An Eccentric Ellipse Failure Criterion for Amorphous Materials

We proposed an eccentric ellipse criterion to describe the failure of amorphous materials under a combination of normal stress sigma and shear stress tau. This criterion can reflect a tension-compression strength asymmetry, and unify four previous failure criteria in the sigma-tau stress space, including von Mises criterion, Drucker-Prager criterion, Christensen criterion, and ellipse criterion. We examined the validity of the eccentric ellipse criterion in the tensile-shear failure regimes using the results from our atomistic simulations for two typical amorphous CuZr and LiSi, and recent tension-torsion experiments on metallic glasses. The predictions from the eccentric ellipse criterion agree well with these results from atomistic simulations and experiments. It indicates that this eccentric ellipse criterion is essential for the tensile-shear failure of amorphous materials.