Molecular-level investigation on the spallation of polyurea

We used molecular dynamics (MD) simulations to investigate the nanoscale mechanism associated with the spallation of polyurea, which allowed us to test some assumptions commonly made in the interpretation of similar experiments on the macroscale. The spall strength was computed by following two methods: (i) The indirect method (from the free surface velocity history—commonly used in experiments) (ii) A direct method (from the atomic stresses in the spall region—accessible only in MD). Our results show that the spall strength computed from the direct method is consistently higher than that obtained from the indirect method.