Identification and comparison of different constitutive laws for high speed solicitation

Abstract
This paper deals with a methodology for the identification of constitutive laws for metallic materials under dynamic loading at high strain rates. Different constitutive elastoplastic behaviors are compared to represent several materials such as 42CD4 steel or aluminum alloy A2017T3. The classical radial return algorithm is used to integrate the elastoplasticity law with a mixed isotropic/kinematic hardening. The theory has been used to implement the constitutive law in Abaqus/Explicit Vumat subroutine. In the second part we present the different types of elastoplastic hardening laws such as Johnson-Cook, modified Johnson-Cook, Zerilli-Armstrong or Simo. We discuss the different forms of the laws and their taking into account of strain rates, speed and temperature. The iterative procedure for the identification uses an experimental set of parameters (from a Taylor impact test) which are compared with an other set of numerical values. The method to converge to the optimal solution uses a combined Monte-Carlo and Levenberg-Marquardt algorithm. The study ends with a comparative discussion about the laws and the problems encountered during their identification for two materials: a 42CD4 steel, and an aluminum 2017T3.