海洋大气环境下粘贴CFRP材料补强含损伤钢板的疲劳性能

This study will be focused on the fatigue behaviour of Carbon Fibre Reinforced Polymer (CFRP) strengthened steel plates with centre cracks exposed to marine atmosphere. Exposure and fatigue experiments will be performed to quantify the effect of marine atmosphere on the fracture modes, failure mechanism and strengthening efficiency of CFRP bonded steel plates. Boundary Element Method based models will be developed to predict crack propagation and fatigue lives of the strengthened specimens and the results will be validated by the test data. Parametric analysis will also be conducted to establish S-N curves of the strengthened steel plates. Based on the Linear Elastic Fracture Mechanics theories, an approach for estimating stress intensity factors at crack tips of the strengthened steel plates with consideration of the influence of marine atmosphere will be put forward. The stress in the steel plates and the geometry correction factor which is used to represent the effect of non-uniform opening stress at crack surfaces will be evaluated. Finally, the numerical model and the theoretical approach can be used for the evaluation of the fatigue behaviour of CFRP strengthened steel plates with centre cracks exposed to marine atmosphere. This study will extend the understanding of CFRP repaired steel plates under harsh environmental conditions and provide some useful suggestions for the strengthening method, which will supplement the theoretical system of CFRP strengthened steel structures and also extend the application of the strengthening technique.

以海洋大气环境下粘贴碳纤维增强复合材料（CFRP）补强含损伤钢板的疲劳性能为研究对象，进行试验研究、数值模拟和理论分析。开展环境暴露试验和疲劳试验，探讨海洋大气环境及其关键参数对CFRP补强含损伤钢板试件在疲劳荷载作用下的破坏模式和失效机理的影响，揭示补强试件疲劳寿命的变化规律。采用边界元模拟方法，构建并验证精细化数值分析模型，实现考虑海洋大气环境作用的粘贴CFRP材料补强含损伤钢板疲劳性能的预测，并提出CFRP补强含损伤钢板的疲劳S-N曲线。基于线弹性断裂力学理论，计算补强体系中钢板应力和裂纹张开应力不均匀程度修正系数的变化，推导考虑海洋大气环境影响的粘贴CFRP材料补强含损伤钢板裂纹尖端应力强度因子计算方法。最终建立海洋大气环境下粘贴CFRP材料补强含损伤钢板疲劳性能评估方法。研究成果有助于完善CFRP材料补强钢构件理论体系，进一步推广CFRP材料在钢结构疲劳性能提升领域的应用。

粘贴碳纤维增强复合材料(CFRP)补强含损伤钢结构，能够有效降低损伤钢结构的局部应力，抑制疲劳裂纹扩展，延长疲劳寿命。目前对服役环境作用下的CFRP补强钢结构体系性能认识不足。本项目以海洋大气环境下粘贴CFRP补强含损伤钢构件为研究对象，进行试验研究、理论分析和数值模拟。开展环境暴露试验和疲劳试验，系统地研究了养护阶段海洋大气环境作用对粘结材料的影响、海洋大气环境、和疲劳荷载共同作用下CFRP-钢界面粘结性能，海洋大气环境作用对CFRP补强含损伤钢板疲劳性能的影响规律。发现结构粘胶养护阶段环境作用导致力学性能退化，和完好养护后长期暴露的影响相当，值得关注。海洋大气环境作用下CFRP-钢双面搭接节点和CFRP补强含损伤钢板试件未发生破坏模式的转变，认为性能退化主要由胶层性能退化引起。继而采用理论分析，基于退化的结构粘胶力学性能，对节点极限承载力和钢板疲劳性能进行预测。对CFRP-钢界面极限承载力预测模型不确定性展开全概率分析，把模型误差对输入参数的依赖性分离出来，将各类模型不确定性降低到同一水准。由此，采用统一折减系数即可到达设计可靠度，对工程应用具有重要意义。考虑到粘结体系在环境介质作用下的不确定性，进行了机械连接CFRP补强含损伤钢梁研究。比较了粘贴补强和粘贴补强并机械锚固两种体系的差异。给出了两种结构粘胶（线性/非线性）和两种机械锚固装置（相对柔性/刚性）的适用建议。试验中对疲劳荷载作用下CFRP-钢界面粘结性能进行定性分析。并采用数值模拟和理论分析对钢梁疲劳性能进行预测。采用边界元方法对CFRP补强含边裂纹和中心斜裂纹钢板疲劳性能进行模拟分析。研究成果有助于完善CFRP材料补强钢构件理论体系，进一步推广CFRP材料在钢结构疲劳性能提升领域的应用。