Internal collision jetting mechanism of cellular foams under dynamic compression in high-to-hypervelocity regime

The compressive process and internal collision behavior of cellular foams under dynamic uniaxial compression in high-to-hypervelocity regime are studied based on the 2D Voronoi mesoscale model. The critical angle for internal collision-induced jetting and jetting velocities are analyzed theoretically and numerically based on the distribution of the ligament orientation in the mesoscale structure. It is shown that the 1D shock model based on conservation laws is generally valid across a wide range of compression velocities, involving both compaction shock and collision-induced jetting mechanisms. By statistically calculating the average collision force of an equivalent single particle, the characteristics of the internal collision is evaluated for cellular foams with different pore sizes. In addition, the dynamic uniaxial compression stress is determined by Hugoniot relationship in a wide range of impact velocities. This study provides a physical explanation for the numerical and experimental observations of the internal collision, compaction and jetting phenomena in cellular foam under 1D high-to-hypervelocity impact.