Models for mixed mode damage paths in shock loaded tantalum

Abstract
Recent work [1] on recovered tantalum gas gun and HE driven samples has shown that incipient damage forms a path with a well defined roughness exponent. The path involves regions of localized plastic flow, in the HE driven case, and localized flow regions between voids, or “mixed mode”, in the gas gun case. The localized plastic flow can be diffuse or very localized into a “micro shear band.” The roughness property is an affine statistical scaling with a different scaling ratio between the shock and transverse directions. In this work, we model the scaling properties of the mixed mode damage paths with models of shear localization between voids. These models involve a bifurcation condition for necking down localization, similar to that of Thomason, and a “micro shear band” condition. The localization condition is driven by both pressure and shear, hence, the name “mixed mode.” Monte Carlo simulations of the damage path will be conducted using these models to test them for the affine scaling.