Comparison of experimental and calculated elastic-plastic wave profiles in LiF

Abstract

Precursor decay in pure LiF has been examined using a laser interferometer technique to measure particle velocity at the rear surface of specimens with thicknesses of about 1.1 and 3.5 mm. For an initial impact stress of about 2.5 GPa (25 kbar), the measured precursors were found to be essentially sharp shocks with rise times on the order 1–2 ns and with amplitudes of 0.25 and 0.24 GPa, respectively. The complete wave profiles measured experimentally have been fit with a characteristic code, employing the method of shock fitting. Good agreement between experimental and calculated results is obtained using a constitutive model based on the nucleation of dislocations at the shock front and subsequent expansion in the form of circular loops.