Particulate Impact/Erosion Phenomena and Materials Failure for Supersonic KVs

A first generation erosion model for silicon nitride radome materials will be developed to determine the fracture and material ejecta characteristics as a function of flight conditions experienced by the kill vehicle. Silicon nitride samples will experience tightly controlled liquid impact and nylon bead impact using the Marshall Space Flight Center’s Hydrometeor Test Facility over a range of impact angles and velocities. The experimental data will be correlated directly to the theoretical model for validation of the model assumptions and algorithms. The model will consider the effect of drop distortion, variable loading times of the drop upon the substrate surface, and the effects of multiple drops leading to fracture coalescence throughout the substrate. The model will be able to map the rate of fracture growth, depth of penetration, material ejecta, instantaneous and transient loads, as well as strength reduction of the silicon nitride. This modeling capability will be integrated into the ATAC3D code as a stand-alone or complimentary software module. This model will provide the capability to assess the material’s mechanical degradation as a function of time and environmental exposure.