Collaborative Research: Fatique and Lifetime Performance of Polymer Sandwich Constructions -A Multi-Scale Experiment and Modeling Approach

合作研究：聚合物夹层结构的疲劳和寿命性能 - 多尺度实验和建模方法

• 批准号: 1265691
• 负责人: Valeria LaSaponara
• 金额: $ 18.5万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1265691&HistoricalAwards=false
• 关键词: Collaborative; Research; Fatique; Lifetime; Performance

Polymer foam core sandwich composites have been utilized for modern marine vessels, civil infrastructures and large wind turbine blades. These structures experience continuous cycles of loadings and continuous exposure to hostile environments, which could lead to degradation in the materials and structural failures. Our aim is to predict the time when global failure starts, and its critical location in the sandwich structures during their service. This will be achieved through the development of material and structural models for the sandwich structures that incorporate the time-dependent mechanical loadings coupled with thermal and moisture diffusion, and degradation in the properties of the constituents. A comprehensive testing scheme including accelerated fatigue tests will be conducted on the sandwich composite and its constituents at different loading histories and various moisture and temperature conditions. The experimental results will be used to characterize the material parameters in the time-dependent (creep) material model, hygro-thermal diffusions, and degradation model for each component of the sandwich structures and verify the prediction of the time and mode when fatigue failure initiates in the sandwich structures. The thick and multi-layered nature of sandwich structures lead to multiple failure mechanisms, which can be difficult to detect from their surfaces. Currently, fatigue failure in sandwich composites has been determined mainly by counting the number of repeated loading cycles until overall failure is observed in the composites without any explanation on the failure mechanisms and consideration of the environmental conditions. The results of this study will significantly improve our understanding on the life performance and fatigue failure mechanisms in many structures and infrastructures made of polymer sandwich composites undergoing mechanical loadings while being exposed to hostile environments. The research outcomes will help engineers in improving the design of structures/infrastructures made of these composites in order to avoid catastrophic failures. This information can also help manufacturers and researchers designing better quality polymeric composites. The proposed modeling concept will address the above challenges, which will enhance the reliability of polymeric sandwich structures and hence public safety.

聚合物泡沫芯夹层复合材料已用于现代船舶、民用基础设施和大型风力涡轮机叶片。这些结构经历连续的载荷循环和持续暴露于恶劣环境，这可能导致材料降解和结构失效。我们的目标是预测全局失效开始的时间，以及其在使用期间在夹层结构中的关键位置。这将通过开发夹层结构的材料和结构模型来实现，该模型将随时间变化的机械载荷与热和湿气扩散以及成分性能的退化相结合。将在不同的加载历史和各种湿度和温度条件下对夹层复合材料及其成分进行包括加速疲劳测试在内的综合测试方案。实验结果将用于表征夹层结构每个部件的时间相关（蠕变）材料模型、湿热扩散和退化模型中的材料参数，并验证对疲劳失效开始时的时间和模式的预测在夹层结构中。夹层结构的厚和多层性质导致多种失效机制，很难从其表面检测到。目前，夹层复合材料的疲劳失效主要通过计算重复加载循环的次数直至观察到复合材料的整体失效来确定，而没有对失效机制进行任何解释并考虑环境条件。这项研究的结果将显着提高我们对许多由聚合物夹层复合材料制成的结构和基础设施的寿命性能和疲劳失效机制的理解，这些结构和基础设施在暴露于恶劣环境时承受机械载荷。研究成果将帮助工程师改进由这些复合材料制成的结构/基础设施的设计，以避免灾难性故障。这些信息还可以帮助制造商和研究人员设计质量更好的聚合物复合材料。所提出的建模概念将解决上述挑战，这将提高聚合物夹层结构的可靠性，从而提高公共安全。