Effect of Shock Precompression on the Dynamic Fracture Strength of 1020 Steel and 6061-T6 Aluminum

Abstract

In impact-produced spall fracture, a material undergoes drastic dynamic precompression immediately prior to the time of fracture. In this paper a technique is described for varying the precompression stress wave magnitude σc relative to the magnitude σr of the rarefaction wave, which produces the spall, in the range of σc/σr≥1. The method is used to determine the spall strength of 1020 steel and 6061-T6 aluminum following precompression stress amplitudes up to 120 kbar. The results show that for these two materials neither the spall strengths nor the modes of fracture initiation and crack growth depend on the amount of precompression in the range attained in these experiments.