Analysis of Crack Opening Behavior in Amorphous Metal (Comparative Study of Atomistic and Elasto-Viscoplastic Continuum Model)

Abstract

A large-scale molecular dynamics simulation on an atomistic model and an elasto-viscoplastic finite element analysis on a continuum model are carried out to study deformation field near a crack tip in amorphous metal. The atomistic model, in which Finnis-Sinclair type potential for iron is assumed as interatomic potential, is generated using heating-quenching simulation. The parameters in strain-dependent elasto-viscoplastic constitutive law for the continuum model are determined using a uni-axial tensile test for the atomistic model of amorphous metal. The results for the crack problem using the atomistic model and the continuum model are compared each other. The shape of crack front, strain distribution and stress distribution around the crack tip, increase of crack tip opening displacement and crack growth are examined, and FE results for the continuum model agree with MD results for the atomistic model. However, the continuum model can depict only averaged description of the atomistic model. In the atomistic model, it is observed that the highly deformed region consists of atomistically localized deformation. The atomistic simulation is indispensable to reveal the microscopic structures and deformation mechanisms.