We have studied spallation in impact-loaded copper and mild steel plates, using one- and two-dimensional hydrodynamic simulations. Two damage models have been used to determine the evolution of void volume, taking into account the effect of damage on material strength and the equation of state. Our results agree reasonably well with experimental observations described in a Russian spall database. The Void Growth model surprisingly yields a closer match with experiment, even though the Nucleation and Growth model includes more detailed physical effects. The effect of impact pressure and tensile wave duration on spall parameters has been studied. For both kinds of targets, the computed spall thickness decreases monotonically with increase in flyer velocity, which is in accord with experimental observations in aluminum targets. For both copper and MS, the spall strength is found to generally increase monotonically with impact pressure, a feature reported in experiments with aluminum targets. However, for both materials, the computed increase is preceded by an initial drop, which we cannot yet explain. For a copper target, the spall strength increases by at most 20% as its initial temperature increases from room temperature to ～80% of the melting point. This matches experimental trends.
展开▼
