To pre-compress the disk-shaped LY12 samples along the radial direction can be done with the aid of overstress assembly by heating or by mechanical clamping,which can also generate the deviatoric stress fields under different states.The spallation signals of these pre-compressed samples are measured by VISAR in the light-gas gun shock experiments.The experimental results show that even under the same impact velocity,the pullback amplitudes of the velocity at the free surface of the samples vary significantly.According to the experimental data,we propose a distinct concept that the material spallation strength is closely related to the deviatoric stress fields in the material.Based on the numerical simulation,we develop a damage constitutive model,which reveals that the deviatoric stress reduces the tensile threshold of the void growth.The numerical investigations also demonstrate that the spallation strength decreases as pre-compression increases.The experimental idea proposed in this paper can also be used to study the spallation process in other structures.
ShiWen ZhangCangLi LiuQingZhong LiJinSong HuaQiao Liu
