A fully 3D nonassociated anisotropic plasticity considering nonlinear strength differential effect; numerical implementation and applications

In the context of metal alloys forming, reliably predicting plastic behavior in the presence of anisotropy and tension-compression asymmetry remains a significant challenge, particularly due to the strength differential effect (SDE). In the present work, a new three-dimensional, non-associated flow rule (non-AFR) capable of representing the nonlinear strength differential effect (NSDE) is proposed. The model simultaneously incorporates anisotropy, mixed hardening, isotropic and kinematic, and the NSDE within a fully 3D framework, making it suitable for the complex loadings encountered in the automotive and aerospace industries. The non-linearity of the SDE is due to its dependence on hardening. Furthermore, a simple analytical identification of the model is proposed in 3D cases and thin sheets. The formulation has been developed for the implementation into finite element analysis codes. The model was validated using anisotropic experimental data on two aluminum alloys. Finally, identification of considered material, validation with numerical test and springback test, highlight the robustness and relevance of the proposed model.