Sutures, the soft collagenous tissue joining interdigitating bony protrusions on the edges of bone plates, play a significant mechanical role in allowing a turtle shell to respond optimally to a range of loading regimes. In this contribution, qualitative and quantitative aspects of the mechanical behaviour of turtle shell suture regions are investigated by means of mathematical modelling. Notable features of the model include: (i) a geometrically realistic three dimensional model for the suture geometry; (ii) taking the hyperelastic, anisotropic and incompressible nature of the suture material into account; and (iii) a novel method for defining the collagen fibre directions within the suture. The model is validated against a physical three point bending test and replicates many of the qualitative and quantitative aspects of the mechanical behaviour. The model is then used to elucidate the effect that sutures have on the shell’s mechanical behaviour during a predator attack. It is found that the sutures increase the energy required from a predator during an attack whilst cushioning the brittle bone, and so protecting it from fracture. Additionally, longer bony protrusions increase strain energy absorption but also increase the likelihood of fracture.

缝线是一种柔软的胶原蛋白组织，与骨板边缘上的相互交叉的骨突起相连，在使龟壳对各种加载方式产生最佳响应方面起着重要的机械作用。在这一贡献中，通过数学建模的方法研究了龟壳缝合区域的力学行为的定性和定量方面。该模型的显着特征包括：（i）缝线几何形状的几何逼真的三维模型；（ii）考虑到缝合材料的超弹性，各向异性和不可压缩性；（iii）定义缝合线内胶原纤维方向的新颖方法。该模型针对物理三点弯曲测试进行了验证，并复制了机械行为的许多定性和定量方面。然后，使用该模型阐明缝线在掠食者攻击期间对壳的机械行为的影响。已经发现，缝线在发作期间增加了捕食者所需的能量，同时缓冲了脆性骨，从而保护了其免于断裂。此外，较长的骨质突起可增加应变能吸收，但也会增加骨折的可能性。