Computational anisotropic plasticity for high-rate forming applications Original Research Article

Constitutive models and solution algorithms for anisotropic elastoplastic material strength are developed for use in high-rate explicit multi-dimensional continuum mechanics codes. The constitutive modeling is posed in an unrotated material frame using the polar decomposition theorem. Continuous quadratic and discontinuous piecewise yield functions obtained from polycrystal simulations for metallic hexagonal-close-packed and cubic crystal structures are utilized. Associative flow formulations incorporating these yield functions are solved using various solution algorithms; explicit, semi-implicit and geometric normal return schemes are assessed for stability, accuracy and efficiency. Isotropic scaling (hardening) of the anisotropic yield surface shapes is included in the modeling. An explosive forming application involving large strain was selected to investigate the effect of using anisotropic materials. Axisymmetric two-dimensional forming simulations were performed for both crystal structures producing resultant formed shapes that are unique to the materialʹs initial yield anisotropy, and are distinct from isotropic results.