A distributed processing system has been developed, which is suitable for parameter surveys often carried out in the machine design with complicated processes such as structural analysis process, data conversion process and so on. The system consists of a Linux PC cluster and a graphical user interface on a Windows PC. An execution test showed that it was possible to maximize the efficiency of a job execution by reallocating computing load dynamically to each PC.

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The porous material is one of the promising functional materials, and its macroscopic properties are strongly dependent on the microscopic morphology. To study the correlation between the microscopic heterogeneity and the macroscopic properties, a novel digital imagebased analysis methodology is proposed in this paper, which consists of high resolution X-ray CT, digital image-based modeling, multi-scale stress analysis and geometrical morphology analysis. The proposed morphology analysis enables us to predict the microscopic stress concentration for spherical porous ceramics considering the heterogeneous dispersion of spherical pores and the macroscopic loading condition. The heterogeneity can be analyzed geometrically for very huge data with approximately 58 million voxel elements quickly. The morphology analysis is helpful for the multi-scale modeling and microscopic stress evaluation. The microscopic stress distribution is also discussed in association with the random heterogeneity for ceramics with open pores and with high porosity ratios.

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This study outlines a structural failure probability estimation method based on an improved directional simulation, where directional vector samples are generated adaptively with a situation of the failure domain of the structural systems. The conditional failure probability on a certain sample direction is formulated as a piecewise integration with respect to the radial variable. To improve the sampling efficiency, the dominant failure modes effective for structural failure probability are selected and the directional samples are generated from the sampling density uniformly distributed over the surface of the unit hypersphere centered at the mean value point of the failure domain, which is composed of the selected dominant failure modes. The dominant failure modes and the mean value point are estimated through a preliminary simulation. Numerical examples are presented to illustrate that the computational efficiency of the structural failure probability estimation based on the proposed method is improved.

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The evaluation of the wear conditions is an important subject in energy saving and resource conservation. Therefore, though the friction coefficient, etc. are measured, it is difficult to evaluate the wear conditions with Non-destructive inspection. In this study, the system which evaluated the wear conditions by the wavelet transform (WT) results of the detected AE signals during the wear testing was examined. As the result, the following things became clear. (1) From the WT results, the possibility of grasping the frequency ranges which rise from the wear phenomenon was able to be shown. (2) The possibility of deciding the sign of seizure was able to be shown. (3) The validity of this system could be explained by the collation with the experiment results.

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Ductile fracture of a polymer plate due to craze growth is characterized by a failure in the front of propagating neck. In this paper, the elastoviscoplastic constitutive equation, that explicitly represents the effect of craze, is rigorously derived. Through a thermodynamic discussion about arguments of craze rate function, a new craze evolution equation is proposed so as to express the craze concentration on the boundary between the oriented molecular region and the glassy one, and the craze annihilation in the oriented region, with a hydrostatic stress criterion of craze generation. Additionally, an evolution law of mean plastic strain affecting the craze growth is numerically identified for a polymer block with some circular holes. A finite element simulation is carried out in order to verify this model. The craze propagation and annihilation are visualized, and the possibility of failure prediction based on this model is also discussed.

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The present study reports the theoretical and experimental research of the state in a shock wave front in aluminum. Fundamental equations are derived from thermodynamic theory for the steady flow involving viscosity and heat conduction. The states in a shock wave front, such as temperature, equilibrium stress and viscous stress distributions, are calculated using the equations. The effects are investigated of viscosity and heat conduction in shock front formation. In order to consider the relation between viscous stress and strain rate in a shock front the theoretical results are compared with the experimental data obtained by VISAR (Velocity Interferometer System for Any Reflector). These results make the useful information for analysis of the structure of shock fronts to build the new hybrid wave code using the present theoretical solutions.

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In order to absorb side impact energy in an accident of automobiles, an impact beam is useful and its conventional type is made of steel. CFRP belts having lighter weight and higher tensile strength are recently developing for substituting steel impact beams. This paper presents the experimental and numerical results of CFRP thin belts under the impact loads and these results show a higher possibility of CFRP thin belt instead of a steel impact beam.

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For a material containing aligned penny-shaped cracks, the differential equation for the macroscopic total strain in the material is derived with respect to the crack density of the crack by using our differential scheme based on the incremental form of the Mori-Tanaka theorem. By solving this differential equation, the macroscopic total strain, the average interaction stress and hence the macroscopic elastic moduli are formulated as a function of the crack density of the crack. On the contrary to the results obtained by the ordinary Mori-Tanaka theorem, the resulting macroscopic elastic moduli asymptotically tend to zero as the crack density of the crack increases. The present results are good agreement with the results obtained by the self-consistent method. The volume fraction of the aligned penny-shaped cracks in physical meaning is obtained by comparing the resulting interaction stress with that derived from the Mori-Tanaka theorem.

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In order to examine the effects of frequency and the wave form of cyclic stress on the strain sensitivity of biaxial stress measurement method using an electrodeposited copper foil with microcircular holes, pulsating tension tests are done to the stainless steel specimen glued the copper foil and recrystallized copper foil. The higher the frequency becomes, the lower the strain sensitivity becomes.And in the case of sine wave, the relationship between stress amplitude σ_ph0.5 corresponding to slip occurrence rate of 50% at the periphery of micro circular holes and the mean strain rate 4nσ_ph0.5/Eper one forth cycle, where n is the frequency expressed by Hertz and K is Young's modulus of the material stress measured, is expressed as σ_ph0.5=.4109 (4nσ_ph0.5/E) +B. So, σ_ph0.5 to optional frequency can be estimated by this equation. Also, the strain sensitivity is affected by wave form and it becomes highest in the case of square wave and becomes lower in ramp wave than sine wave. If the copper foil is recrystallized, the strain sensitivity increases but the effect of the difference of wave form decreases.

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To investigate the effects of fusing conditions on the microstructures and on fatigue properties of thermally sprayed coating, three types of thermally sprayed specimen with different heating periods in the fusing process were prepared. Rotational bending fatigue tests and characterization of coating microstructures were carried out. By using a vacuum furnace for fusing, it is possible to get sprayed coating with very little porosity and high mechanical properties. Heating time in the fusing process strongly affects the fatigue properties the longer the heating time, the lower the fatigue strength. This is because longer heating process induces a segregation of the chromium compound in the coated microstructures. In order to achieve higher fatigue strength, shorter length fusing was performed by an induction heating system. However, the fatigue strength of the specimen is much lower than that of the vacuum furnace fused specimen. This is because a delamination between the coating layer and the substrate occurred during the fatigue process and the fatigue crack started at the newly created surfaces at the substrates.

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The effect of stress ratio in fatigue properties of bearing steel including long life region was experimentally examined under axial loading. As a result, the complicated S-Nproperty was, irrespective of stress ratio, well explained as duplex S-N characteristics obtained by superposition of S-N curves for surface induced fracture and interior inclusion induced fracture. Fish-eye marks were necessarily observed on the fracture surfaces failed in the latter fracture mode and an inclusion was found at the center of the fish-eye. It was finally found that the fatigue fracture of this steel in the long life region occurred through three different processes of (1) formation of the characteristic area of FGA, (2) crack propagation to form the fish-eye and (3) rapid crack propagation to cause the catastrophic fracture.

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Recently high-speed steel type white cast iron roll was developed and shows high wear-resistance and are widely used in hot strip rolling. However a crack caused with rolling accident in roll surface propagate rapidly and damage a roll performance. Then the investigation for crack propagation was carried out by numerical analysis with finite-element method and crack propagation test. The results concrete as follows ; (1) Crack propagates by contact with buck-up roll by means of shear mode (mode II). (2) Ordinary thermal crack less than 1 mm in length does not propagate, but abnormal mechanical crack more 1.3 mm in length caused by rolling accident propagate even under normal rolling condition. (3) Compressive residual stress of roll is not a accelerate factor for propagation of crack.

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In this study the plane electroelasticity problem for a functionally graded piezoelectric slab containing a crack perpendicular to the boundaries is considered. It is assumed that the electroelastic properties of the medium vary continuously in the thickness direction. The problem is solved under a fixed grip and a uniform electric field conditions applied to the slab away from the crack region. The stress intensity factors and the energy density factors are presented for embedded as well as edge crack for various values of dimensionless parameters representing the size and the location of the crack and the material nonhomogeneity.

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In this study the theoretical analysis of a thermoelectroelasticity problem is developed for a piezoelectric plate due to thermal loading under a uniform electric field and a fixed grip condition. The plate is a functionally graded material, meaning that its thermo-electro-mechanical properties are assumed to be continuous functions of the thickness coordinate. The plate contains an embedded or an edge crack perpendicular to its boundaries. The Fourier transform technique is used to formulate the problem in terms of a singular integral equation. The singular integral equation is solved by using the Gauss-Jacobi integration formula. Numerical calculations are carried out, and the mode I stress intensity factors and energy density factors are presented for embedded as well as edge crack for various values of dimensionless parameters representing the size and location of the crack, the material nonhomogeneity, the surface temperatures and the loading combinations.

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This paper focuses on the joint strength of Inconel 600 brazed with Pd-Ag-Mn and Pd-Ni-Co braze alloys. New palladium braze alloys based on the Pd-Ag-Mn system and Pd-Ni-Co system were developed for applications in high temperature environment : 30 Pd-60 Ag-10 Mn, 30 Pd-50 Ag-10 Mn-10 Co, 33 Pd-64 Ag-3 Mn (BPd-10), 40 Pd-50 Ni-10 Co, 30 Pd-50 Ni-10 Co-10 Cu, 40 Pd-49 Ni-10Co-1 B, and 40 Pd-47 Ni-10 Co-3 B. Mechanical tests included tensile test from 20°C to 800°C and tension-tension fatigue test at room temperature and 600°C for Inconel 600 brazed joints. The joints brazed with 40 Pd-50 Ni-10 Co had high tensile strengths from 20°Cto 800°C and good fatigue resistance.

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Study on the cellular responses to biaxial cyclic stretch requires a complex device giving two dimensional deformations to cell substrates. To carry out the biaxial testing easily, we have developed a mechanism that makes a conventional uniaxial device to biaxial one. By incorporating two three-bar linkages into a conventional uniaxial device NS-300, we obtained cyclic stretching motion perpendicular to its original stretch direction. Difference in the displacement between the two directions was less than 1.4% for a 10% stretching mode. By changing the linkage assembly, we can select two modes of biaxial stretching : simultaneous and alternate. The deformation of the silicone membrane on the bottom of a newly developed biaxial chamber was almost uniform in the central region of 12mm×12mm. We applied various modes of biaxial and uniaxial cyclic stretches to bovine aortic endothelial cells with this device, and found that the cells aligned in the direction with minimal substrate deformation, a well-known cellular response to cyclic stretch. This device is useful in studying cellular response to biaxial stretching for its easiness in extending capability of conventional uniaxial stretch devices to biaxial ones.

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