This paper describes stochastic analysis of microscopic stresses in a fiber reinforced composite material caused by a random variation of an elastic property of a component material. The microscopic stress takes an influence of not only the microscopic random variation but also a macroscopic condition such as constant stress or strain. From this reason, the influence of the microscopic random variation on the microscopic stresses must be analyzed with using a multiscale analysis method. In order to investigate the stochastic characteristics of the stresses, the homogenization method and the Monte-Carlo simulation method are employed in this study. With numerical results, the stochastic characteristics of the microscopic stress caused by a random variation of an elastic property in component materials of a unidirectional fiber reinforced component material under constant macroscopic stress or strain condition are discussed.

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This paper describes a pushing cut process of a piled-up polycarbonate (PC) sheet. Resin laminated sheets such as thermal insulation films or liquid crystal panel are recently processed by using a wedge indentation due to its production efficiency and its precision cutting. However, deformation of laminated resin sheet is often unstable during cutting or creasing process, and its dynamic behavior is not sufficiently revealed. In this work, the cutting line force of several center bevel blades was measured by load cells, and the cutting deformation of the PC sheet was observed by a CCD camera in order to reveal the effect of blade tip profile and the contact condition. The deformation flow in the side view of the PC sheet was observed with respect to the blade indentation by varying the blade tip angle, the feed velocity and the surface contact condition.

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In this paper, stress intensity factors for a two-dimensional interface crack under polynomial distribution of stress are considered. The problem is formulated as a system of hypersingular integral equations on the idea of the body force method. In this analysis, unknown body force densities are approximated by the products of the fundamental densities and power series; here the fundamental densities are chosen to express singular stress fields due to an interface crack under constant distribution of stress exactly. The stress intensity factors of a 2D interfacial crack under polynomial distribution of stress are expressed as formulas for the reader's convenience with the varying polynomial exponent n. The exact expressions of crack opening displacements are also indicated.

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A modified extended Tersoff interatomic potential function is proposed to simulate environment-assisted crack propagation behavior. First, the physical properties of Si, O₂, H₂, SiO₂, and H₂O were calculated by this modified function. It was confirmed that the calculated values agreed with the measured values very well. Next, the potential surface of the H₂O molecular transporting process to the crack tip of SiO₂ material was calculated by the same function. The relationship between the velocity of crack propagation "υ" and the stress intensity factor "K" was calculated based on this surface. The results agreed with the experimental results well. This simulation clarified that the crack velocity is controlled by the H₂O transporting process in both regions I and II of the "υ-K curve". In region I, H₂O molecules have physically limited access to the crack tip due to the small opening in the crack. This works as an energy barrier in transporting H₂O molecules. Due to the relatively large crack opening in region II, H₂O molecules have free access to the crack tip without any energy barrier. This difference makes a bend in the "υ-K curve" between regions I and II.

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