Incorporation of an anisotropic (texture-based) strain-rate potential into three-dimensional finite element simulations

An anisotropic (texture-based) strain-rate potential is incorporated directly into a finite strain formulation in the form of an elastoplastic constitutive model. The technique is based on the Taylor theory of crystal plasticity and thus takes texture-induced variations in properties into account. A three-dimensional user material (UMAT) subroutine has been developed and implemented in the commercial finite element code ABAQUS. A stress updating integration algorithm is used in conjunction with the constitutive model and with the backward implicit Euler method. An explicit expression is derived for the consistent tangent modulus. The cup drawing of textured Al-alloy sheets was simulated using this code in conjunction with the UMAT subroutine. The full geometry of drawing is accounted for in the simulations. Friction effects and thickness variations are also taken into consideration. Reasonable agreement is observed between the predicted and measured ear profiles.