Hydrocode Simulation of the Formation and Penetration of a Linear Shaped Demolition Charge Into an RHA Plate.

This report presents the results of a combined experimental and numerical investigation of the formation and penetration of a linear shaped demolition charge into a rolled homogeneous armor RHA plate. The demolition charge is composed of a mild steel liner, filed with castable Composition-B high explosive. The numerical computations were conducted before the experiments using the Lagrangian hydrocode EPIC92 and predict a jet tip free flight velocity of about 5.2 kmls at 12IL. However, observed jet tip free flight velocities of the linear shaped charge LSC range from 33 to 35 kms as determined from flash radiography, and 3.5 kms using a special electrical makewire circuit test fixture. The reason for the large discrepancy between the predicted and observed jet tip free flight velocities appears to be related to inaccuracies resulting from the highly distorted computational mesh in the collapsing liner. Using the automatic rezone feature in the EPIC94 version of the hydrocode results in the reduction of the jet tip velocity from 4.7 kms to 3.8 kms at 4 ps. However, computations beyond 4 ps were not possible due to numerical instabilities associated with requiring a vanishingly small integration time increment resulting from an equation-of-state instability. Penetration depths into two rectangular r, 2-in-thick 50. 8mm RHA plates measure 17 and 18 mm respectively, whereas the hydrocode simulation predictss greater penetration depth of 22.9 mm. The work attests to the importance of conducting experiments in order to verify baseline hydrocode stimulation.