Experimental validation of detonation shock dynamics in condensed explosives

Abstract

Experiments in the HMX-based condensed explosive PBX-9501 were carried out to validate a reduced, asymptotically derived description of detonation shock dynamics (DSD) where it is assumed that the normal detonation shock speed is determined by the total shock curvature. The passover experiment has a lead disk embedded in a right circular cylindrical charge of PBX-9501 and is initiated from the bottom. The subsequent detonation shock experiences a range of dynamic states with both diverging (convex) and converging (concave) configurations as the detonation shock passes over the disk. The time of arrival of the detonation shock at the top surface of the charge is recorded and compared against DSD simulation and direct multi-material simulation. A new wide-ranging equation of state (EOS) and rate law that is constrained by basic explosive characterization experiments is introduced as a constitutive description of the explosive. This EOS and rate law is used to compute the theoretical normal shock velocity, curvature relation of the explosive for the reduced description, and is also used in the multi-material simulation. The time of arrival records are compared against the passover experiment and the dynamic motion of the shock front and states within the explosive are analysed. The experiment and simulation data are in excellent agreement. The level of agreement, both qualitative and quantitative, of theory and simulation with experiment is encouraging because it indicates that descriptions such as the wide-ranging EOS/rate law and the corresponding reduced DSD description can be used effectively to model real explosives and predict complex dynamic behaviors.