Precursor decay in 1060 aluminum

Pressure profile measurements for shock waves in 1060-0 aluminum show a decaying elastic precursor. Its amplitude diminishes from 1.06 kbar at a propagation distance of 1.38 mm to 0.53 kbar at 9.68 mm. Combining these precursor amplitudes with earlier measurements by others yields a curve of amplitude vs distance which runs from 1.38 to 25 mm. Decay rates obtained from this curve yield values of dislocation density 3–80 times greater than those inferred from etch-pit counts on polished surfaces. Rise times in the elastic precursor are greater at large distances than at small, suggesting effects of viscosity.