In Situ Optical Investigations of Hypervelocity Impact Induced Dynamic Fracture

One of the prominent threats in the endeavor to develop next-generation space assets is the risk of space debris impact in earth’s orbit and micrometeoroid impact damage in deep space. To date, there is no study available which concentrates on the analysis of dynamic crack growth from hypervelocity impacts on such structures, resulting in their eventual catastrophic degradation. Experiments conducted using a unique two-stage light-gas gun facility have examined the in situ dynamic fracture of brittle polymers subjected to this high-energy-density event. Optical techniques of caustics and photoelasticity, combined with high-speed photography, analyze crack growth behavior of Mylar and Homalite 100 thin plates after impact at velocities ranging from 3 to 7 km/s (7,000–15,500 mph). Results indicate that even under extreme impact conditions of out-of-plane loading, highly localized heating, and energetic impact phenomena involving plasma formation and ejecta, the dynamic fracture process occurs during a deformation regime dominated by in-plane loading.