Biological structures integrate morphometry (shape-based rules) with materials design to maximize organism survival. The exoskeleton of the armored fish, Polypterus senegalus, balances flexibility with protection from predatory and territorial threats. Material properties of the exoskeleton are known; however, the geometric design rules underlying its anisotropic flexibility are uncharacterized. Here, we show how scale shape, articulation, and composite architecture produce anisotropic mechanics using bio-inspired, multi-material 3D-printed prototypes. Passive loading (draping) shows that compliant connections between the scales contribute to mechanical anisotropy. Simulated and experimental active loading (bending) show orientation-dependent stiffness ranging over orders of magnitude, including ‘mechanical invisibility’ of the scales where they do not add stiffness to the exoskeleton. The results illustrate how morphometry provides a powerful tool to tune flexibility in composite architectures independent of varying constituent materials composition. We anticipate that introducing morphometric design strategies will enable flexible, protective systems tuned to complex shapes and functions.

生物结构将形态学（基于形状的规则）与材料设计结合在一起，以最大化生物的生存。装甲鱼塞内加卢斯的外骨骼在保护灵活性与抵御掠夺性和领土性威胁之间取得平衡。外骨骼的材料特性是已知的。但是，其各向异性柔性所基于的几何设计规则尚未得到体现。在这里，我们展示了鳞片的形状，铰接和复合结构如何使用受生物启发的多材料3D打印原型产生各向异性力学。被动载荷（悬垂性）表明，秤之间的顺应性连接会导致机械各向异性。模拟和实验性主动载荷（弯曲）显示了与方向相关的刚度，范围超过了几个数量级，包括标尺的“机械隐形”，其中标尺没有为外骨骼增加刚度。结果说明了形态计量学如何提供一个功能强大的工具来调整复合结构中的灵活性，而与组成材料的成分变化无关。我们预计，引入形态计量学设计策略将使灵活的保护系统能够适应复杂的形状和功能。