Comparison of two models for the simulation of hypervelocity impacts on porous graphite

This paper presents an investigation of Hypervelocity impacts (HVI) experiments on porous graphite. Two porosity models are compared. In the first one, pore collapse is assumed to be an irreversible process during compaction, whereas the second one considers that pore collapse is mainly due to elastic, i.e. reversible, deformation. Various experimental data are analyzed and compared to simulations with both models. Three experimental data are in favor of the second model: i) volume recovering upon release after quasistatic oedometric tests; ii) crater shapes resulting from HVI experiments; iii) ejecta velocity distribution observed under HVI experiments. The detailed analysis of these results suggests that they are related to the modelling of release waves velocity, which is significantly different between both models.