The objective of the analysis is to find out to what extent the thermal stress in a bonded assembly could be reduced as a result of employing a compliant bonding layer with an interfacial compliance varying along the assembly. It has been determined that by employing such a layer one can achieve in an assembly of any size a low stress level and the same type of the stress distribution that takes place in a small size assembly: the interfacial shearing stress changes linearly along the assembly and the normal stresses in the adherends follow a parabolic law. We have encountered a rather paradoxical situation taking place in an assembly with an optimized longitudinal distribution of the interfacial compliance (that increases in accordance with a parabolic law from a next-to-zero value in the mid-portion of the assembly to large values at its ends): the maximum stress in such an assembly is lower than the maximum stress in an assembly with a highly compliant bonding layer of constant compliance of the same magnitude as the (high) compliance at the ends of an assembly with an optimized compliance. We conclude that this situation occurs because the peripheral interfacial displacements in an assembly with the varying compliance are reduced owing to the stiffer (less compliant) mid-portion of the bonding layer.

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A numerical simulation was presented to discuss the microscopic damage and its influence on the strength and energy-absorbing capability of short-fiber reinforced plastic composites. The dominant damage includes matrix crack and/or interfacial debonding, when the fibers are shorter than the critical length for fiber breakage. The simulation addressed the matrix crack with a continuum damage mechanics (CDM) model and the interfacial debonding with an embedded process zone (EPZ) model. Fictitious free-edge effects on the fracture modes were successfully eliminated with the periodic-cell simulation. The advantage of our simulation was pointed out by demonstrating that the simulation with edge effects significantly overestimates the dissipative energy of the composites. We then investigated the effect of the material microstructure on the fracture modes in the composites. The simulated results clarified that the inter-fiber distance affects the breaking strain of the composites and the fiber-orientation angle affects the position of the damage initiation. These factors influence the strength and energy-absorbing capability of short fiber-reinforced composites.

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In this study, a hybrid method is developed. The hybrid method utilizes discrete element method (DEM) and finite element method (FEM) simultaneously, which is used for simulation of impact problems. A disk particle modeled by DEM, collides onto a beam modeled by FEM. Numerical analyses are elaborated to examine behaviors of elements near the contact area and stress evolution beneath the contact surface. Through comparing the numerical results obtained by the hybrid method with LS-DYNA calculation results and the analytical solution by Hertz's contact theory, the accuracy of the hybrid method is evaluated.

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We researched the characteristics of the Pt-Hf-Zr-Ni thin film amorphous alloys for precise optical glass lens mold. The five Pt-Hf-Zr-Ni thin film amorphous alloys having various alloy composition were prepared. Desired characteristics for the glass lens mold were researched. Thus, the Pt₅₁Hf₂₀Zr₁₇Ni₁₂ sample was found as the candidate material for the glass lens mold. This sample showed the crystallization temperature of 994 K, the fractured stress of 1.01 GPa and anti-sticking properties to molten glass. However, since the Pt₅₁Hf₂₀Zr₁₇Ni₁₂ sample exhibited insufficient oxidation resistance, it is necessary to inhibit oxidation with protective coating in order to apply this sample to glass lens mold. Moreover, the Pt₅₁Hf₂₀Zr₁₇Ni₁₂ sample fabricated using alloy target could be cut to taperd shape by the single crystal diamond tools without tool wear.

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The interface stress distributions in scarf adhesive joints with dissimilar adherends under static tensile loadings are analyzed using two-dimensional and three-dimensional finite element calculations. The effects of the adherends and adhesive Young's modulus, the scarf angle and the adhesive thickness on the interface stress distributions are examined. In addition, the joint strength is predicted using the interface stress distributions based on the maximum principal stress theory. It is found that when the scarf angle is around 60°, the singular stress at the edges of the interfaces is minimum in the 3-Dimensional FEM calculations. Furthermore, it is noticed that the strength of the joints with dissimilar adherends is smaller than that of the joints with similar adherends. For verification of the FEM calculations, the strains in the adherends and the joint strengths were measured in the experiments. The measured strains are in fairly good agreement with those obtained from FEM calculations. Also, the measured joint strength is fairly consistent with the calculated results.

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