A COMPUTATIONAL STUDY OF PROJECTILE MELT IN IMPACT WITH TYPICAL WHIPPLE SHIELDS

This paper presents scaling results based on simulations with the CALE hydrodynamics code [1] of aluminum projectile impacts on typical alum inum Whipple shields at speeds of 6 to 14 km/s. The objective was to d etermine the extent of projectile and target material melting. The app roach was to perform a matrix of computer simulations varying the impa ct speed from 6 to 14 km/s and varying the areal density of the shield from 5 percent to 80 percent of the centerline areal density of the p rojectile. The projectile radius was fixed at 9.5 mm (mass = 1.27 gram s). The melt state of the projectile material and the shield material was assessed after release of the initial shock. The postrelease speci fic energy in the projectile and in the shield was compared with the e nthalpy of incipient melt and the enthalpy of complete melt provided i n the Hultgren Tables [2]. Material with specific energy greater than the enthalpy of complete melt was assumed to be fully melted; material with specific energy greater than the enthalpy of incipient melt but less than that of complete melt was assumed to be partially solid and partially melted mixed phase material with no strength; and material w ith specific energy less than the enthalpy of incipient melt was assum ed to be in a solid state with strength. It is likely that this solid material is in a highly fragmented state as a result of the initial sh ock.