This contribution presents a phenomenological viscoelastic-viscoplastic constitutive model informed by coarse-grained (CG) molecular dynamics (MD) simulations of pure glassy polystyrene (PS). In contrast to experiments, where viscoplasticity is caused by various effects simultaneously, these effects can be decomposed in MD simulations by adjusting the MD system. In the MD simulations considered here, neither bond breakage nor cross-links are introduced; instead, we focus on the intermolecular interaction of polymer chains. We employ a thermo-dynamically consistent generalized Maxwell framework parallelly comprising an elastic, a viscoelastic, and several elasto-viscoplastic modules with different yield stress to capture the viscoelastic and the viscoplastic mechanical behavior simultaneously. The yield stresses decrease with the maximum deformation the MD system has experienced. The constitutive model presented here is based on 10 material parameters, which can be identified by a few data sets and fits well the CG MD simulations of PS under uniaxial and biaxial deformation with time-proportional and cyclic loading conditions in a wide range of strain rates (0.1%/ns–20%/ns).

这一贡献提出了一种现象学的粘弹性-粘塑性本构模型，该模型以纯玻璃态聚苯乙烯（PS）的粗粒（CG）分子动力学（MD）模拟为依据。与由多种效应同时引起粘塑性的实验相反，可以通过调整MD系统在MD模拟中分解这些效应。在此处考虑的MD模拟中，既没有引入键断裂也没有引入交联。相反，我们专注于聚合物链的分子间相互作用。我们采用热力学一致的广义麦克斯韦框架，该框架并行包含具有不同屈服应力的弹性，粘弹性和几个弹粘塑性模块，以同时捕获粘弹性和粘塑性力学行为。屈服应力随着MD系统经历的最大变形而减小。本文介绍的本构模型基于10个材料参数，这些参数可以通过几个数据集进行识别，并且非常适合PS的CG MD模拟，该模拟在单轴和双轴变形下以及在时间比例和循环载荷条件下大范围的应变速率下进行（0.1％/ ns–20％/ ns）。