Deformation, Fracture and Explosive Properties of Reactive Materials

A range of techniques has been developed for studies of the behavior of explosives when impacted and for recording their strength, failure and ignition properties. They include a drop-weight facility with transparent anvils, an instrumented drop-weight machine, a miniaturized Hopkinson bar system for high rate of strain property measurement, laser speckle for studies of deformation and fracture of PBX's, an automated system for analysing speckle and moire records, and a heat sensitive film technique for recording the position and temperatures of hot spots. The report describes impact tests using transparent anvil drop-weight apparatus. It discusses the latest developments and recent applications with laser speckle and moire research. We now have the ability to combine these high spatial resolution techniques with high speed photographic recording. Impact on 2-D composite disc samples shows the importance of 'liner' materials in reducing impact stresses. The application of laser speckle photography to measure the in-plane displacement fields resulting from the compression loading of cylindrical grains of inert solid propellants for guns is discussed. Microstructural studies on the failure surface of PBX's are presented. Results on a photographic study of shock-induced cavity collapse of both inert gels and reactive materials are presented.