[P2-02] FTMP-based Modeling and Simulations of HCP Mg Single Crystal
Extended usages of Mg and Mg alloys have been widely promoted to date, attempting to make the best use of their attractive properties, such as light weight, high specific strength, superior recyclability and excellent bio-compatibility. Modeling attempts of Mg and Mg alloys, however, often meet difficulty in the treatments of the complex plasticity, mainly stem from their highly anisotropic slip systems and intricate activities of twinning. The present study aims at enhancing the feasibility of the recently-proposed model for deformation twinning based on FTMP (Field Theory of Multiscale Plasticity) toward extended applications to HCP Mg single crystal. The major updates of the model are two fold: one is the extension to efficient 3D simulations by introducing special computational schemes, while the other is to apply modified lattice rotation based on the rotational part of the incompatibility tensor. The twinning model with the modified lattice rotation is introduced in the hardening law in the FTMP-based crystalline plasticity framework, and is further implemented into a finite element code accommodated with the above new scheme. Deformation analyses are performed based on 2D/3D FEM for pure single crystal magnesium with HCP (hexagonal close-packed) structure, and critical comparisons are made with experimental data obtained under plain-strain compression in multiple orientations by Kelly and Hosford, particularly, with those exhibiting the unique stress-strain responses induced by deformation twinning, i.e., orientations A, E and F. Natural expression of twin-induced lattice rotation is attempted by introducing a modification based on the pure rotation part of the incompatibility tensor, spontaneously evolved during deformation. The modification is shown to allow autonomic transitions between slip and twinning modes, e.g., from twin-dominant stress response to that carried by slip, as in the orientations E and F by Kelly-Hosford.