Large dilatational hyperelasticity of glasses en route to cavitation failure

TL;DR

This study reveals that glasses exhibit a hyperelastic response with micro-cavity formation under high stress triaxiality, leading to cavitation failure, with behaviors consistent across different glass types.

Contribution

It uncovers the large dilatational hyperelastic behavior of glasses near failure and links micro-cavity formation to cavitation, contrasting with low stress triaxiality responses.

Findings

Glasses show hyperelastic response with micro-cavities at high stress triaxiality.

Micro-cavities can be irreversible and act as failure nucleation sites.

Behavior is universal across different glass formers.

Abstract

Materials deform elasto-plastically and fail under various loading conditions, typically quantified by the stress triaxiality, which is the ratio between the dilatational (hydrostatic) stress and the deviatoric (shear-like) one. We show that the elasto-plastic deformation of glasses approaching failure qualitatively differ for large and small stress triaxiality levels. Specifically, in the former limit, glasses reveal a strong hyperelastic (nonlinear elastic) response with minute plasticity, largely independently of the quenching rate across the glass transition. Yet, glassy disorder gives rise to significant elastic (reversible) nonaffine deformation, accompanied by the formation of micro-cavities. A small fraction of the latter is irreversible, i.e., survives unloading prior to the onset of failure, and may serve as nucleation sites for failure in the form of large-scale cavitation, involving a topological transition accompanied by the formation of an internal free surface, upon which the glass loses a significant fraction of its load-bearing capacity. These results are contrasted with glass behavior in the limit of vanishing stress triaxiality and their universality across different glass formers is demonstrated. Finally, the implications of our findings for understanding glass deformation and failure under realistic stress conditions are discussed.