盐雾环境下高韧性聚氨酯基CFRP筋及其组合拉索的疲劳行为研究

The fatigue performance of carbon fiber reinforced low-toughness epoxy resin-based composites is relatively poor, which limits its application in some important engineering structures, such as coastal or cross-sea bridge cables. This project intends to study the fatigue behavior of high-toughness polyurethane (PU) -based CFRP bars and their combined cables under marine salt-spray environment. Firstly, the effects of the toughness of matrix on the basic mechanical properties, fatigue damage mechanism and fatigue life of CFRP bars will be studied. Secondly, the law and mechanism of water molecular absorption and diffusion, interface bond degradation of the high-toughness PU-based CFRP bars under marine salt-spray environment, and their effects on the fatigue damage and life of CFRP bars will be studied. Finally, based on the experimental tests and finite element analysis, the fatigue damage mechanism and life prediction model of the multiple PU-based CFRP bars combined cables will be investigated under marine salt-spray environment. This project will obtain the anti-fatigue stress design parameters of high anti-fatigue CFRP cable under marine salt-spray environment and promote the application of CFRP cable in bridge structures, which has important scientific research and engineering application significance.

碳纤维增强韧性较低环氧树脂基复合材料的疲劳性能相对较差，限制了其在一些重要工程结构（如沿海或跨海桥梁拉索）中的应用。本项目拟研究高韧性聚氨酯（PU）基CFRP筋及其组合拉索在海洋盐雾环境下的疲劳行为，主要包括，研究基体韧性对CFRP筋基本力学性能、疲劳破坏机理与疲劳寿命的影响；研究海洋盐雾环境下高韧性PU基CFRP筋的水分子吸收与扩散、界面粘结退化规律与机理，及其对CFRP筋疲劳损伤与寿命的影响；基于试验测试与有限元模拟分析，研究海洋盐雾环境下多根PU基CFRP筋组合拉索疲劳损伤机理，提出其疲劳寿命预测模型。本项目将获得高韧性PU基CFRP拉索在海洋盐雾环境下的抗疲劳应力设计参数，促进CFRP拉索在桥梁结构中的应用，具有重要的科学研究与工程应用意义。

环氧树脂基CFRP材料因其树脂基体韧性较低而表现出了相对较差的疲劳性能，限制了其在一些重要工程结构（如沿海或跨海桥梁拉索）中的应用。为此，本项目采用了韧性较高的聚氨酯（PU）代替传统的环氧树脂作为CFRP的树脂基体，并系统地研究了PU基CFRP的疲劳性能及其在典型土木工程恶劣服役环境下的演化规律与机理。取得的重要成果包括：获得了恶劣服役环境下PU基CFRP力学性能的演化与机理；提出了荷载与浸泡耦合作用下PU基CFRP的吸水机理模型，揭示了耦合作用对PU基CFRP力学性能的影响规律与机理，获得了其在典型沿海城市的长期服役寿命；获得了PU基CFRP的疲劳性能，建立了基于刚度退化的PU基CFRP疲劳寿命预测模型，揭示了不同应变水平下PU基CFRP疲劳寿命的演化规律；获得了恶劣服役环境下PU基CFRP疲劳性能的演化规律，揭示了其基于界面微观裂纹产生与发展的退化机理，建立了恶劣服役环境下PU基CFRP疲劳寿命的衰变模型。研究成果为PU基CFRP在土木工程领域中的应用奠定了坚实的理论与试验基础；同时，与环氧树脂基CFRP相比，PU基CFRP具有更优异的耐腐蚀性能和疲劳性能，其在土木工程领域中应具有更广阔的应用前景。