Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
J Mech Behav Biomed Mater. 2020 Dec;112:104086. doi: 10.1016/j.jmbbm.2020.104086. Epub 2020 Sep 12.
The mechanical properties of soft tissues are strongly dependent on their microstructures which evolve with aging and diseases. In this paper, a micromechanical model is presented to investigate the mechanical properties of tendons and ligaments, which are treated as planar crimped fiber-reinforced composites. The interaction among the constituents in such a composite is accounted for by utilizing the Mori-Tanaka method. Explicit analytical solutions are derived for describing the effects of microstructures on its macroscopic elastic properties, which are in good agreement with both finite element analysis and relevant experimental results. It is found that fiber waviness has a significant influence on the elastic properties of tendon and ligament. Our findings also demonstrate that planar crimp is significant to achieve the large Poisson's ratio of ligament and tendon, thereby revealing a novel structure-function mechanism. Parametric analysis further elucidates that their Poisson's ratios are also dependent on the volume fractions of crimped fibers and the elastic properties of the matrix. This work not only provides a theoretical method to predict the constitutive relation of biocomposites containing wavy fibers, but also expands our knowledge on the microstructural origin of large Poisson's ratios of soft tissues.
软组织的力学性能与其微观结构密切相关，而微观结构会随着年龄的增长和疾病的发展而发生变化。本文提出了一种细观力学模型，用于研究肌腱和韧带的力学性能，将其视为平面卷曲纤维增强复合材料。利用 Mori-Tanaka 方法考虑了这种复合材料中各组成部分之间的相互作用。推导出了描述微观结构对其宏观弹性性能影响的显式解析解，这些解与有限元分析和相关实验结果吻合较好。结果表明，纤维的波纹度对肌腱和韧带的弹性性能有显著影响。我们的研究结果还表明，平面卷曲对于实现韧带和肌腱的大泊松比具有重要意义，从而揭示了一种新的结构-功能机制。参数分析进一步阐明了它们的泊松比还取决于卷曲纤维的体积分数和基体的弹性性能。这项工作不仅为预测含有波纹纤维的生物复合材料的本构关系提供了一种理论方法，而且扩展了我们对软组织大泊松比微观结构起源的认识。
