Microstructural effects in PBX 9501 damaged by shear impact

Various microstructural mechanisms have been suggested for ignition in explosives subjected to impact by low-velocity projectiles. In this study, the effects of shear on the microstructure of PBX 9501 are described. The pseudo two-dimensional, shear-impact experiment, previously employed by Asay, et al. to dynamically study strain localization, is engaged to create shear damage. Impact is achieved by utilizing a gas gun projectile to drive a plunger, which is in contact with the explosive. Post-test microstructural analysis corroborates the observations of other researchers using different diagnostics. Observed features include evidence of shear displacement, the formation of a wedge structure, and reaction in open cracks emanating from the high shear region of the sample. This study also contributes insights concerning the behavior of HMX particles subjected to shear stress.