Molecular-dynamics simulations of two-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.