A comprehensive understanding of biological tissue mechanics is crucial for designing engineered tissues that aim to recapitulate native tissue behavior. Tensile mechanics of many fiber-reinforced tissues have been shown to depend on specimen geometry, which makes it challenging to compare data between studies. In this study, a validated multiscale, structure-based finite element model was used to evaluate the effect of specimen geometry on multiscale annulus fibrosus tensile mechanics through a fiber engagement analysis. The relationships between specimen geometry and modulus, Poisson's ratio, tissue stress–strain distributions, and fiber reorientation behaviors were investigated at both tissue and sub-tissue levels. It was observed that annulus fibrosus tissue level tensile properties and stress transmission mechanisms were dependent on specimen geometry. The model also demonstrated that the contribution of fiber–matrix interactions to tissue mechanical response was specimen size- and orientation-dependent. The results of this study reinforce the benefits of structure-based finite element modeling in studies investigating multiscale tissue mechanics. This approach also provides guidelines for developing optimal combined computational-experimental study designs for investigating fiber-reinforced biological tissue mechanics. Additionally, findings from this study help explain the geometry dependence of annulus fibrosus tensile mechanics previously reported in the literature, providing a more fundamental and comprehensive understanding of tissue mechanical behavior. In conclusion, the methods presented here can be used in conjunction with experimental tissue level data to simultaneously investigate tissue and sub-tissue scale mechanics, which is important as the field of soft tissue biomechanics advances toward studies that focus on diminishing length scales.

对生物组织力学的全面了解对于设计旨在概括天然组织行为的工程组织至关重要。研究表明，许多纤维增强组织的拉伸力学取决于试样的几何形状，这使得在研究之间比较数据具有挑战性。在这项研究中，经过验证的基于结构的多尺度有限元模型用于通过纤维啮合分析评估试样几何形状对多尺度环空纤维拉伸力学的影响。在组织和亚组织水平上研究了样品几何形状和模量，泊松比，组织应力-应变分布以及纤维重新定向行为之间的关系。观察到纤维环组织水平的拉伸特性和应力传递机制取决于样品的几何形状。该模型还表明，纤维-基质相互作用对组织机械反应的贡献取决于样品的大小和方向。这项研究的结果加强了在研究多尺度组织力学的研究中基于结构的有限元建模的好处。该方法还为开发用于研究纤维增强的生物组织力学的最佳组合计算实验研究设计提供了指导。此外，这项研究的发现还有助于解释先前文献中报道的纤维环张力力学的几何相关性，提供对组织机械行为的更基本和全面的了解。总之，此处介绍的方法可以与实验组织水平数据一起使用，以同时研究组织和亚组织尺度的力学，这一点非常重要，因为软组织生物力学领域正在朝着着重于减小长度尺度的方向发展。