Ji H M, Qi Q J, Liang S M, Yu H, Li X W
Department of Materials Physics and Chemistry, School of Material Science and Engineering, and Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819, China.
School of Materials and Chemical Engineering, Pingxiang University, Pingxiang, 337055, China.
Acta Biomater. 2022 Sep 15;150:310-323. doi: 10.1016/j.actbio.2022.07.031. Epub 2022 Jul 28.
Tubercles in sea urchin shells serve as a base on the test plates connecting the spine; these undergo compressive or impact stress from the spines. As the volume fraction of the ordered stereom structure in a tubercle increases, the compressive load-displacement curves are gradually characterized by the typical behavior of ceramic foams. Although this ordered stereom structure only exhibits an average porosity of 50.6%, it also exhibits high fracture resistance and energy dissipation capacity. Such remarkable behavior of the ordered stereom structure is attributed to its unique hierarchical microstructure. Specifically, at the macroscale, the stereom structure is periodic. It has uniformly distributed pores that are typically round, which can effectively reduce the stress concentration around the pores, and the ordered arrangement of the trabeculae along the axial direction of the tubercle bears the most compressive stress. The trabeculae present a bottleneck shape with a specific dimension, ensuring the best fracture resistance with a relatively higher porosity. Furthermore, crack deflection in the trabeculae changes the local fracture mode of the mineral, thereby increasing the crack surface area. STATEMENT OF SIGNIFICANCE: The connecting bases of the spines in sea urchin shell, known as tubercle, effectively undergo the compressive stress or impact stress from the spines. An ordered stereom structure is found in the tubercle, and it shows an excellent fracture resistance and energy dissipation capacity. Such a fantastic behavior of the ordered stereom structure mainly takes advantage of its unique hierarchical microstructure. The stereom structure presents a periodic structure on macroscale, the trabeculae show a bottleneck shape with a specific dimension to guarantee the best fracture resistance with a relatively higher porosity, and the soft fillers among CaCO nanoparticles in a trabecula cause consecutive crack deflections.
海胆壳上的瘤状物作为连接棘刺的测试板的基部；这些部位会承受来自棘刺的压缩或冲击应力。随着瘤状物中有序立体结构的体积分数增加，压缩载荷 - 位移曲线逐渐呈现出陶瓷泡沫的典型特征。尽管这种有序立体结构的平均孔隙率仅为50.6%，但它也具有高抗断裂性和能量耗散能力。有序立体结构的这种显著特性归因于其独特的分级微观结构。具体而言，在宏观尺度上，立体结构是周期性的。它具有均匀分布的通常为圆形的孔隙，这可以有效降低孔隙周围的应力集中，并且沿瘤状物轴向排列的小梁有序排列承受了大部分压缩应力。小梁呈现出具有特定尺寸的瓶颈形状，以相对较高的孔隙率确保最佳的抗断裂性。此外，小梁中的裂纹偏转改变了矿物的局部断裂模式，从而增加了裂纹表面积。重要性声明：海胆壳中棘刺的连接基部，即瘤状物，有效地承受了来自棘刺的压缩应力或冲击应力。在瘤状物中发现了一种有序立体结构，它表现出优异的抗断裂性和能量耗散能力。有序立体结构的这种奇妙特性主要得益于其独特的分级微观结构。立体结构在宏观尺度上呈现出周期性结构，小梁呈现出具有特定尺寸的瓶颈形状以保证在相对较高孔隙率下的最佳抗断裂性，并且小梁中碳酸钙纳米颗粒之间的软填料会导致连续的裂纹偏转。
