearer and the opposite site to the unbalanced force are higher than those of not near it. Therefore, if there are the unbalanced forces on the rotating body, that is more possible to destroy it.

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Linear stress analysis without body force can be easily solved by means of the boundary-element method. Some cases of linear stress analysis with body force can also be solved without a domain integral. However, domain integrals are generally necessary to solve the linear stress problem with complicated body forces. This paper shows that the linear stress problem with complicated body forces can be solved approximately without a domain integral by improved multiple-reciprocity boundary element method. In this method, the distribution of complicated body forces is interpolated by integral equation. A new computer program is develoed and applied to several problems.

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A method of the elastic analysis was studied for the double wall corrugated fiberboard (DWCF) made of kraftliners (KLs) and semichemical corrugating mediums (CMs) under the uniform bending in the moment axis perpendicular to the machine direction (MD). Then relationships between stresses, shapes and elastic moduli of KLs and CMs were discussed by this analysis method. The stress decrease of KL is induced by the increase of its KL strength, and the stress of CM increase with the increase of its CM strength. The stress of CM in the increase side of CM wavelength increases with the increase of the wavelength for CM, and stresses of KL and CM increase with the decrease of the CM wave-height. The maxium stress of KLs is on the outer surface in the low strength side, and the maximum stress of CMs is on the inner surface at the KL·CM joint in the low strength side.

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The influence of strain rate ε on the pseudoelastic properties associated with the martensitic transformation was investigated by tensile tests for TiNi shape-memory alloy wires. The results were summarized as follows. For ε&lnE;10%/min, the martensitic transformation stress and the dissipated work increased but the reverse transformation stress and the strain energy decreased with an increase in ε. For ε&gne;2%/min, these characteristic values associated with the martensitic transformation did not depend on ε. The dependence of these pseudoelastic properties on ε was observed also after the mechanical training. In the case of designing SMA elements using the pseudoelastic properties associated with the martensitic transformation in applications of SMA, it is important to take account of the dependence of pseudoelastic properties on ε.

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Experimental evidence and theoretical analysis are presented for the bending of a soft ferromagnetic beam plate in a magnetic field. The experiments were conducted in the bore of a superconducting magnet at room temperature. Ferritic stainless steel SUS 430 is here used as the cantilever specimen for bending test. The experiments show the predicted increase in the deflection and strain with increasing magnetic field. The theoretical analysis is based on a classical plate bending theory for magneto-elastic interactions in a soft ferromagnetic material. Numerical calculations are carried out, and the deflection and strain are obtained for several values of magnetic field and geometrical parameter. A comparison of the deflection and strain is made between theory and experiment and the agreement is good for the magnetic field considered.

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This paper describes the numerical analysis of normal impact of an elastic cylinder onto a rigid wall. The phenomenon of impact and rebounding is discussed from the angles of (a) three dimensional effects of stress waves and (b) frictional force acting between the struck end of the cylinder and the rigid wall. The computational scheme is based on a lumped mass spring model whose equations of motion and strain-displacement relations are identical in a finite difference context. These difference equations were numerically integrated by applying the Runge-Kutta-Gill method. The dimensional effect of the cylinder on the coefficient of restitution was evaluated.

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This paper presents analytical solutions for 3-dimensional anisotropic problems containing steady-state line source of heat and elliptic cavity or elliptic rigid inclusion considering an arbitrary direction of the principal axis of elasticity. heat conductivity and thermal expansion. Mechanical boundary conditions treated here are free and fixed boundary, and thermal boundary conditions are isothermal and adiabatic boundary. In the last part of this paper, we show several numerical examples and the effects of anisotropy and its inclination are shown by many graphical representations.

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The longitudinal impact tests of an aluminum circular tube were carried out using a gas gun. In the gas-gun apparatus, the tube which was accelerated using nitrogen gas at constant pressure, collided with a hardened load cell. The inner and outer diameters, and thickness of a tube were measured after impact and the deformation modes of the impact end were evaluated. Additionally, impact-welding of an aluminum tube to a steel target was attempted using the gas-gun having a vacuum chamber. The following results were obtained. The increase of a wall thickness caused a deformation mode to transit from a dynamic bulging to a progressive one. The stagnation area of the metal flow at the impact face of a tube was observed and the flow was not dependent on the thickness. Additionally, it was confirmed in a tentative experiment that a circular tube is impact-welded to a steel target in the stagnation area.

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Nowadays our society demands the manufactured goods which are effective to reclaim, because natural resources are tendency to deccrease. So we should not noly reinvestigate the materials of goods, but also originate a new design method and a product system. Then we have investigated the srtucturing method and the strength about the beams whose material are scrapped paper. When the beam by scrapped paper is loaded, the deformation is large and moreover the cross section dose not mentaine flat. Therefore we cannot apply the traditional 'theory of elasticity' to the analysis and estimation of the deformation and strength. In this paper, we propose a new estimation method by analyzing the swelling caused when the papercraft beam is bended.

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The present paper describes the eigenvalue problem of beam with uncertainty on cross-sectional area. The cross-sectional area of the beam is expressed by the form containing stochastic variables, and the stochastic finite element method is applied to evaluate the influence of the uncertainty to the eigenvalue and the eigenvector. Numerical analysis is carried out with respect to the uniform beam and the optimal beam with the maximum first eigenfrequency. The influence of the uncerfainty of the beam cross-sectional area to the eigenvalue and the eigenvector is shown.

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A practical approach to the accuracy improvement of three-dimensional BEM (boundary element method) analysis is presented. With a specified degree of an element, an adjustment of interpolation function is carried out for every element on a curved surface boundary. The main idea of the adjustment is to change the relative positions of interpolation nodes to fit the boundary better. By obtaining a high accuracy of shape approximation, the quality of BEM analysis can be improved. This method is tested by the experiments using a few typical curved surfaces. The results of the experiments presented here show that the reduction of shape error can lead to an obvious accuracy improvement of BEM analysis, especially when the discretization mesh is coarse. This method is useful to improve the quality of the p-adaptive method.

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A new formulation for the boundary element analysis of inhomogeneous/nonlinear POISSON problem was proposed previously by present authors. The formulation is further extended here to cope with the case where derivatives of unknown function are included in the inhomogeneous terms. Two polynomial interpolations in terms of the space coordinates are employed : one for the inhomogeneous term and the other for the unknown function. Taking the computing points on the boundary as well as inside domain, the equations on these points are employed to determine the unknown coefficients in the polynomials by using the least square method. Two-dimensional examples are considered.

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The damages of ropes due to impact stress become an important problem as the interference of ropes becomes stronger. The interference of multi-layered ropes around hoisting drums occurs at the places where string rope encounters the helical rope and the crossover of the second layer. In this paper the interference of multi-layered ropes is analyzed by means of geometrical method. Using the expression of the crossover that was given in the previous papers by the present authors, the critical fleet-angles of the interference is analyzed and numerical calculations are conducted for the 3 variables nonlinear equations. The data for the optimal design of geometrical shape of a hoisting mechanism are obtained.

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This paper describes the effect of the constitutive relationship on the Rockwell A scale hardness using an elastic-plastic finite element method and studies the effect of thickness and width on the hardness. Yield stress and work hardening coefficient and exponent had a significant effect on the hardness but Young's modules and the coefficient of friction were not influential to the hardness. A prediction method of Rockwell A scale hardness was proposed. The method estimated Rockwell hardness within a ±10% error for HRA=30∼75. Limitation of thickness and edge of the sample on the hardness were also discussed in relation to JIS and ISO standards.

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In this study, we evaluated the compressive properties of soft rubber using the modified split Hopkinson pressure bar method. The soft rubber is used to cover the ink roll surface of a press, and is subjected to impulsive loading each time the roll rotates and contacts another roll. In carrying out the experiment, first, strain waves in pressure bars made of PMMA were investigated and actual strain applied to a specimen was estimated using the transfer function which calculated the dispersion characteristics of strain waves in the pressure bars. Second, the soft rubber was tested using PMMA pressure bars, the obtained strain was processed by the transfer function, the dynamic stress-strain curves of the soft rubber were obtained, and strain rate dependency on the stress-strain curves was investigated. Third, the determination of the constitutive equation of the soft rubber using the Voigt model was carried out, and stiffness and damping parameters were identified.

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In order to solve the effect of the surface pretreatment of a substrate on nucleation, three dimensional numerical simulation of the nucleation of diamond on silicon substrate by the CVD method was conducted. Diamond thin film has been guessed to be connected to the substrate by the nuclei grown at the beginning of deposition. In fabricating of diamond thin film, it is important to understand the number of nuclei, namely, nucleation density. The fact that nucleation density on a pretreated substrate is much higher than that on substrate without pretreatment is known empirically. In this paper, a three dimensional nucleation model that consists of a pretreated silicon substrate and reaction gas was proposed. Scarring on the surface of the substrate introduced by surface pretreatment was modeled by a V-shaped notch having two point defects. The model was verified by performing three dimensional numerical simulation of nucleation.

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The nondestructive inspection of the welded region is very important for quality control. The purpose of this study is to develop a methodology for nondestructive evaluation of the function of the spot-welded joint. In the previous paper, the system that consist of an ultrasonic inspection device and neural network was proposed to evaluate the tension shearing load. The welded region's geometry in resistance spot welding of a two-plate joint was inspected by parallel scanning over the region by ultrasonic inspection. The neural network learned the pattern sets dealing with the interaction between the scanning graphs and the tension shearing load of spot-welded joints. The validity of the previous system was confirmed by comparing the output of the network with the experimental results. However, it had been serious problems for improving the accuracy of the tension shearing load that the learning efficiency of the neural network was not good and the internal structure of the network was involved (the number of the input layer's units was 2401 units). In this paper, fractal dimension is introduced to characterize the scanning graphs, and the application of the dimension is proposed as the input data of the neural network. The following became clear after the investigation : (1) The scanning graphs showed fractal characteristics. (2) The number of the input layer's units was reduced from 2401 to 98. (3) The accuracy of the evaluation and the learning efficiency of this network were much better than the previous network.

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The seismic response characteristics of thin cylindrical shells under vertical and horizontal seismic excitation, concerning shear-bending buckling, was analytically investigated using two-degree-of-freedom system with non-linear restoring force characteristics. The plastic deformation in horizontal direction advances when the axial compression caused by vertical seismic excitation reduces the horizontal load carrying capacity. Thus the horizontal response amplification occurs due to the vertical seismic excitation. In this report, the response amplification is analytically investigated with different input waves and different cylinder models and the response amplification factor predicted by the linear response spectra of the input waves is proposed.

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In order to determine the controlling mechanism during the superplastic deformation process of a commercial 5083 Al-Mg alloy, superplastic properties have been investigated using constant strainrate tensile tests at the temperatures between 773 and 843 K and over a strain rate range from 10^-5 to 10^-1s^-1. The analysis from the experimental results reveals that the true stress exponent is two, and the true activation energy for superplastic flow is similar to lattice self-diffusion of aluminum (142 kJ/mol). All mechanical data can be represented by a single constitutive equation for superplasticity, which indicates that the dominant superplastic deformation mechanism is grain boundary sliding and the rate-controlling step in accommodation process is considered to be controlled by diffusional-flow-related phenomena within the grains during the superplastic flow. Also the microstructual dynamics with grain growth and cavitation during superplastic straining can reveal that the grain growth causes increase in flow stress and decreases in strain-rate sensitivity of flow stress, and the extensive cavitation leads a limited value in elongation-to-failure.

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Cylindrical deep-drawing tests were carried out for roll-bonded stainless-steel/aluminum laminates. The limiting drawing ratio (LDR) was found to be higher when a punch contact metal was strong material (stainless-steel) compared to the opposite case of reversed blank-set condition. In order to find the reason for the phenomenon, the effect of the blank-set condition on the maximum punch load for a given diameter of a blank and the fracture load at LDR was investigated. It was found analytically and experimentally that the fracture load of the laminate subjected to stretch bending at a punch corner was higher when a punch contact metal was strong material compared to the opposite case. From this result, it is clear that the difference in LDR between both the cases is mainly due to the difference in the fracture load of the laminate at a punch corner.

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Free Mesh Method, which is a kind of meshless method, is simple, accurate and suitable for parallel computing. In this method, the total stiffness matrix is obtained by adding the temporary element matrices, so this method does not require connectivity between nodes and elements as an input infomation. This paper describes anapplication of Free Mesh Method in 2 dimension at the stage of creating a set of temporary triangular elements around each nodes. For implementation, this system is desgined by an Object-Oriented approach in order to provide a efficient program for every algorithm and data structure, from geometical point of view.

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The evaluation of sound velocity, elastic constant of thin film has not been well established. The relation between electrical resistivity and sound velocity has been clarified from the calculation on the temperature dependence of electrical resistivity by well-known linear response theory. From the experimental data of electrical resistivity, we evaluated sound velocity and elastic constant of thin films by using the linear response theory, pseudopotential method. We also confirmed the method to evaluate the mechanical properties of thin film by measuring electrical resistivity.

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The theory of plasticity in soil has been established in such a framework that the hardening modulus h vanishes when volumetric compressive strain rate ε_p is zero. In general, soil shows dilatancy under relatively low pressure and h becomes negative. This is called strain softening. We have discussed the criterion of plastic instability in soil. In plastic instability the state which permits multiplicity of the solution arises. Consequently, the criterion is shown to be characterized by h=0. However, at ε_p=0 the plastic instability is not generally observed in practice. Furthermore, for h<0, stable deformation has been observed in many cases. Such inconsistencies exist between the theory and the observation. Next, we point out another inconsistency in the loading criterion of strain softening. The loading criterion does not clearly distinguish strain softening from unloading. For resolving these inconsistencies, it is necessary to make the expansion characteristics of the yield surface consistent with the hardening properties of soil. Then, we can exclude the phenomenon of strain softening. Such conformity of hardening characteristics in yield surface with hardening properties of soil makes it possible to develop a unified theory of plasticity in soil.

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Observing the human upper limb from the point of view of mechanics, every degree of freedom of motion is actuated and controlled by more than two muscles. Many biomechanical researchers have investigated the principles of the complex workings of human muscles using a mechanomathematical model, to obtain more knowledge about the musculoskeletal system control. In this paper we describe a method of numerical analysis of muscle force in a human upper limb during flexion of the shoulder joint. Because no muscle force can be calculated from only the equilibrium equations of force or moment, the optimization method using Lagrange multipliers was applied to this analysis. Muscles were modeled by a straight line from the origin to the insertion. Parameters in the object function were selected to express the muscle properties acting only in the direction of the contraction. Therefore, the synergist and the antagonist could be separated analytically. Moreover, the distribution of muscle force in the wide area of the muscle-bone adhesion depends on shoulder joint angle. Therefore, the muscle-bone adhesive point was also determined to minimize the objective function. The results obtained from this analysis were confirmed by experiments using electromyography.

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The muscle contraction occurs due to the relative sliding motion between the thick myosin and thin actin filaments. Actomyosin is a molecular machine that transfers chemical energy produced by ATP hydrolysis to kinetic energy. The investigation of muscle contractile mechanism at the atomic/molecular level has been motivated, because X-ray structures of actin and myosin SI monomer have been determined. Therefore, in order to study the structural heterogeneity and atomic fluctuation which can be related to the kinetic function, the molecular structure analysis of actomyosin has been carried out by using the molecular mechanics simulation code"AMBER". 3-D molecular structures of actomyosin adopt three models which consist of three kinds of myosin Sl (without ATP, with ATP, and with ADP) and F-actin to reveal the fundamental micro-mechanism of motility assay. The minimum-energy conformations of actomyosin in three cases are determined by molecular mechanics analysis. The differences of atomic coordinates and potential energy distributions show the existence of the local packing and heterogeneous material characteristics. Next, the fluctuations of those conformations are studied by the molecular dynamics analyses. The fluctuations reveal the dynamic properties at the atomic level and the possibility of meso-scale structural changes and emerging the whole molecular motion.

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