Owing to the special arrangement of platelets, staggered composites can achieve superior fracture toughness. Nevertheless, a rigorous mathematical framework for the fracture analysis on them remains a challenge. Here, we show that by incorporating the mechanical behavior of individual unit cells, a multiscale analytical framework for a mode I crack propagation in staggered composites can be setup adopting the “fishnet” scheme proposed recently. The mathematical formulae for the mode I crack turn out to coincide with those for the mode III crack in homogenous ideal elastic-plastic media. Using red abalone nacre as a case study, we show that the inelastic zone in front of the crack and the R-curve given by our analysis agree remarkably well with the experiments. In the last, the design space for the damage-tolerant composites emerges from the crack sensitivity analysis, which could guide the advanced materials design.

由于血小板的特殊排列，交错的复合材料可以获得出色的断裂韧性。然而，对它们进行断裂分析的严格数学框架仍然是一个挑战。在这里，我们表明，通过结合单个晶胞的机械行为，可以采用最近提出的“鱼网”方案来建立交错结构中I型裂纹扩展的多尺度分析框架。在均匀的理想弹塑性介质中，I型裂纹的数学公式与III型裂纹的数学公式一致。以红色鲍鱼珍珠质为例，我们显示了裂纹前面的无弹性区域和R我们的分析给出的曲线与实验非常吻合。最后，通过裂纹敏感性分析得出了耐损伤复合材料的设计空间，可以指导先进的材料设计。