PARTICULATION OF METALLIC JETS UNDER HIGH-STRAIN RATE

High-speed metallic jets are squeezed out of the conical cavities in a metallic block when loaded with shock waves. The particulation studie s on these jets, which elongate under a strain rate of the order of 10 (4)-10(5) s-1, have been carried out theoretically as well as experime ntally. The synchro-streak technique (SST) has been used to measure th e unparticulated jet distance (UPJD). The time of particulation calcul ated from the UPJD has been found to be equal to the total of the coll apse time and the stretching time. It has been found that as the angle of conical cavity increases, the jet diameter and the particulation t ime increase, whereas the jet tip velocity and existing strain rate de crease. From the experimentally measured jet diameter the time of part iculation has also been calculated by the Hirsch approximation. This t ime period is in close agreement with the particulation time calculate d by the authors. From the measured jet diameter and jet length, the m ass of the jet and the thickness of the block material squeezed into t he jet have been estimated. A comparative study on aluminium and coppe r jets has also been conducted and it has been observed that for the g iven explosive metal system the jets produced by aluminium are solid a nd coherent as compared to those produced by copper.