Finite element analysis of compressive deformation of bulk metallic glasses

Abstract

Finite element analysis of a stress-overshoot phenomenon in a Pd-based bulk metallic glass was carried out using a fictive stress model in conjunction with the Maxwell viscoelastic model under uniaxial compression. The overshoot results from non-linear viscoelasticity in the glass transition region, under deformation at constant strain rate. The friction effect between a cylindrical workpiece and a die was shown to produce mainly three stress-concentration sites, which play an important role in creating free volume. These sites give rise to a redistribution of the structural disordering state inside the workpiece, and lead to a change of the average stress blunt. Once inhomogeneous deformation occurs during the development of the stress peak at the initial stages under high strain rates (5 × 10 −3–2.2 × 10 −2 s −1), the effective stress distribution within the workpiece becomes narrow and the deformation homogeneity is recovered in the ensuing steady state flow.