Yamaguchi Tetsuo, Onoue Yudai, Sawae Yoshinori
Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan.
International Institute for Carbon-Neutral Energy Research, Kyushu University, Fukuoka 819-0395, Japan.
Phys Rev Lett. 2020 Feb 14;124(6):068002. doi: 10.1103/PhysRevLett.124.068002.
The toughening of sparse elastic networks, such as hydrogels, foams, or meshes against fracture is one of the most important problems in materials science. However, the principles of toughening have not yet been established despite urgent engineering requirements and several efforts made by materials scientists. Here we address the above-mentioned problem by focusing on the topology of a network. We perform fracture experiments for two-dimensional periodic lattices fabricated from rubber strings and connecters with well-defined topological structures. We find that systematic increase in the largest coordination number while maintaining the average coordination number (=4) as constant leads to significant improvement in toughness. We reproduce the observed toughening behavior through numerical simulations and confirm that the stress concentration in the vicinity of a crack tip can be controlled by the topology of the network. This provides a new strategy for creating tough sparse elastic networks, especially hydrogels.
诸如水凝胶、泡沫或网眼等稀疏弹性网络的增韧以防止断裂是材料科学中最重要的问题之一。然而，尽管有迫切的工程需求以及材料科学家们做出的多项努力，增韧原理尚未确立。在此，我们通过关注网络的拓扑结构来解决上述问题。我们对由具有明确拓扑结构的橡胶绳和连接件制成的二维周期性晶格进行了断裂实验。我们发现，在保持平均配位数（=4）不变的情况下，最大配位数的系统性增加会导致韧性显著提高。我们通过数值模拟再现了观察到的增韧行为，并证实裂纹尖端附近的应力集中可以通过网络的拓扑结构来控制。这为创建坚韧的稀疏弹性网络，尤其是水凝胶，提供了一种新策略。
