标题： 关于软聚合物断裂的建模 显示英文标题

标题： On modeling fracture of soft polymers

摘要： 软聚合物是自然界和工程材料中常见的材料，其性能从与速率无关到显著依赖速率，这取决于交联机制。 当前的断裂韧性测量方法，如能量释放率，对于速率依赖性软材料来说，在不同的加载轮廓和试样几何形状下是非唯一的。 关于在速率依赖性软聚合物中建模断裂的研究仅限于特定预裂纹几何形状的裂纹尖端应力场分析或裂纹尖端驱动力方法。 我们开发了一个模型，基于广义的多机制梯度损伤框架来预测软聚合物中的损伤起始和扩展。 我们提出并证明了应力功的一个临界值$\mathit{W}_{cr}$可以唯一量化在一种加载模式下材料点完全失效相关的单位参考体积总能量耗散。 $\mathit{W}_{cr}$可以通过均匀变形实验进行评估，而无需本构模型。 $\mathit{W}_{cr}$被证明对于两种速率依赖性软聚合物以及弹性体的不同加载模式下近似恒定。 我们提出了对$\mathit{W}_{cr}$的能量贡献作为合适的损伤起始准则。 损伤模型中的所提出的起始准则成功地预测了在多种实验中重要速率刚化软聚合物聚硼硅氧烷的断裂，这些实验涉及不同的试样几何形状和加载条件。 该模型还为聚硼硅氧烷相关的微结构过程提供了一致的能量密度估计。 该断裂模型的更广泛应用通过其能够预测弹性体（EPDM）和另一种粘性软聚合物（EPS25 热固性树脂）的断裂得到展示。 显示英文摘要

摘要： Soft polymers are ubiquitous materials found in nature and as engineering materials with properties varying from rate-independent to significantly rate-dependent depending on the crosslinking mechanisms. Current fracture toughness measures such as energy release rate are non-unique for rate-dependent soft materials for varying loading profiles and specimen geometries. Works on modeling fracture in rate-dependent soft polymers are limited to crack tip stress field analyses or crack tip driving force approaches for specific pre-cracked geometries. We have developed a model to predict damage initiation and growth in soft polymers based on a generalized multi-mechanism gradient damage framework. We propose and show that a critical value of stress work $\mathit{W}_{cr}$ can uniquely quantify the total energy dissipation per unit referential volume associated with the complete failure of a material point under a loading mode. $\mathit{W}_{cr}$ can be evaluated using homogeneous deformation experiments and without a constitutive model. $\mathit{W}_{cr}$ is demonstrated to be approximately constant with strain rate for two rate-dependent soft polymers and different loading modes for an elastomer. We propose the energetic contribution to $\mathit{W}_{cr}$ as a suitable damage initiation criterion. The proposed initiation criterion in the damage model enabled successful predictions of fracture in an important rate-stiffening soft polymer Polyborosiloxane in a variety of experiments involving different specimen geometries and loading conditions. The model also provides a consistent energy density estimate for fracture-associated microstructural processes in Polyborosiloxane. The broader applicability of the fracture model is shown by its ability to predict fracture in an elastomer (EPDM) and another viscous soft polymer (EPS25 vitrimer).