金属ガラスの自由体積モデルに基づく衝撃破壊解析

抄録

Metalic Glass, Free Volume Model, Impact Fracture, Shear Bands, Strain Rate DependencThe yield behavior of amorphous metals including the metallic glass shows intrinsic dependence on the hydrostatic stress, so that yield criterion models such as Mohr-Coulomb and Drucker-Prager are often used. Both the models can explain the asymmetry in the yield stress under uniaxial compression and tension loading conditions, however, the asymmetric angle of fracture surface is not able to determine based on any theoretical foundation. The free volume model is able to provide that foundation. Shibutani et al. proposed a new constitutive model for amorphous metals derived from some advanced free volume models and the flow rule using the Drucker-Prager yield function as a plastic potential and investigated the yield curves and the formation of localized shear bands with that model using the implicit static FEM code. In this study, the impact fracture of metallic glass was examined by implementing their constitutive model in the explicit dynamic FEM code DYNA3D with laying emphasis on the occurrence mechanism of the asymmetric angle of fracture surface and the strain rate dependence.