Shock wave profile effects on dynamic failure of tungsten heavy alloy

It is well established that dynamic fracture or spall is a complex process strongly influenced by both the microstructure and the loading profile - the shape of the shock wave as a function of time - imparted to the specimen. For ductile metals it has been observed that the spall response is highly dependent on the pulse shape in addition to the peak stress. Here tungsten heavy alloy (WHA) specimens have been subjected to a shock wave loading profiles with a similar peak stress of 15.4 GPa but varying duration. Contrary to the strong dependence of strength on wave profile observed in ductile metals, for WHA, specimens subjected to significantly different wave profiles exhibited similar spall strength. Post mortem examination of recovered samples revealed that dynamic failure is dominated by brittle cleavage fracture, with additional energy dissipation through crack branching in the more brittle tungsten particles. Overall, in this brittle material all relevant damage kinetics are equally supported by both loading profiles considered, and the spall strength is shown to be dominated by the shock peak stress, independent of loading profile. © The Society for Experimental Mechanics Inc. 2014.