Nonlinear Fracture Mechanics of Hydrogel-Like Soft Materials

水凝胶状软材料在自然界中丰富，包括软组织，如软骨、肌腱和韧带。合成聚合物基水凝胶具有相似的机械性能和生物相容性，已被广泛用于各种生物医学应用，如人工组织和药物递送。最近，水凝胶状材料已被探索作为一类软活性材料在软机器和软机器人的发展。对于许多这些应用，水凝胶状软材料的机械性能是重要的，决定了它们在各种条件下如何变形和失效。特别是，水凝胶状软材料的断裂尚未得到很好的理解，预测这种材料是否以及何时断裂仍然是一个挑战。本项目旨在建立水凝胶类软材料失效分析和预测所需的知识库。这些结果将使这种材料的工程具有可靠的断裂性能，适用于包括组织工程和软机器人在内的一系列应用。这三位PI将与断裂力学/动力学、软材料、实验、建模和模拟方面的专业知识合作，为该项目带来不同的视角。教育和推广活动将被纳入该项目，以提高其更广泛的社会影响，其中包括本科生的研究经验，从事少数民族和代表性不足的群体，并推广到高中生和广大公众。水凝胶类软材料的断裂过程是高度非线性的一般，耦合大变形与特定的动力学过程，由于溶剂扩散和聚合物粘弹性。该项目是建立一个非线性的，瞬态的理论框架，定义的断裂驱动力和断裂准则的裂纹扩展的水凝胶状软材料，明确识别相关的动力学过程。该理论框架将实现数值模拟，预测与水凝胶类材料相关的特定断裂行为，如延迟断裂和速率依赖性。将结果与实验测量值进行比较，以进行验证。开发的建模和实验方法，然后将用于测量水凝胶状软材料的断裂性能。溶剂扩散和粘弹性对断裂的不同影响将通过数值模拟和一组从准静态到动态的实验来阐明。

Hydrogel-like soft materials are abundant in nature including soft tissues such as cartilage, tendons and ligaments. With similar mechanical properties and biocompatibility, synthetic polymer-based hydrogels have been used extensively for a wide range of biomedical applications such as artificial tissues and drug delivery. More recently, hydrogel-like materials have been explored as a class of soft active materials in the development of soft machines and soft robotics. For many of these applications, mechanical properties of the hydrogel-like soft materials are important, governing how they deform and fail under various conditions. In particular, fracture of hydrogel-like soft materials has not been well understood, and it remains a challenge to predict if and when such materials would fracture. This project aims to establish a knowledge base necessary for failure analysis and prediction of hydrogel-like soft materials. The results will enable engineering of such materials with reliable fracture properties for a range of applications including tissue engineering and soft robotics. The three PIs, jointly with expertise in fracture mechanics/dynamics, soft materials, experiments, modeling and simulations, will collaborate to bring different perspectives onto this project. Education and outreach activities will be integrated within the project to enhance its broader societal impacts, which include research experience for undergraduates, engaging minorities and underrepresented groups, and outreach to high school students and general public.The fracture processes of hydrogel-like soft materials are highly nonlinear in general, coupling large deformation with particular kinetic processes due to solvent diffusion and polymer viscoelasticity. This project is to establish a nonlinear, transient theoretical framework that defines the fracture driving force and a fracture criterion for crack growth in hydrogel-like soft materials, with explicit recognition of the associated kinetic processes. The theoretical framework will enable implementation of numerical simulations that would predict particular fracture behaviors relevant to hydrogel-like materials such as delayed fracture and rate dependence. The results will be compared to experimental measurements for validation. The developed methodology with modeling and experiments will then be used for measuring fracture properties of hydrogel-like soft materials. The distinct effects of solvent diffusion and viscoelasticity on fracture will be elucidated through numerical simulations and a set of experiments from quasistatic to dynamic regimes.