Time resolved and integrated diagnostics including high speed photography, mass and optical spectroscopy, and optical-radiometry used to study impact response of high explosives in far more detail than possible with conventional sensitiveness tests.
Abstract. The aim of the research reported here was to investigate the strain rate and temperature sensitivity of Rowanex 1100 Type 1A, a polymer-bonded explosive (PBX). The stress supported by this PBX at high rates of deformation (1750 ± 225 s −1 ) was found to be about an order of magnitude greater than that supported at low rates (0.015 s −1 ). Temperature was also found to have a large effect, with the strength of the material decreasing exponentially with temperature over the range studied (-60 to +60• C). The exponents for the decay of the PBX's strength with temperature at both low and high strain rates were the same within experimental error. So a temperature/strain rate shift factor could be determined and was found to be 31.2 ± 2.4 K/decade of strain rate.
The dynamic response of granular materials to an applied shockwave is of wide ranging importance. While the shock Hugoniot has been studied, the shock-release of granular systems has never been experimentally characterised. Here, we present a simple approach to such measurements and present a series of plate impact experiments providing release data for a well characterised dry sand. We discuss the origin of the release behaviour, which we support with further measurements on a weakly bound sandstone.
There is considerable interest in the high-rate compaction of brittle granular materials such as sand. However, the vast majority of studies focus on a single granular system, limiting our ability to make comparisons between materials to discern how granular structure manifests as bulk material response. Here, three different silica sands with similar grain size and shape are studied: we compare a rough quarry sand, a smoother-grained sand, and a sandy loam. Quasi-static compaction and planar shock loading responses are compared, and recovered samples analyzed. The combination provides information regarding the interplay between granular properties, loading conditions, and material response. We show that the fundamental grain-scale behaviour depends on loading conditions: At low strain rates compaction behaviour is dominated by grain morphology, and in particular, smoothness and particle size distribution. Under shock loading, grain rearrangement and force chain effects are suppressed, and the nature of inter-granular contact points, modified by the presence of moisture or fines, is most important. Furthermore, grain fracture under shock loading is substantially reduced with increasing moisture content
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