骨齿对龟甲骨质层中骨缝结构强度和韧性的影响

Influence of bone teeth on strength and toughness of sutured bone plate of turtle shell

龟壳背甲的骨质板由多根独立的肋骨组成,内部的骨缝结构将独立的肋骨组成整体骨质板.基于单轴拉伸、弯曲实验和有限元分析,本文研究了骨缝结构中的骨齿对龟甲骨质板整体强度和韧性的影响.微观形貌观测实验实验表明,龟甲骨质板骨缝结构中的骨齿带有三棱锥和四棱锥的凹槽构型,与已有研究中假设的完美圆锥型结构有着显著差异.通过3D打印技术制备了带有三棱锥和四棱锥凹槽构型的骨缝结构仿生试件并进行了力学测试.结果表明,骨齿的齿峰-齿谷比值是影响骨缝结构整体强韧性的关键因素,而非假设的骨齿侧表面积和投影面积.对于给定形状的骨齿结构而言,齿峰-齿谷比值越大则骨质板的强度和韧性则越大.对龟壳背甲带骨缝的骨质板和相应的仿生试件进行了三点弯曲实验测试,结果同样表明骨齿的齿峰-齿谷比值是整体强韧性能的决定性参数.本文的结果对于缝结构材料的强韧化仿生设计具有指导意义.

The bone plate of turtle shell carapace is formed by several individual ribs through the suture structure of bone teeth.Based on the tensile and bending experiments as well as finite element analysis,the influence of bone teeth at the suture on the strength and toughness of the bone plate of turtle shell carapace is studied in this paper.Precisely morphological characterization shows that the bone teeth at the suture of bone plate are mainly formed by triangle and quadrilateral grooved cones instead of the perfect cone that is often assumed.Similar to the bone plate,3D printed samples with suture structures formed by triangle or quadrilateral grooved conical teeth are then prepared.Based on the natural and printed samples,the tensile tests combined with the finite element calculations find that the peak-to-valley ratio of bone teeth is a key factor that can explain the strength and toughness of the sutured bone plate varying with the shape of bone teeth,instead of the supposedly lateral surface area or the project area of bone teeth.For bone teeth with a given shape,the larger the peak-to-valley ratio,the larger the strength and toughness of the bone plate are.Comparison of the bending experimental result of 3D printed suture structures with grooved conical bone teeth and that of the natural sutured bone plate of turtle shell carapace further verifies the finding that the peak-to-valley ratio is a decisive parameter on the strength and toughness of suture structure of bone teeth.The results of this paper should be of significance to the biomimetic design of suture structures with high strength and toughness.