空冷风机-结构耦合系统微动疲劳可靠性研究

空冷技术显著的节水优势使其得到了业界广泛的关注和应用。风机振动导致高强螺栓连接部位发生微动疲劳损伤和断裂是长期运行过程中空冷结构的主要失效模式。在现场实测结构振动响应的基础上，建立风机叶片-结构相互作用模型，采用倒向概率密度演化方程构建风机扰力随机函数模型。通过微动疲劳试验和断口扫描电镜观察建立高强螺栓连接板的概率微动疲劳寿命模型，揭示其微动疲劳损伤演化机理，并基于有限元模拟进行微动疲劳寿命主要影响因素的参数分析。进而，采用疲劳损伤概率密度演化方法开展耦合结构可靠度分析，提出工程设计方法。预期研究成果对保障空冷结构长期运行安全具有重要的工程应用价值。同时，对于拓展振动设备-结构耦合建模方法、丰富荷载反演理论和微动疲劳损伤可靠度方法具有重要的科学意义。

Air-cooling technique is widely used in power plants due to its great advantage for water conservation. In the long term service of an air-cooling structure，the fretting fatigue damage and fracture induced by the vibration of mechanical fans are its major failure mechanisms. On the basis of recorded structural responses， blade/structure coupled FEM models will be established， and a stochastic function model for disturbing forces of the fans will then be developed via the inverse probability density evolution equation. Moreover，we are going to conduct fretting fatigue tests and SEM observation to develop the P-S-N life model and discover the fatigue damage and failure modes for bolted connections. FEM simulation will be employed to analyze the factors affecting the fretting fatigue life. In addition，fretting fatigue reliability of the coupled air-cooling structure will be evaluated in terms of the fatigue damage evolution method， and corresponding design method will also be proposed. The expected findings would provide not only a scientific method for the engineering design of air-cooling structures， but also new ways to fulfill vibration equipment-structure modelling，load inversion and fretting fatigue damage evaluation.