Cavitation instabilities in amorphous solids*

Amorphous solids are known to fail catastrophically. As a result, studying the response of amorphous solids to mechanical deformation is of great interest. Recent experiments suggest that fracture in amorphous solids occurs via nano-scale cavitation. In numerical simulations, the studies of plasticity in amorphous solids typically employ constant-density shear deformation. Upon shear deformation, amorphous solids undergo extensive plasticity via a yielding transition. Under constant-density shear deformation, one usually doesn't observe any significant density inhomogeneities, let alone fracture. To overcome this, we explore the elasto-plastic response of the amorphous solids to athermal quasistatic expansion(AQE) in numerical simulations. We find that under AQE, the solid undergoes a yielding-like transition that leads to formation of cavities in the solid. On further loading, the cavities grow and merge, ultimately resulting in complete fracture of the solid. Via this study, we highlight some similarities & differences between plasticity under shear and plasticity under volume expansion.