Effect of Poisson's ratio on crack tip fields and fracture behavior of metallic glasses

Abstract

A study of the effect of Poisson's ratio on the stationary mode I crack tip fields in amorphous alloys is conducted. Finite element simulations under plane strain, small scale yielding conditions are performed with a Mohr-Coulomb based constitutive model that accounts for pressure sensitivity of plastic flow as well as the localization of plastic strain into discrete shear bands. Simulations are also performed with von Mises and Drucker-Prager constitutive models. While the Poisson's ratio does not alter the crack tip fields significantly when the material obeys these two models, it has a marked influence in the Mohr-Coulomb case with softening. A higher Poisson's ratio reduces the extent of plastic zone and plastic strain levels in front of the notch tip as well as that within the simulated shear bands around the notch root at a given level of stress intensity factor. The implications of these observations on toughness of metallic glasses are discussed.