Mesh-free Galerkin simulations of dynamic shear band propagation and failure mode transition

A mesh-free Galerkin simulation of dynamic shear band propagation in an impact-loaded pre-notched plate is carried out in both two and three dimensions. The related experimental work was initially reported by Kalthoff and Winkler (1987), and later re-examined by Zhou et al. (1996a,b), and others. The main contributions of this numerical simulation are as follows: (1) The ductile-to-brittle failure mode transition is observed in numerical simulations for the first time; (2) the experimentally observed dynamic shear band, whose character changes with an increase of impact velocity, propagating along curved paths is replicated; (3) the simulation is able to capture the details of the adiabatic shear band to a point where the periodic temperature profile inside shear band at μm scale can clearly be seen; (4) an intense, high strain rate region is observed in front of the shear band tip, which, we believe, is caused by wave trapping at the shear band tip; it in turn causes damage and stress collapse inside the shear band and provides a key link for self-sustained instability.