Improved Modelling of Bauschinger Effects in Plastic Flow

The research and development proposed here closes the gap on an important area of simulating material behavior. In particular, anisotropic models of the Bauschinger effect have been neglected in the development of hydrocodes for the simulation of viscoplastic behavior, in spite of its important to both impact and penetration phenomena. The Bauschinger effect is fundamental to the proper simulation and design of ballistic weapons and defenses, space structures, and many other critical metal allow structures subject ot impacts. The proposed work will demonstrate the feasibility of implementing a new model of the Bauschinger effect. The new viscoplastic constitutive model will be based on well established internal variable representations of nonlinear kinematic hardening which properly account for the rate and temperature dependence, large straing kinematics, and suitable corotational stress rate. The model will be implemented using an existing Lagrangian finite element package, and will be verified by comparing simulation predictions with experimental results for several common experimental configurations.