Dynamic cratering of graphite: Experimental results and simulations

摘要: The cratering process in brittle materials under hypervelocity impact (HVI) is of major relevance for debris shielding spacecraft or high-power laser applications. Amongst other materials, carbon particular interest since it widely used as elementary component composite materials. In this paper we study a porous polycrystalline graphite HVI and impact, both leading to strong ejection cratering. First, report new experimental data normal impacts at 4100 4200 m s-1 500-μm-diameter steel sphere on thick sample graphite. second step, dynamic loadings have been performed with nanosecond facility. High-resolution X-ray tomographies observations scanning electron microscope order visualize the crater shape subsurface cracks. These two post-mortem diagnostics also provide evidence that, case tests, fragmented was buried into target below surface. current aims propose an interpretation results, including projectile trapping. spite their efficiency capture overall trends size shape, semi-empirical scaling laws do not usually predict these phenomena. Hence, offer better insight processes observation, need computational damage model argued. After discussing energy partitioning identify dominant physical mechanisms occurring our experiments, simple Compaction fracture phenomena are included model. A failure criterion relying Weibull theory relate material tensile strength deformation rate damage. constitutive relations implemented Eulerian hydrocode compute numerical simulations confront them experiments. paper, fitting procedure unknown parameters based results. Good agreement found shapes dimensions, well velocity. inclusion reproduced by mechanism proposed trapping process. At least sets can be match Finally, show that experiment may discriminate favor one set parameters.