高强钢输电塔线体系腐蚀疲劳损伤的多尺度随机演化

Due to huge investment, severe environment of transmission line system and enormous losses after its failure, it is imperative to design and manage this system in the whole life-cycle, in which the evolution analysis of multiscale damage for transmission tower under complex environment and the Bayesian updating based on the inspection data are extremely critical parts. These parts becomes more important with the wide usage of high-strength steel (HSS)..Based on a lot of fatigue and corrosion fatigue experiments of high-strength steel members, bolt nodes and welded joints, the mechanism of their damage will be analyzed carefully, and the corresponding mechanical models are derived by the multiscale damage mechanics. Then introducing the multiscale modeling thought into both tower members and whole towers, a hybrid multiscale finite element model based on the substructure technique, which characterizes the property of transmission line system with HSS rationally, is proposed. Combining the probability density evolution method (PDEM) with the Bayesian theory, an extension of PDEM, which can incorporate the inspection data, is developed and used to analyze the multiscale stochastic evolution for damage of tower. Considering the nearly elasticity of tower under high cycle corrosion fatigue, an efficient method for compound random vibration based on the dimension-reduction method and virtual excitation method is put forward, which will be useful for simplized analysis of the stochastic evolution for damage. Finally, the researches above would built up the foundation for design, decision and management for transmission line system in life cycle.

输电线路投资巨大、灾害后果严重、使用环境恶劣等特点决定了必须开展全寿命周期设计和管理，其中杆塔在环境腐蚀和风致疲劳共同作用下损伤的多尺度演化分析及基于实测数据的Bayes更新是核心环节，高强钢的广泛应用进一步凸显了此环节的重要性。然而，输电线路领域的相关研究尚有待于进一步深入。本课题拟通过疲劳和腐蚀疲劳试验，分别研究高强钢杆塔典型节点及构件的损伤发展机理，并采用多尺度损伤力学建立腐蚀疲劳损伤演化模型；拟针对塔线体系的大系统特点，分别在杆塔整体层次和构件层次引入多尺度的建模理念，建立串并行混合多尺度有限元模型；结合概率密度演化理论和Bayes理论，实现杆塔损伤的多尺度随机演化及Bayes更新；利用高周腐蚀疲劳时杆塔结构近似线弹性的特点，发展基于降维近似模型和虚拟激励法的高效复合随机振动分析方法，实现杆塔腐蚀疲劳损伤随机演化的简化分析；最终为输电塔线体系全寿命周期的设计、决策和管理奠定基础。

输电线路投资巨大、灾害后果严重、使用环境恶劣等特点决定了必须开展全寿命周期设计和管理，其中杆塔在环境腐蚀和风致疲劳共同作用下损伤的多尺度演化分析及基于实测数据的Bayes更新是核心环节，高强钢的广泛应用进一步凸显了此环节的重要性。然而，输电线路领域的相关研究尚有待于进一步深入。为此，本项目针对输电塔线体系腐蚀疲劳累积损伤随机分析展开研究。首先，开展了输电塔高强钢试件、节点、材料的疲劳和腐蚀疲劳系列试验，建立了高强钢试件、节点的疲劳和腐蚀疲劳S-N寿命模型，并结合断裂力学与损伤力学推导了高强钢的腐蚀疲劳损伤演化模型。其次，针对输电塔线体系的大系统特点，建立了兼顾整体层次和构件层次的输电塔线体系串并行混合多尺度有限元模型，并将其与腐蚀疲劳损伤演化模型相结合，实现了输电塔线体系腐蚀疲劳损伤演化的有限元模拟。再次，结合概率密度演化理论与Bayes更新理论，提出了考虑Bayes更新的概率密度演化方法，并将其与腐蚀疲劳损伤的多尺度有限元模拟相结合，实现了高强钢输电塔线体系腐蚀疲劳损伤的多尺度随机演化的精细化分析；与此同时，考虑到高周腐蚀疲劳时杆塔结构近似线弹性特点，结合高效的降维近似统计矩估计与基于虚拟激励法的高效随机振动分析，发展了高效的复合随机振动分析方法，并实现了杆塔腐蚀疲劳损伤多尺度随机演化的简化分析；最后，结合不同服役时间输电塔的腐蚀疲劳损伤状态，分别采用矩方法和响应面法进行了服役杆塔的可靠度状态评估，为输电塔线体系全寿命周期的设计、决策和管理奠定了基础。