Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai Institute of Applied Mathematics and Mechanics, School of Mechanics and Engineering Science, Shanghai University, Shanghai, 200444, China.
Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai Institute of Applied Mathematics and Mechanics, School of Mechanics and Engineering Science, Shanghai University, Shanghai, 200444, China; Shaoxing Institute of Technology, Shanghai University, Shaoxing, 312074, China.
J Mech Behav Biomed Mater. 2023 May;141:105761. doi: 10.1016/j.jmbbm.2023.105761. Epub 2023 Mar 7.
Mineralized collagen fibril (MCF) arrays are important structural elements involved in inelastic deformation and fracture process of bone. Recent experiments have shown that MCF breakage has an influence on toughening of bone. Motivated by the experiments, we carry out the analyses of fracture in staggered MCF arrays. The plastic deformation of extrafibrillar matrix (EFM), debonding of the MCF-EFM interface, plastic deformation of MCFs and MCF fracture are accounted for in the calculations. It is found that the fracture of MCF arrays is controlled by competition between MCF breakage and debonding of the MCF-EFM interface. The MCF-EFM interface with high shear strength and large shear fracture energy is capable of activating MCF breakage, which promotes plastic energy dissipation of MCF arrays. In the absence of MCF breakage, damage energy dissipation is higher than plastic energy dissipation and debonding of the MCF-EFM interface provides the major contribution to toughening of bone. We have further revealed that the relative contributions of interfacial debonding mechanism and plastic deformation of MCF arrays are dependent on fracture properties of the MCF-EFM interface in the normal direction. The high normal strength gives rise to enhanced damage energy dissipation and amplified plastic deformation of MCF arrays; while high normal fracture energy of the interface suppresses plastic deformation of MCFs.
矿化胶原纤维束（MCF）阵列是参与骨骼非弹性变形和断裂过程的重要结构元素。最近的实验表明，MCF 的断裂对骨骼的增韧有影响。受实验的启发，我们对交错 MCF 阵列中的断裂进行了分析。在计算中考虑了纤维外基质（EFM）的塑性变形、MCF-EFM 界面的脱粘、MCF 的塑性变形和 MCF 断裂。结果发现，MCF 阵列的断裂受 MCF 断裂和 MCF-EFM 界面脱粘之间竞争的控制。具有高剪切强度和大剪切断裂能的 MCF-EFM 界面能够激活 MCF 断裂，从而促进 MCF 阵列的塑性能量耗散。在没有 MCF 断裂的情况下，损伤能量耗散高于塑性能量耗散，而 MCF-EFM 界面的脱粘提供了骨骼增韧的主要贡献。我们进一步揭示了界面脱粘机制和 MCF 阵列的塑性变形的相对贡献取决于 MCF-EFM 界面在法向上的断裂性能。法向强度的增加导致损伤能量耗散的增强和 MCF 阵列的塑性变形的放大；而界面的高法向断裂能抑制了 MCF 的塑性变形。
