Predicting the Lifetime of Polymer Pipes in Corrosive Environments

预测腐蚀环境中聚合物管道的使用寿命

• 批准号: 1462080
• 负责人: Susan Mantell
• 金额: $ 36.53万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-15 至 2019-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1462080&HistoricalAwards=false
• 关键词: Predicting; Lifetime; Polymer; Pipes; Corrosive

Low cost polymers are increasingly used for civil infrastructure applications such as pipes for water and natural gas delivery, corrugated drainage pipes, sanitation pipes, and geomembranes. In these applications, the combination of mechanical loading and environmental conditions can accelerate degradation of the polymer and lead to crack formation and propagation referred to as stress corrosion cracking (SCC). The main feature of SCC is the evolution of multiple small cracks with failure ultimately occurring when one of these cracks propagates. The lifetime of polymer components can vary significantly due to the randomness of mechanical and transport properties of polymer materials. In this project, a numerical model will be developed that combines the fracture behavior with the diffusion of the liquid environment and subsequent degradation of the polymer. A series of experiments will be performed in which the mechanical properties of the polymer are characterized as a function of polymer degradation. The statistical variation in these properties is the cornerstone for predicting the variability in polymer lifetime. This research will advance our understanding of probabilistic SCC in polymers. In addition, it will provide engineers a scientific method to design polymer pipes for a prescribed failure risk, which will improve the structural reliability of pipes used for civil infrastructure applications. The educational plan includes activities targeted for a range of constituents at various levels of expertise: a high school camp that utilizes a web-based tool for pipe design, webinars for polymer industry professionals, and university courses for undergraduates and graduate students. As compared to existing approaches for design of polymer components, which are primarily based on a deterministic framework, this research is anchored by a probabilistic framework. By including the effects of uncertainties in various material properties (i.e., mechanical properties, chemical diffusivity and molecular weight), the model can capture the overall stochastic response of polymers in a corrosive environment. This research will lead to the following important results: 1) a stochastic chemo-mechanical model for SCC in polymers that characterizes the interactions between the chemical diffusion process, chemical-induced material degradation and crack propagation; 2) a methodology and experimental data to quantify the relationship between degradation of mechanical properties and molecular weight; 3) model validation through an experimental study of crack growth in a corrosive liquid environment; and 4) a reliability-based design method for polymer pipes, which will allow engineers to design pipes for a desirable lifetime at a tolerable failure risk.

低成本聚合物越来越多地用于民用基础设施应用，如水和天然气输送管道、波纹排水管、卫生管道和土工膜。在这些应用中，机械载荷和环境条件的结合会加速聚合物的降解，导致裂缝的形成和扩展，即应力腐蚀开裂（SCC）。SCC的主要特征是多个小裂纹的演化，当其中一个裂纹扩展时最终发生破坏。由于聚合物材料的机械和输运特性的随机性，聚合物组件的寿命可能会有很大的变化。在这个项目中，将开发一个数值模型，将破裂行为与液体环境的扩散和随后的聚合物降解结合起来。将进行一系列的实验，其中聚合物的机械性能被表征为聚合物降解的功能。这些性质的统计变化是预测聚合物寿命变化的基础。这项研究将促进我们对聚合物中概率SCC的理解。此外，它将为工程师提供一种科学的方法来设计规定失效风险的聚合物管道，这将提高用于民用基础设施应用的管道的结构可靠性。教育计划包括针对不同专业水平的组成部分的活动：利用网络工具进行管道设计的高中营地，聚合物行业专业人员的网络研讨会，以及面向本科生和研究生的大学课程。与现有的主要基于确定性框架的聚合物组件设计方法相比，本研究基于概率框架。通过考虑各种材料性能（即机械性能、化学扩散率和分子量）的不确定性的影响，该模型可以捕捉聚合物在腐蚀性环境中的整体随机响应。本研究将导致以下重要结果：1)聚合物中SCC的随机化学力学模型，表征化学扩散过程、化学诱导材料降解和裂纹扩展之间的相互作用；2)一种量化力学性能退化与分子量关系的方法和实验数据；3)通过腐蚀液体环境下裂纹扩展的实验研究验证模型；4)基于可靠性的聚合物管道设计方法，这将使工程师能够在可容忍的失效风险下设计出理想的使用寿命。