Experimentally validated models for the prediction of fatigue damage progression and failure of conventional and green polymeric composites in aerospace and biomedical applications

自2005年以来，聚合物基复合材料（pmc）在现代飞机上的使用急剧增加，导致飞机性能和环境友好性的变化，已被证明是全球航空航天业的变革。这种快速的扩散，在为许多新应用（如本文提出的生物医学应用）敞开大门的同时，也要求开发分析模型，以帮助预测这些pmc的长期疲劳失效。后者是拟议研究计划的目标，该计划还将重点关注其新兴的生物医学应用。研究工作的目的是通过进行机械加载试验，并将所得结果与模型预测的结果进行比较，以确认所提出模型的有效性。研究将集中于两类pmc，即用于结构承重航空航天应用的合成纤维增强pmc和以亚麻纤维增强为重点的生物基（绿色）pmc。后者进一步解决了发展更环保的私人管理公司的迫切需要。具体目标包括开发基于广义微力学的疲劳失效预测模型，该模型结合了微力学与渐进连续损伤力学（CDM）和统计考虑的概念，开发计算软件以将所提出的疲劳模型实现为有限元解；以及各种PMC材料体系的实验表征，以确认所提出模型的准确性和通用性。一般的建模方法是通过微力学代表性体积单元（RVE）网络来表示基本层合板构建块（层合板），基于RVE在载荷作用下的行为来模拟层合板的破坏，并通过连续损伤力学方案预测层合板的性能退化和最终破坏。对于建议用于生物医学应用的亚麻纤维基复合材料，一般方法将包括其在温度、湿度和代表其预期生物医学应用的负载条件下的单向层状机械响应的实验表征。使用准确的预测模型的能力以及通过拟议的研究将产生的大量测试数据的可用性将产生对pmc性能的必要信心，并为其在未来轻型，节油和环保飞机中的更广泛应用铺平道路。在生物医学植入物方面，通过提出的研究计划所取得的进展将使这类先进材料更接近于在这个新兴的工程材料应用领域的广泛应用。

The use of polymer matrix composites (PMCs) in modern airplanes has dramatically increased since 2005, leading to changes in aircraft performance and environmental friendliness that have proven to be transformative within the worldwide aerospace industry. Such rapid proliferation, while opening the door wide for many new applications such as the biomedical ones proposed herein, also calls, among other things, for the development of analytical models that can help in the prediction of the long term fatigue failure of those PMCs. The latter is the aim of the proposed research program which will also focus on their emerging biomedical applications. The research effort will aim to confirm the validity of the proposed models by conducting mechanical loading tests and comparing the obtained results with those predicted by the models. The research will focus on two classes of PMCs, namely synthetic fiber-reinforced PMCs used in structural load bearing aerospace applications and bio-based (green) PMCs with a focus on those reinforced with flax fibers. The latter further addresses a pressing need to develop more environmentally friendly PMCs. The specific objectives include the development of generalized micromechanical-based fatigue failure prediction models that combine the concepts of micromechanics with progressive continuum damage mechanics (CDM) and statistical considerations, the development of computational software to implement the proposed fatigue models into Finite Element solutions, and the experimental characterization of various PMC material systems in order to confirm the accuracy and generality of the proposed models. The general approach for modeling is to represent the basic laminate building block (the lamina) through a network of micromechanical representative volume elements (RVE), model the failure of the lamina based on the behaviour of RVE under loading, and predict the property degradation and ultimately failure of the laminate through a continuum damage mechanics scheme. For the flax fiber based composites proposed for use in biomedical applications, the general approach will include the experimental characterization of their unidirectional laminae mechanical response under temperature, moisture, and loading conditions representative of their intended biomedical application. The ability to use accurate predictive models and the availability of the large amount of test data that will be produced through the proposed research will generate the necessary confidence in PMCs performance and pave the way to their wider use in the light weight, fuel efficient and environmentally friendly airplanes of the future, as well as biomedical implants where the advances made through the proposed research program will take this class of advanced materials one step closer to a widespread usage in this burgeoning area of engineering materials application.