Warm forming simulations of Al-Mg alloy sheet using a viscoplastic model and advanced yield functions

Al-Mg alloys have the properties of anisotropy, temperature softening and strain rate hardening in warm forming conditions. The former could be modeled by an advanced non-quadratic yield function. The rate-dependent characteristic could be modeled by viscoplastic constitutive models. Up to now, few investigations have combined a viscoplastic model with advanced yield functions for warm forming simulation, especially by an implicit finite element (FE) program. In this investigation, the warm forming simulation of AA5182-O alloy was presented via Abaqus/Standard, considering the viscoplasticity and anisotropy. The established viscoplastic model could well reflect the nearly rate-independent initial yield stress of the selected material, and its parameters could be easily calibrated. The numerical implementation of the viscoplastic model associated with Yld2000 and Yld2004 yield functions was carried out using an implicit integration algorithm, and the algorithmic tangent was deduced. Results accordance between the simulation and experiment, including warm uniaxial tension test and warm deep drawing test of AA5182-O, showed the rationality of the established material model and the corresponding implicit implementation scheme.