Finite element method and boundary element method were applied to develop the low-stress and low-noise lightweight wheel. First, stress analyses for the existing wheels under the condition of drag braking and track loading were performed. Following these analyses, an optimization methodology was developed and applied, leading to the development of new plate shapes of wheel whose stresses generated were lower than that of conventional wheels. Candidate plate shapes were selected based on the analyses. Next, eigenvalue analysis and transient dynamic analysis were carried out for the wheels. At the same time, to verify the analytical results, these wheels were manufactured and experiments were implemented. Finally, sound analyses were performed and results were compared with that obtained by field measurements. From this study, a new plate shape of lightweight railway wheel was obtained that reduces the radiated noise as well as the maximum stresses generated in the plate region.

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Temperature and thermal stress in cylindrical vessels were analysed for the thermal stratification of contained fluid. Two kinds of temperature analysis results were obtained such as the exact temperature solution of eigen-function series and the simple approximate one by the temperature profile method. Furthermore, shell solutions of thermal stress were obtained for the simple approximate temperatures. Through comparison with FEM analyses, these solutions were proved to be adequate. The simple temperature solution is described by one parameter that is the temperature decay factor. The shell solutions of thermal stress are described by two parameters. One is the ratio between the temperature decay factor and the load decay factor. Another is the non-dimensional width of stratification. These solution are so described by few parameters that those are suitable for the simplified thermal stress evaluation charts. These charts enable quick and accurate thermal stress evaluations of cylindrical vessel of this problem compared with conventional methods.

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A gold (Au) micro-interconnection, which connects through-hole electrodes in a three-dimensional chip stacking LSI, is composed of several tens of grains. The anisotropic property of grains influences on the mechanical reliability if the size of the interconnection becomes small in comparison with the grain. In this study, the stress distribution in the Au micro-interconnection is invistigated by using the finite element method (FEM) analysis. The crystallographic structure of the Au micro-interconnection is obtained by a three-dimensional simulation based on a nucleation and growth model. The FEM analysis shows that the stress is concentrated on the region near the micro-interconnection/substrate interface edge and that a stress singularity exists there. The stress distribution of the micro-interconnection varies owing to the microscopic structural factor, which is due to the shape and crystallographic orientation of grains. It is found by statistical evaluations of plural analytical models that the stress variation nearly follows a normal distribution.

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The relation of secondary injection-molding condition to the interfacial structure and shear welding strength of polyoxymethylene was investigated and following main results have been obtained. (1) The welding strength intensifies with increases of the secondary injection-molding speed and temperature. (2) With the increase in welding strength, the elongation to shear fracture becomes large also. The fracture mechanism of welding specimen changes from the interface debonding to the fracture with plastic deformation. (3) The higher the injection-molding speed and temperature, the molecule activation energy at the welding interface becomes high. So, the surface layer crystallization of the first molding is promoted and the trans-crystal layer is easy to be formed in the secondary molding side. It is thought to be advantageous to the improvement of welding strength. (4) Since the fracture starting point of welding specimen is at the welding interface or the surface layer of the first molding, the maximum welding strength is mainly determined by the strength of the surface layer.

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The copper electroplating is tried to apply on the fabrication of Large-Scale Integration (LSI) besides other methods because of its excellent via/trench filling ability, good adhesion and lower process temperature and cost. Then, in the electroplating process, estimating the growth rate of the electroplating in real-time is essential. It is able to estimate the growth rate from the current density on the LSI wafer surface because the growth rate of the electroplating is proportional to the current density. However, measuring the current density on the LSI wafer surface directly is impossible. In this paper, a new monitoring method to estimate the growth rate of the electroplating by using magnetic sensors is developed. We focused on the magnetic flux density induced by the current density in the electroplating device. The present method is measuring the magnetic flux density outside the electroplating device by using magnetic sensors, and estimating the current density on the LSI wafer surface by applying the inverse analysis method. In order to demonstrate the effectivity of the present method, two cases of numerical simulations, which take account the measurement error, are performed. The results show that this method could be applicable to practical problems.

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An instantaneous phase-stepping technique using a CCD camera equipped with a pixelated micro-retarder array is applied to the study of quasi-static crack growth in a quenched thin glass plate. The distributions of the principal direction as well as the principal stress diference around a growing crack tip are obtained by instantaneous phase-stepping photoelasticity. Then, not only the mixed-mode stress intensity factors but also the T-stress are evaluated from the distribution of the principal stress difference, and they are validated using the reconstructed phase maps. By applying the proposed method to the sucsessive images, the time-variations of the fracture mechanics parameters are evaluated quantitatively. Results show that the proposed instantaneous phase-stepping technique is effective for the study of the crack growth behavior in a thin glass plate

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In order to describe cyclic plasticity phenomena the plastic stretching within a yield surface has to be considered. Subloading surface model categorized in the unconventional plasticity models and describing a smooth elastic-plastic transition would be applicable to non-proportional loading process including cyclic loading behavior of materials with a smooth yield surface. In this study the model is extended for materials exhibiting a purely elastic response under a particular state of stress state, named an elastic boundary surface, whilst they also exhibit a smooth elastic-plastic transition. A damage evolution is also described by incorporating a damage function for the conventional model. The applicability of the model to the cyclic plasticity phenomena observed for the cyclic stresses below the yield stress is verified through the comparison with the experimental data.

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Constitutive equations have to be formulated in an identical form independent of coordinate systems by which they are described so as to be independent of the superposition of rigid body rotation. This fact is attained by describing rate variables in terms of rate tensors with objectivity in constitutive equations in rate form. Besides, a plastic strain rate is derived by substituting the plastic flow rule into the consistency condition given as the material-time derivative of yield condition. In this note a general corotational rate tensor in arbitrary order is first shown and it is verified that rate variables in the material-time derivative of yield function involving arbitrary tensors can be replaced to the corotational rate tensors.

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Recent advances in miniaturization and high-accuracy measurement techniques have allowed us to measure the mechanical properties at the nanometer scale. Nanoindentation has been widely used because of its applicability under ambient conditions. Unstable displacement burst, that is abrupt growth of indent depth after homogeneous elastic deformation observed in crystalline materials, is one of the unique plastic deformation (nanoplasticity). In the present paper, we perform a series of atomistic simulations of nanoindentation in single crystalline Al and Cu to analyze the critical state for dislocation nucleation and interaction between dislocations beneath the indenter. Referring Hertzian solution based on the isotropic linear elastic theory, we attentively disscuss the anisotropic effect and the nonlinear behavior under nanoindentation. Consequently, it is found that incipient yield process is strongly related to the triaxial stress state created beneath the indenter, and that energetically unfavorable interactions accompanied with cross slip induce the formation of prismatic dislocations.

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The superior compressive property of double layer honeycomb core sandwich panel has been studied from compressive tests of double layer aluminum honeycomb core sandwich panel. In the previous paper, the effect of core height was reported. In this paper, the effect of cell wall thickness was clarified as follows : 1) The compressive strength of the laminated panel depended on the highest one in single layer panels that were an equivalent cell wall thickness and an equivalent core height to each layer of laminated panel respectively. 2) The absorption energy of the laminated panel was superior to the total absorption energy of single layer panels that were an equivalent cell wall thickness and an equivalent core height to each layer of laminated panel respectively. 3) The specific compressive strength and specific absorption energy of the laminated panel was inferior to those of single layer panel that was the higher cell wall thickness in the laminated panel and an equivalent core height to the total core height of laminated panel.

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