Effectiveness of meteoroid bumpers composed of two layers of distinct materials.

Abstract

Theoretical calculations describing the response of thin plate targets to hypervelocity impact are presented. The targets are composed of two layers of distinct material, and the purpose of the studies is to determine the effect of the material discontinuity on the effectiveness of the plate in breaking up the projectile and spreading the debris in the spallation bubble as it moves downrange subsequent to penetration. The thinness of the plates and the impact velocity investigated, VQ = 1.5 cm//^sec, insure that the early stages of the process are governed by a hydrodynamic model. A particle-in-cell code (VISTA) has been used to calculate the flowfield for five impact problems affording a wide variation of those factors that might be expected to influence the effectiveness of the plate as a meteoroid shield: the shock impedance ratio (poc)i/(poc)2 across the interface in the target, the initial impact pressure produced in the projectile and target at the impact surface Sp = Si, the approximate pressure transmitted through the target to its opposite free surface £2, and the mass per unit area of the target Mt. Analysis of the results of the calculations shows that of these factors, only the mass per unit area of the target is important for the geometry and velocity investigated.