MOLECULAR-DYNAMICS SIMULATIONS OF 2-DIMENSIONAL MATERIALS AT HIGH-STRAIN RATES

The mechanical behavior of model two-dimensional materials is investigated by large-scale molecular-dynamics (MD) simulations on a massively parallel computer. Both a pair-potential and a model embedded-atom many-body potential are examined. A parallel MD algorithm is developed to exploit the architecture of the Connection Machine, enabling simulations of greater than 10(6) atoms. Adiabatic expansions and spallation experiments on both perfect crystals and granular solids are performed. It is demonstrated that a uniform adiabatic expansion is a good model for the spallation process. The spall strength is shown to be proportional to the logarithm of the applied strain rate. A dislocation-dynamics model is developed to explain the results, which also leads to predictions for the impact spallation experiments.