Role of Fiber-matrix Interactions During Failure in Fiber Reinforced Tissues

全身的许多生物组织都是纤维增强的复合材料，主要由水、胶原纤维和柔软的纤维外基质组成。这些组织的失败或撕裂会导致疼痛和残疾。组织的组成和分子结构对组织在生理负荷和失效过程中的力学性质都是重要的。到目前为止，还没有足够的研究集中在分子水平的破坏机制的纤维增强组织，如脊柱的间盘。确定组织失效特性和组织的各种分子在失效行为中所起的作用对于预防椎间盘疾病和设计修复椎间盘的新的医学方法是重要的。该项目的目标是确定纤维增强组织结构如何控制损伤力学。在这项工作中，PI将专注于椎间盘的纤维环，因为它的交叉层纤维结构和医学相关性。该项目的教育推广工作是由伯克利工程学院协调的工程女孩(GIE)暑期计划的扩展。在执行研究项目期间，PI还将在她的实验室培训来自不同背景的研究生和本科生。在这个项目中，PI将评估纤维外基质组成、纤维组成和网络对时间相关和独立失效行为的作用。她将结合计算和实验技术来研究纤维增强材料的失效机制，例如纤维和纤维外基质之间的应力分布。她的研究团队将利用他们之前的工作，开发出一种实验方法，对纤维环进行稳健的故障测试。来自组织水平实验的数据将被合并到现有的椎间盘关节的有限元模型中，以阐明纤维-基质相互作用在关节水平失效中的作用。从更广泛的意义上说，从这项研究开发的独特计算模型，其中纤维外基质和胶原纤维被描述为独立的和不同的材料，将有益于生物力学研究以外的材料科学家(例如，碳纤维增强聚合物)，以及研究纤维和纤维外基质对组织力学(亚失效和失效力学)与损伤、老化或修复的贡献的科学家。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Many biological tissues throughout the body are fiber-reinforced composites, built primarily of water, collagen fibers, and a soft extrafibrillar matrix. Failure or tearing of these tissues causes pain and disability. Tissue composition and molecular architecture are important to the tissue mechanical properties both during physiological loading and during failure. To date, there has been insufficient research focused on molecular level failure mechanics of fiber-reinforced tissues such as the intervertebral discs of the spine. Determining tissue failure properties and the roles that the various molecules of the tissue play in failure behavior is important for preventing disc disease and to designing new medical approaches for repairing the disc. The goal of this project is to determine how the fiber-reinforced tissue structure controls damage mechanics. For this work the PI will focus on the annulus fibrosus of the intervertebral disc because of its cross-ply fiber architecture and medical relevance. The educational outreach effort in this project is an expansion of the Girls in Engineering (GiE) Summer Program coordinated by the College of Engineering at Berkeley. The PI also will train graduate and undergraduate students from diverse backgrounds in her laboratory during performance of the research project. In this project, the PI will evaluate the role of the extrafibrillar matrix composition and fiber composition and network on time-dependent and -independent failure behavior. She will combine computational and experimental techniques to study failure mechanisms of fiber-reinforced materials, such as stress distributions between fibers and the extrafibrillar matrix. Her research team will leverage its previous work that developed an experimental method for robust failure testing of the annulus fibrosus. Data from tissue-level experiments will be incorporated into the existing finite element model of the disc joint to elucidate the role of fiber-matrix interactions during joint-level failure. In broader terms, the unique computational model developed from this research, where the extrafibrillar matrix and collagen fibers are described as separate and distinct materials will be beneficial for material scientists outside of biomechanics research (e.g., carbon fiber reinforced polymers) and for scientists investigating the contribution of fibers and extrafibrillar matrix on tissue mechanics (sub-failure and failure mechanics) with injury, aging, or repair.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.