ANISOTROPIC VISCOPLASTIC CONSTITUTIVE MODELING FOR METALS AND APPLICATION TO THE TAYLOR IMPACT TEST

Abstract An anisotropic viscoplastic constitutive model was developed for the description of the high-strain rate behaviour of zirconium, a HCP metal that exhibits strength differential effects and strong anisotropic strain hardening. The evolution laws for the strength differential parameter and the anisotropy coefficients involved in the expression of the yield criterion were obtained based on numerical tests performed with a crystal plasticity model. The strain rate dependent parameters involved in the formulation were determined from results of dynamic in-plane tests performed on a high purity zirconium plate [9, 10] on a Split Hopkinson Pressure Bar (SHPB). Simulations of the Taylor impact test were conducted using the finite element code ABAQUS with the anisotropic viscoplastic model. The very good agreement between the simulated and experimental post-test geometries of the Taylor specimens in terms of major and minor side profiles and impact interface footprints shows the ability of the phenomenological model to capture the influence of twinning on texture evolution.