金属ガラスの動的変形解析における欠陥密度と温度の影響

抄録

Bulk metallic glass (BMG) is the advanced material that has no crystal structure and shows peculiar mechanical properties. Currently, the exact description on the shear band forming process and destruction behavior of BMG is not established yet. Because of its inherent characteristics, BMG is expected to be applied in various fields, for example, aerospace structures, sensing devices and so on. In this study, the inhomogeneous defect theory, which was developed by Shibutani et al. in the basis of the free volume theory and the Drucker-Prager yield criterion, was incorporated into the explicit FEM code dyna3d to evaluate dynamic deformation behavior of BMG. The experimental data of tension / compression tests of BMG imply that the specimen temperature greatly rises under the shear band forming process. Here, to examine the effects of the initial dispersion of defect density and the temperature change, a series of numerical simulations for the deformation and destruction of BMG under dynamic loading condition was carried out by varying the standard deviation of initial defect density and by taking the adiabatic temperature change into consideration. The initial geometrical imperfection and the strain-rate condition were also varied. As a result, for example, it was found that the initial yield stress decreased with the increase of standard deviation of initial defect density.