Computational studies can supplement existing ultrahigh strain rate experimental techniques in the absence of invasive full-field measurement and visualization. In this study, a computational model is employed to elucidate various phenomena accompanying the generation, propagation, and interaction of multimode shock waves in a viscoelastic material. Specifically, a 4 mm diameter polyurea plug with a thickness of 0.5 mm was modeled as a linear viscoelastic solid, where the relaxation behavior of the shear modulus was described using a Prony series while the bulk modulus was assumed to be linear elastic based on the Poisson's ratio of polyurea. The results are presented in three case studies, where a different type of shock wave was emphasized in each case while focusing on the regions at the leading and trailing edges of the shock wavefront. Generally, the wavefront interacted with the accompanying and reflected waves, resulting in compromising the purity of the sought-after loading condition, especially during the return trip of the wave upon approaching the free surface. In Case Study I, the propagation of laser-induced pressure wave remained pure during the forward trip towards the free surface but was compromised by the accompanying shear wave and side spherical patterned pressure waves. Case Study II simulated the generation of surface waves by incorporating a ring-shaped loading site, where the release of a surface displacement was found to be focused and amplified at the central point. In the final case study, Case Study III, the applied shear wave at ultrahigh strain rate generated secondary pressure and horizontal shear waves at the edges of the loading site, which complicated the loading scenario but provided new insight into the interaction of laser-generated shock waves within the solid. The results can be used to improve the analysis of experimental data to quantify the accompanying deformation and failure mechanisms of polymers subjected to hypervelocity impacts.

在没有侵入性全场测量和可视化的情况下，计算研究可以补充现有的超高应变率实验技术。在这项研究中，一个计算模型被用来阐明伴随着粘弹性材料中多模冲击波的产生、传播和相互作用的各种现象。具体而言，直径为 4 mm、厚度为 0.5 mm 的聚脲塞被建模为线性粘弹性固体，其中剪切模量的松弛行为使用 Prony 系列描述，而体积模量假定为基于泊松方程的线弹性聚脲的比例。结果呈现在三个案例研究中，在每个案例中都强调了不同类型的冲击波，同时关注冲击波前缘的前缘和后缘区域。通常，波前与伴随波和反射波相互作用，从而损害了所追求的载荷条件的纯度，尤其是在波接近自由表面时的回程期间。在案例研究 I 中，激光诱导压力波的传播在朝向自由表面的前向旅行期间保持纯净，但受到伴随的剪切波和侧球面图案压力波的影响。案例研究 II 通过结合环形加载点模拟了表面波的产生，发现表面位移的释放集中在中心点并放大。在最后一个案例研究案例研究 III 中，超高应变率下施加的剪切波在加载地点的边缘产生了二次压力和水平剪切波，这使加载场景复杂化，但为固体内激光产生的冲击波的相互作用提供了新的见解。结果可用于改进对实验数据的分析，以量化受到超高速冲击的聚合物的伴随变形和破坏机制。