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Bulk metallic glasses (BMGs) have a variety of excellent properties compared with the majority of conventional crystalline alloys. However, they exhibit limited global plasticity at room temperature because of shear banding. Several methods have been proposed to improve the limited ductility of BMG; one method is the homogeneous distribution of crystalline particles. However, our understanding of the interaction between the crystalline particles and shear bands (SB) is not sufficient. Here, we performed molecular dynamics (MD) simulations of mode II deformation of a notched BMG plate and BMG plates containing one nano-crystalline particle ahead of the notch bottom. To compare the effect of crystalline particle size on the resistance to SB propagation, we used the J-integral. By comparing J–R curves and the deformation behavior of the BMG plates with and without nano-crystalline particles, we found that the resistance to shear banding is efficiently improved by introducing crystalline particles with sufficient size, compared to the SB width.

The high residual stress in a resin-molded electronic package sometimes makes the electronic functions unstable. Therefore the residual stress in electronic packages, especially on the top surfaces of semiconductor chips, should be evaluated. The objective of this study is to present a simple method for evaluating residual stress in resin-molded semiconductor chips using a combination of experimental and numerical methods. The actual residual stress of the packaging process was measured by using test chips that included piezoresistive gauges. A linear thermoelastic finite element analysis was then carried out using a three-dimensional model. The finite element analysis was performed under a stress-free temperature determined by the temperature dependence of the residual stress, which was experimentally measured by using the piezoresistive test chips. The measured residual stress using the test chips agreed well with the results of the finite element analysis. It was therefore confirmed that the present evaluation method, combining experimental and numerical methods, is reliable and reasonable.

Microdefects, such as dislocations and macrocracking, should be controlled during crystal growth to obtain high-quality bulk single crystals. Research activities related to thermal stress analysis during crystal growth, the cracking of single crystals induced by thermal stress, and dislocation density estimation during crystal growth are reviewed in this chapter. The effect of growth direction on the quality of single crystals is clarified based on three-dimensional thermal stress analysis of crystal anisotropy. The stress component governing the cracking induced by thermal stress and its critical values are obtained from the thermal stress analysis of experimental data on crystal cracking induced by thermal stress. The Haasen–Alexander–Sumino model, a dislocation kinetics model in which creep strain rate is related to the dislocation density as well as stress components, is applied to the quantitative estimation of dislocation density in semiconductor single crystals.

The evaluation of a fracture in a thin plastic material layer constrained by hard materials is important in relation to the structural integrity of adhesive joints and composite materials. It has been reported that the fracture toughness of a crack in a ductile adhesive joint depends on the bond thickness. The stress field and the damage zone ahead of a crack tip in a thin modified epoxy resin layer constrained by hard bodies is analyzed using the Gurson model in conjunction with the finite element method. The size of the damage zone ahead of a crack tip increases with the decrease of bond thickness from 2.0 mm to about 0.7 mm. After this point it slightly decreases with the decrease of bond thickness less than 0.7 mm. In a very thin adhesive layer of less than 0.2 mm, the damage zone extends to the interface between the adhesive layer and the constrained body. This is similar to the microscopic observations of the damage zone ahead of a crack tip inside a thin adhesive layer of rubber modified epoxy resin constrained by aluminum adherends.

The objective of this study is to present a procedure based on the element-free Galerkin method (EFGM) for evaluating dynamic fracture parameters. The EFGM is one of the famous meshless methods. By using the EFGM, the first derivatives i.e. strain and stress for a structural analysis have continuity because of moving least square method (MLSM). When contours used for evaluating path independent integrals, such as the J-integral, are chosen, it can be regardless of the analyzed mesh. In fracture mechanic problems, the EFGM may be useful to calculate fracture mechanics parameters for crack propagation problems. In this study, half-round contours are applied to evaluate dynamic fracture parameter J-integrals. The center cracked plate subjected to tension with a Heaviside function which depends on time has been successfully analyzed and dynamic stress intensity factors have been evaluated by calculating the dynamic fracture mechanics parameter J-integrals. We have found that the EFGM can evaluate the fracture mechanics parameters appropriately and that fracture mechanics analyses of the EFGM using arbitrary contours was much easier than that of the FEM.

A significance of the effect of thermal inhomogeneity on evaluating stability of cracks in structure subjected to intense thermal loading is stressed. A risk of considerable underestimate of the crack-tip severity may be present if the temperature dependence of the material properties are not accounted for. The use of proper integral fracture parameter, T*, and the alternate parameters, Jθ′ and J′, are suggested for the present class of thermal fracture problems. Through numerical simulations of thermal crack problems, the use of these parameters and the significance of the effect are demonstrated.

We developed a computer program for estimating creep damage of piping. The finite element method is used for heat conduction and stress analyses. Thermal strain, creep strain and temperature dependence of material properties are taken into account in the stress analysis. The damage mechanics for creep is used to estimate the life of structural components which receive creep damage. We study the effects of piping size, creep characteristic of material and the modes of plant operation on the life of steam reformer furnace piping.