A strain-rate-sensitive polyurethane elastomer is numerically investigated to reveal improved impact characteristics and analyze the concerned rate dependencies and dynamic energy dissipation features. A physical constitutive model in view of amorphous molecular structure of the elastomer is proposed by relating the macro-mechanical behaviors to micro-structural changes through molecular transitions and flow activations. Two distinct relaxation processes are considered because of entangled molecular networks, with each possessing a unique activation energy. Through calibration with experimental data, finite element simulations based on the model are conducted. Related to the loading rate, the structural entropy of molecular chain entanglements, rate-dependent yielding, plateau flow and densification are well predicted by the model. The investigations are extended further regarding the material recoverability and accordingly, strain energy absorptions are illustrated. A power law function is proposed for designing the energy absorption relation to the applied loading rate. Finally, the inherent mechanisms causing the dynamic energy absorptions are analyzed with notable clarifications of post-experimental observations obtained via scanning electron microscopy.

对应变速率敏感的聚氨酯弹性体进行了数值研究，以揭示改进的冲击特性并分析相关的速率依赖性和动态能量耗散特征。通过将宏观力学行为与通过分子转变和流动激活的微观结构变化联系起来，提出了一种考虑到弹性体的无定形分子结构的物理本构模型。由于纠缠的分子网络，我们考虑了两种不同的弛豫过程，每个过程都具有独特的活化能。通过实验数据标定，基于该模型进行有限元仿真。与加载速率相关，该模型可以很好地预测分子链缠结的结构熵、速率相关屈服、平台流动和致密化。关于材料可恢复性的研究进一步扩展，并因此说明了应变能量吸收。提出了幂律函数来设计能量吸收与应用加载率的关系。最后，通过扫描电子显微镜获得的实验后观察的显着澄清，分析了导致动态能量吸收的内在机制。