Fracture of Shock Loaded Metal Samples with Artificial Protrusions on Free Surface

Abstract

The free surface fracture of aluminum and copper have been studied under conditions of the escape of a moderate-intensity shockwave from a sample, the variable duration of pressure pulses was 0.02, 0.2 and 1 µs. The free surface of samples contained 0.7–0.9 mm deep artificial wells and protrusions simulating (on a greater scale of M 10:1) the natural surface roughness retained upon mechanical processing. The pressure in a shock-wave pulse at the base of a protrusion was controlled within P = 10–53 GPa (i.e., below the melting region). Analysis of the free surface of post-loaded samples showed that, for certain loading degree of fracture of a free surface and metal ejection differs depending on parameters of a roughness of a surface. The amount of ejected metal and the size distribution of metal microparticles were quantitatively characterized using “soft collecting targets.”