EFFECT OF CONSTITUTIVE MODELS ON STEADY-STATE AXISYMMETRICAL DEFORMATIONS OF THERMOELASTIC VISCOPLASTIC TARGETS

We study the steady state axisymmetric deformations of a thick target being penetrated by a rigid cylindrical penetrator with a hemispherical nose and use three different constitutive relations, namely, the Litonski-Batra flow rule, the Bodner- Partom flow rule, and the Brown-Kim-Anand flow rule, to model the thermoelastic-viscoplastic response of the target. Each of these constitutive relations uses an internal variable to account for the microstructural changes in the body. The three flow, rules are calibrated to give virtually identical effective stress-logarithmic strain curves during the overall adiabatic plane strain compression of a block of the target material deformed at an average strain rate of 3300 s-1. It is found that the three constitutive relations give nearly the same value of the resisting force acting on the penetrator, temperature rise of material particles in the vicinity of the target penetrator interface, and other macroscopic measures of deformation, such as the effective stress and logarithmic strain rate.