A key length scale of interest in assessing the fracture resistance of bone is the submicroscale which is composed of mineralized collagen fibrils (MCF) and extra-fibrillar matrix (EFM). Although the processes through which the submicroscale constituents of bone contribute to the fracture resistance in bone have been identified, the extent of the modifications in submicroscale mechanical response due to the changes in individual properties of MCFs and EFM has not been determined. As a result, this study aims to quantify the influence of individual MCF and EFM material property modifications on the mechanical behavior (elastic modulus, ultimate strength, and resistance to failure) of bone at the submicroscale using a novel finite element modeling approach that incorporate 3D networks of MCFs with three different orientations as well as explicit representation of EFM. The models were evaluated under tensile loading in transverse (representing MCF separation) and longitudinal (representing MCF rupture) directions. The results showed that the apparent elastic modulus at the submicroscale under both loading directions for all orientations was only affected by the change in the elastic modulus of MCFs. MCF separation and rupture strengths were mainly dependent on the ultimate strength of EFM and MCFs, respectively, with minimal influence of other material properties. The extent of damage during MCF separation increased with increasing ultimate strength of EFM and decreased with increasing fracture energy of EFM with minimal contribution from elastic modulus of MCFs. For MCF rupture, there was an almost one-to-one linear relationship between the percent change in fracture energy of MCFs and the percent change in the apparent submicroscale fracture energy. The ultimate strength and elastic modulus of MCFs had moderate to limited influence on the MCF rupture fracture energy. The results of this study quantified the extent of changes that may be seen in the energy dissipation processes during MCF rupture and separation relative to the changes in the individual constituents of the tissue. This new knowledge significantly contributes to improving the understanding of how the material property alterations at the submicroscale that can occur due to diseases, age-related changes, and treatments affect the fracture processes at larger length scales.

评估骨断裂强度的关键长度标尺是亚微米标尺，它由矿化的胶原原纤维（MCF）和原纤维外基质（EFM）组成。尽管已经确定了骨骼的亚微米级成分有助于骨骼断裂抗性的过程，但尚未确定由于MCF和EFM的各个属性的变化而导致的亚微米级机械响应改变的程度。因此，本研究旨在量化单个MCF和EFM材料性能修改对机械性能（弹性模量，极限强度，并使用新颖的有限元建模方法在亚微米级的骨骼上实现了抗破坏性和抗破坏性，该方法结合了具有三种不同方向的MCF的3D网络以及EFM的显式表示。在横向（代表MCF分离）和纵向（代表MCF破裂）的拉伸载荷下评估了模型。结果表明，在所有方向的两个加载方向上，亚微米级的表观弹性模量仅受MCFs弹性模量变化的影响。MCF的分离强度和断裂强度分别主要取决于EFM和MCF的极限强度，而对其他材料性能的影响最小。MCF分离过程中的破坏程度随EFM极限强度的增加而增加，而随EFM断裂能的增加而减小，而MCFs的弹性模量贡献最小。对于MCF破裂，MCF断裂能的变化百分比与表观亚微米级断裂能的变化百分比之间几乎是一对一的线性关系。MCF的极限强度和弹性模量对MCF破裂断裂能具有中等至有限的影响。这项研究的结果量化了MCF破裂和分离过程中能量消散过程中相对于组织各个组成部分的变化所能看到的变化程度。