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The present study addresses a simplified topology optimization method to improve load bearing capacity. Topology optimization taking account of structurally nonlinear and complex behavior is an important topic from the viewpoint of mechanics. However, most methodologies require complex analytical derivation of sensitivity analysis and high computational cost to obtain the optimal solution. In light of this, we propose a practical design method employing the principal direction of Cauchy stress and the directional statistics, to improve load bearing capacity indirectly with much lower computational cost than those based on complex nonlinear structural analysis. Finally, we discuss setting of optimization problems, and demonstrate the accuracy and performance of the proposed method with a series of numerical examples.

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For improving the electrical efficiency of a hybrid car, relationship between microstructure and thermal properties of carbon nanotube, carbon fiber reinforced aluminum composites were examined as heat sink plate. In this study, influence of interfacial thermal resistance between fiber and binder, fiber diameter and binder volume fraction on thermal conductivity of the composites were examined. Firstly, in order to examine the effectivity for binding the fibers by the binder, the interfacial thermal resistance between fiber and binder was compared with that between fiber and matrix. In order to examine the influence of fiber diameter, the thermal conductivity of multi walled carbon nanotube preforms was compared with that of carbon fiber preforms. As the result, interfacial thermal resistance between fiber and binder was lower than that between fiber and matrix. Secondly, it was revealed that the larger fiber diameter leads to the higher thermal conductivity of the composite. Finally, the binder volume fraction was influenced by the microstructure so that the simply increasing and decreasing tendency was not found for thermal conductivity of the composites. By means of simulation for thermal conductivity, it was suggested that highly constricted fiberϩbinder part would deteriorate the thermal conductivity of the composites.

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