High Strain-Rate Characterization Methods for Carbon-Carbon Composites at Elevated Temperatures

Hypersonic Glide Vehicles (HGV) fly low and flat trajectories in an effort to evade current missile defense systems. Traditional interceptors are designed to have a 3-to-1 overmatch in regards to maneuverability, which may prove to be an unattainable design goal. Consequently, future interceptors will be armed with blast fragmentation warheads to increase probability of defeat. The effectiveness of the warhead will depend on the penetration resistance of the thermal protection system (TPS) on the HGV. Many TPS materials exhibit a damage mechanism known as ‘shear-plugging’ when impacted by a hypervelocity projectile. Test methods to extract strain-rate dependent strength data relevant to shear-plugging of composites do not exist. Therefore, Materials Research & Design, Inc. (MR&D) and Southwest Research Institute (SwRI) propose to develop innovative test methods for the characterization of TPS materials subjected to hypervelocity impact at elevated temperature. In this effort, SwRI will conduct split Hopkinson pressure bar (SHPB) testing on ACC-6, a well characterized carbon-carbon manufactured by C-CAT. In parallel, MR&D will develop a hydrodynamic constitutive model for 2D carbon-carbon implemented as a hydrocode user-material. Once calibrated to the SwRI data, the user-material can be used to audition specimen geometries that capture other dynamic properties relevant to shear-plugging. Approved for Public Release | 20-MDA-10398 (2 Mar 20)