A few questions on the spallation behavior resolved by the measurement of free-surface velocity profile have been discussed. Firstly, the way from the measured free-surface velocity profile to infer the dynamic damage behavior of the target is an “Inverse Problem” and the theoretical model and simulation parameters determined by such a solution maybe not represent the real physical nature of spall fracture inside the target. Secondly, how to calculate the spall strength? Due to the attenuation effect of micro-voids or damage on the wave propagation, the spall strength computed from the free-surface velocity profile is apparently lower than the tensile strength suffered by the shocked material. Thirdly, limitation of the traditional single-point measurement on the free-surface velocity profile is briefly reviewed. Given that the shocked target is inhomogeneous, the amplitude of the measured velocity profile is varied from point to point. According to these discussions, future research suggestions have been proposed in order to clearly understand the spallation behavior.

spall  /  damage  /  free-surface velocity profile