Crystal Failure and Crack Formation During Plastic Flow

Atomic Force Microscopy (AFM) of molecular crystals subjected to impact or shock has shown increasing lattice and molecular damage with increasing levels of plastic flow. While AFM measures only surface distortions, evidence exists showing that the molecular and lattice distortions persist deep within the crystal interior. This evidence of lattice damage has been used to provide a physical model of lattice softening and eventual failure during large plastic deformation due to impact or mild shock. For a simple geometry, the onset of crystal failure and crack trajectory during impact is determined and compared with experiment.