Equation of State and Isentropic Releasem of Aluminum Foam and Fluoropolymer Composites

There is considerable interest in developing a better understanding of the dynamic behavior of heterogeneous materials. This study investigates and compares the dynamic response of 20 and 47% dense aluminum foam systems with and without a polytetrafluoroethylene (PTFE or Teflon) fill. Experiments on 47% foam were conduced in a 60 mm bore gun in a reverse ballistic configuration at velocities ranging from 350 m/s to 2.5 km/s. The particle velocity of the backside of the anvil was monitored with a VISAR system. Mesoscale simulations are in good agreement with the available experimental data. Both the experimental and simulated data are in good agreement with an analytic release isentrope when released from Hugoniot stress levels less than 5 GPa. However there is significant deviation from the analytic isentrope as the Hugoniot stress level is increased.