柱面内爆驱动金属界面不稳定性的数值模拟研究

Simulation study of interface instability in metals driven by cylindrical implosion

对柱面爆轰驱动内壁刻有正弦扰动的金属钢壳与内部硅橡胶界面产生不稳定性问题进行数值模拟,计算结果与实验结果定性符合.与不考虑金属强度情况对比分析认为,未熔化状态下金属强度对不稳定性具有较强抑制作用,在某些加载条件下会使扰动增长率随扰动模数增加而减小.之后,对强度因素影响下内爆压缩驱动金属不稳定性问题的扰动发展规律进行了总结.在聚心反射波到达壳体之前,造成初始界面反转的RM不稳定性起主导作用,随着扰动模数增加扰动由呈近似线性发展到基本不发展变化,基本不变化后的扰动振幅也随模数增加而减小.聚心反射波作用到壳体内界面后,减速RT不稳定性作用明显增强,与强度等因素共同作用造成扰动呈明显非线性发展.无论是前期RM不稳定性主导阶段还是之后以减速RT不稳定性为主的扰动发展阶段,强度因素均能造成未熔化状态下金属不稳定性截止波长存在.

Simulation of metal instability with the initial sine perturbation on the inside of the metal shell driven by cylindrical implosion is made, and the simulation results is in accordance with the experiments. By comparing with the simulation result without considering the strength of the metals, the analysis shows that the strength of unmelted metal has a strong inhibitory effect to the metal instability, and under certain loading conditions the growth rate of the perturbation will decrease with the increase of the perturbation mode number. After that, the laws of the metal instability under explosive-driven conditions are summarized. Before the implosion reflected wave arrives at the shell, RM instability plays a dominant role. After the implosion reflected wave is applied to the shell, RT instability is significantly enhanced, the effect combined with the strength of the perturbations shows a nonlinear evolution. Under both RM and RT instability condition, the strength of metal could cause the cutoff wavelength to exist in unmelted state.