The elastic-plastic Richtmyer-Meshkov instability of multiple interfaces is investigated by numerical simulation using a multimaterial solid mechanics algorithm based on an Eulerian framework. This Richtmyer-Meshkov instability problem is realized by a copper layer that is flanked by vacuum and a copper block of different material strength. The research efforts are directed to reveal the influence of the layer thickness and material strength on the deformation of the perturbed solid-vacuum interface impacted by an initial shock. By varying the initial thickness ($x_{\mathrm{I}}$) of the copper layer and the yield stress (${\sigma }_{\mathrm{Y}2}$) of the copper block, two deformation modes, which have been identified as the broken mode and the stable mode, are closely scrutinized. For a fixed $x_{\mathrm{I}}$ and a decreasing ${\sigma }_{\mathrm{Y}2}$, the reflected rarefaction waves (RRWs), developing after the initial shock impacts the perturbed interface 1 (I1) between vacuum and the copper layer, become stronger after traveling across the interface 2 (I2). Subsequently, the velocity of I2 becomes larger, causing the width of I1 to grow larger. This width growth of I1 leads to a final separation of the spike from I1 and, consequently, the deformation mode changes from the stable mode to the broken mode. For a fixed ${\sigma }_{\mathrm{Y}2}$ and a decreasing $x_{\mathrm{I}}$, the RRWs impact I2 at an earlier moment with a greater strength and thus the deformation mode changes from the stable mode to the broken mode. Meanwhile, the comparison of the spike width of cases whose deformation mode is the broken mode shows that there exists a maximum value of rescaled spike width, at which the deformation mode changes from the stable mode to the broken mode.

中文翻译：

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多界面弹塑性Richtmyer-Meshkov不稳定性的数值模拟

使用基于欧拉框架的多材料固体力学算法通过数值模拟研究了多个界面的弹塑性 Richtmyer-Meshkov 不稳定性。Richtmyer-Meshkov 不稳定性问题是通过两侧为真空的铜层和不同材料强度的铜块来实现的。研究工作旨在揭示层厚度和材料强度对受初始冲击影响的扰动固-真空界面变形的影响。通过改变初始厚度（$X_{\mathrm{我}}$）的铜层和屈服应力（${\sigma }_{\mathrm{是}2}$），对铜块的两种变形模式（已确定为断裂模式和稳定模式）进行了仔细检查。对于固定的$X_{\mathrm{我}}$和不断减少的${\sigma }_{\mathrm{是}2}$，反射稀疏波 (RRW) 在初始冲击冲击真空和铜层之间的扰动界面 1 (I1) 后形成，在穿过界面 2 (I2) 后变得更强。随后，I2 的速度变大，导致 I1 的宽度变大。I1 的宽度增长导致尖峰最终与 I1 分离，因此，变形模式从稳定模式变为破坏模式。对于固定的${\sigma }_{\mathrm{是}2}$和不断减少的$X_{\mathrm{我}}$，RRW 在较早的时刻以更大的强度冲击 I2，从而使变形模式从稳定模式转变为破坏模式。同时，对变形模式为破坏模式的情况下的尖峰宽度进行比较表明，存在重新缩放的尖峰宽度的最大值，在该最大值处，变形模式从稳定模式转变为破坏模式。