Spall fracture of beryllium under shockwave loading

We present investigations of beryllium spall fracture with samples of dimensions o 65×7 mm, which were made via vacuum hot pressing. Samples were loaded at normal incidence by a detonation wave of the explosive charge of TG 5/5 composition, 7, 14 and 30 mm in thickness, which gave shockwave stresses of 21-25 GPa within the sample. Spall fractures formed as the sample unloading at an air gap. A velocity profile was measured at the free boundary using VISAR laser interferometer, a spall layer thickness was measured with two-frame impulse X-ray radiography, and the shockwave profile was measured via a manganin-based gauge in a fluoroplastic base in the course of deceleration of a spall layer and of a basic part of beryllium. Hugoniot dynamic yield strength (YHE) and spall strength (σP) were measure as 0.69-0.73 GPa and 0.85±0.03 GPa, respectively, at a strain rate of e ~104 s-1 in the unloading part of the incident pulse. A weak dependence between the spall layer thickness and HE layer thickness was recorded...