The double network hydrogels (DN gels) process high fracture toughness due to their considerable energy dissipation during fracture. To effectively interpret the energy dissipation, it is imperative to conduct a study on the quantitative characterization of the dissipated energy density distribution and the damage zone around the crack tip. In this study, we propose a series of tearing tests on pre-stretched DN gel specimens to quantitatively characterize the dissipated energy density distribution. According to the dissipated energy density distribution, the damage zone of the DN gel during tearing is divided into three parts: hardening zone, yielding zone and pre-yielding zone. The dissipated energy density distribution determines both the feature size and the contribution of these damage zones to the fracture toughness. We reveal that both the dissipated energy density and the feature size of the damage zones significantly influence the fracture toughness. Additionally, this study delves into the effect of the first network's cross-linking degree on the dissipated energy density distribution and damage zone. The dissipated energy density distribution, determined by tearing test, is validated by available experimental results, which show good agreement. This study proposes a quantitatively experimental method to investigate the dissipated energy density distribution and damage zone. It is anticipated that this approach will provide new insights into the energy dissipation mechanism of soft materials.

中文翻译：

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表征双网络水凝胶中的耗散能量密度分布和损伤区


双网络水凝胶 （DN 凝胶） 由于在断裂过程中具有相当大的能量耗散，因此具有很高的断裂韧性。为了有效地解释能量耗散，必须对耗散能量密度分布和裂纹尖端周围的损伤区进行定量表征研究。在这项研究中，我们提出了对预拉伸 DN 凝胶样品的一系列撕裂测试，以定量表征耗散能量密度分布。根据耗散能量密度分布，DN凝胶在撕裂过程中的损伤区分为硬化区、屈服区和预屈服区三部分。耗散能量密度分布决定了特征大小和这些损伤区对断裂韧性的贡献。我们揭示了耗散能量密度和损伤区的特征大小都显着影响断裂韧性。此外，本研究深入探讨了第一网络的交联度对耗散能量密度分布和损伤区的影响。通过撕裂试验确定的耗散能量密度分布由现有的实验结果验证，这些结果显示出良好的一致性。本研究提出了一种定量实验方法来研究耗散能量密度分布和损伤区。预计这种方法将为软材料的能量耗散机制提供新的见解。