The Bouligand structure, prominent in arthropod cuticles and fish scales, is a fibrous laminate where the orientation of the fibers increases incrementally across the thickness. Complex three-dimensional fracture mechanisms (crack twisting) have recently been intriguing researchers as a potential source of toughness. Capturing the interaction of propagating cracks with this complex architecture, however, remains a challenge and usually requires computationally expensive models. We ask the question: Given identical fibers and interfaces, is the Bouligand architecture tougher than other types of cross-plies? Here we use the discrete element method (DEM) to capture the main fracture mechanisms in fibrous laminates: crack deflection, crack twisting, delamination, process zone and fiber fracture, and to capture how various contrasts of properties between fibers and matrix affect these mechanisms. Our main conclusion is that in terms of fracture toughness (initiation and propagation), the Bouligand is outperformed by the (0${}^{\circ }$/90°) cross-ply for any crack orientation. The Bouligand structure is however more isotropic in-plane in terms of both stiffness and toughness, which may confer some advantage for multiaxial loading and could explain why this architecture is often found in nature.

Bouligand结构在节肢动物表皮和鱼鳞中很显眼，是一种纤维层压板，其中纤维的取向沿厚度方向逐渐增加。复杂的三维断裂机制（裂纹扭曲）最近吸引了研究人员作为韧性的潜在来源。但是，如何利用这种复杂的体系结构捕获传播裂纹的相互作用仍然是一个挑战，并且通常需要计算量大的模型。我们问一个问题：如果有相同的光纤和接口，那么Bouligand体系结构是否比其他类型的交叉网架更坚韧？在这里，我们使用离散元方法（DEM）来捕获纤维层压板的主要断裂机理：裂纹偏转，裂纹扭曲，分层，工艺区域和纤维断裂，并捕获纤维和基质之间的各种对比如何影响这些机理。我们的主要结论是，就断裂韧性（起始和扩展）而言，Bouligand的性能优于（0${}^{\circ }$/ 90°）交叉铺展，以适应任何裂缝方向。但是，就刚度和韧性而言，Bouligand结构在平面内更具各向同性，这可能会给多轴载荷带来一些优势，并可以解释为什么这种结构经常在自然界发现。