DISLOCATION MECHANISMS FOR SHOCK-INDUCED HOT-SPOTS

Crystal dislocations provide the ultimate source of localized damage e nhancement within solid materials, Vortices are the dislocation counte rparts within liquids and gases. For energetic crystals, tubular holes might run along the pre-existent dislocation line lengths and act as shock-induced ''in-situ'' hot spots. Beyond this consideration, nearly invisible clouds of dislocations are possibly generated at point defe cts or point defect clusters by the shear stresses at a shock front, M ultiple fine scale dislocation movements provide a mechanism for the s hock to move to a hydrostatic stress state. Interatomic or intermolecu lar separations of the order of critical reaction coordinate distances are achievable during the unit dislocation displacements --- without change in material volume. Such nanoscale dislocation predictions conn ect with microscale experiments in a number of cases where larger scal e ''defect'' considerations are involved. Dislocation pile-ups in slip band avalanches, often associated with cracking, account for very app reciable and localized heating that is deformation rate dependent. Com plex dislocation slip band interactions occur within the plastic zones of macroscopic crack tips to control the fracture toughness propertie s of energetic and related materials.