CAREER: Characterization and Simulation of Failure Mechanisms in Soft Fibrous Tissue

半月板是一种柔软的纤维组织，有助于保护膝盖的关节表面。在美国，半月板撕裂每年有超过50万人次去医院就诊。半月板和其他软组织的撕裂尚不清楚，因此很难预测它们何时会失败。如果不了解导致单个组织分子失效的微观事件，就很难创造出防止失效的方法。这项教师早期职业发展(Career)计划奖将增加软组织失败的科学知识，无论是一次还是多次加载。这项研究包括实验、理论和计算机预测方法，包括使用先进方法模拟软组织骨折。这个项目将使用研究开发的成像和预测为高中教育工作者创建一个计算机程序，它可以准确地模拟膝盖的损伤，可以在科学课堂上使用，以激励学生走向科学或医疗事业。这个研究项目的主要技术目标是建立和验证一个描述和预测人类半月板故障的计算模型。研究小组将在身体标本上进行准静态和疲劳破坏实验，以确定半月板骨折是否受胶原纤维排列和密度的影响。研究人员将在机械测试样本中测量细胞外基质的组织和组成，以直接将软组织微结构与失效行为联系起来。该团队还将开发数学模型，基于胶原纤维网络的应变能来预测断裂行为，并将使用这些模型来预测在年轻和老年半月板组织中观察到的实验失败。该项目将首次表征人类半月板的各向异性疲劳行为，并将第一次使用扩展有限元方法可视化半月板撕裂，以分割超过失效标准的区域。

The meniscus is a soft fibrous tissue that helps protect the joint surfaces in the knee. Meniscal tears account for over 500,000 hospital visits per year in the United States. The tearing of the meniscus and other soft tissues is not understood, making it difficult to predict when they will fail. Without understanding the microscopic events that cause failure of the individual tissue molecules, methods to prevent the failures are hard to create. This Faculty Early Career Development (CAREER) Program award will increase the scientific knowledge of failure in soft tissue when it is loaded either once or many times. This research includes experimental, theoretical and computer prediction approaches, including simulations of soft tissue fracture using advanced methods. This project will use the imaging and predictions developed from the research to create a computer program for high school educators that accurately simulates injury to the knee that can be used in science classes to motivate a student towards a scientific or medical career.The central technical objective of this research project is to build and validate a computational model that describes and predicts failure in human meniscus. The research team will perform quasi-static and fatigue failure experiments on cadaveric specimens to determine whether meniscal fractures are regulated by collagen fiber alignment and density. Researchers will measure the organization and composition of the extracellular matrix in mechanically tested specimens to directly link soft tissue microstructure to failure behavior. The team will also develop mathematical models to predict fracture behavior based on the strain energy of the collagen fiber network, and will use these models to predict the experimental failures observed in young and aged meniscal tissue. This project will be the first to characterize the anisotropic fatigue behavior of human meniscus, and will be the first to visualize meniscal tears using an extended finite element method to split regions that exceed failure criteria.