SHOCK ATTENUATION IN SOLID AND DISTENDED MATERIALS

Abstract : Good methods exist to estimate shock response of certain elastic- rigid foams at very high pressures when no forerunner is present, and at very low pressures when no locking wave is present. For the intermediate region of pressure (approximately 0.1 to 6 kbar), when both waves are present and of the same order of magnitude, predictions are less reliable and values forecast of pressure in this region based on general theories are too high. From considerations of pressure wave shape it is believed that this anomaly may be related to the porous nature of the foam. The investigation experimentally measured peak pressures transmitted to a steel wall to about 6 kbar, found conditions for double-wave structure, and observed wave shapes produced by impacts carrying momentum densities in the range 0.6 to 30,000 taps in 0.7 to 1. 4 g/cc aluminum, 0.67 g/cc polyurethane, 1.1 g/cc beryllium, 1.1 to 1.7 g/cc graphite, and 1.0 g/cc silica foam.