Inertia Effect of Deformation in Amorphous Solids: A Dynamic Mesoscale Model

Abstract

Shear transformation (ST), as the fundamental event of plastic deformation of amorphous solids, is commonly considered as transient in time and thus an equilibrium process. Such non-inertia approximation however poses a major challenge when the deformation becomes nonequibrium, e.g., under the dynamic and even shock loadings. To overcome the challenge, this paper proposes a dynamic mesoscale model for amorphous solids that connects microscopically nonequibrium STs with macroscopically elastoplastic deformation. By controlling the applied strain rate and the ST’s activation time, we investigate the effect of ST’s inertia on deformation of amorphous solids. It is found that with increasing strain rate, the significant inertia effect facilitates the activation and interaction of STs, resulting in the earlier yield of plasticity and lower steady-state flow stress. We also observe that the externally-applied shock wave can directly drive the activation of STs far below the global yield and then propagation along the wave-front. These behaviors are very different from shear banding in the quasi-static treatment without considering the inertia effect of STs. The present study highlights the nonequibrium nature of plastic events, and increases the understanding of dynamic deformation of amorphous solids on mesoscale.

Keywords: Amorphous solids, Dynamic deformation, Inertia effect, Shear transformation, Mesoscale model