Effect of phase change in a debris cloud on a backwall structure

Abstract

The physical state of a debris cloud generated upon impact of a thin flier plate with a thin bumper depends on the impact velocity. At impact velocities of 10 km/s, the debris cloud is expected to be primarily molten with some vapor present. A series of calculations using the finite‐difference code CTH has been used to evaluate the effect of phase change (i.e., higher concentrations of vapor) in debris clouds and their subsequent impact on a backwall structure. In these calculations, the higher concentrations of vapor is achieved by increasing the initial temperature of the impactor and the bumper material while keeping the same impact velocity. The nature of the interaction of the debris cloud and the subsequent loading on the backwall depends on its thermophysical state. This interaction (with a backwall) can cause either spallation, rupture, or simply bulging of the backwall structure. These results will be discussed and compared with an impact experiment performed at ≊10 km/s on the Sandia hypervelocity launcher. In the experiment, the debris cloud was generated by the impact of a titanium plate with a titanium bumper.