针对金属材料卸载过程中计算结果与实验数据之间存在比较大差异的现象,在卸载段采用与加载段不同的剪切模量,描述金属材料动态响应过程中卸载初期的准弹性卸载过程,结合所选取的本构模型和损伤演化模型,对靶材料冲击加载过程中的卸载、损伤、层裂等过程进行理论和数值模拟研究,数值模拟结果表明,文中采取的模型,对于动态响应过程中准弹性卸载过程、后续的损伤以及完全层裂过程的描述比较合理,获得了与实验数据符合比较好的计算结果。

The unloading characteristics are studied to explain the difference between the simulation results and the experimental data in this paper. The different elastic-plastic limiting conditions between the loading and the unloading processes are used to describe the quasi-elastic unloading of the earlier unloading. The critical damage model and the Steinberg-Guinan constitutive model are used to simulate the shock-unloading spallation process and the second loading process of Fe and Al. The simulation results indicate that the method used in this paper can describe quasi-elastic phenomena reasonably well. The results of the damage evolution and the spallation compare favorably with the experiment data at the complete spallation. But in the case of Al experiment, the incomplete spallation occurs because of the lower shock velocity, and it can not be described well with the macroscopic damage evolution model, which explains the difference between the simulation results and the experimental data.