Full-Field Crystal Plasticity Modeling of \( \mathbf{\{ 1\,0\,\overline{1}\, 2\}} \) Twin Nucleation

Historically, the ability of crystal plasticity to incorporate the Schmid’s law at each integration point has been a powerful tool to simulate and predict slip-induced localization at the single and polycrystal levels. Unfortunately, this remarkable capability has not been replicated for materials where twinning becomes a noticeable deformation mechanism. The challenge resides mainly in the biased regional lattice transformation associated with twin formation in defiance of its obedience to threshold stress. Inspired by results from micromechanics, digital image correlation, and molecular dynamics, we developed an explicit twinning nucleation criterion based on hydrostatic stress gradient and volume fraction of twin inside a grain. Characteristic twin spacing parameter is used as a function of twin height to determine site-specific nucleation points in the case of multiple twins. This approach offered a good reproduction of the microstructure evolution and autocatalysis phenomenon as affected by twinning in a tricrystal system.