摘要
在叶轮旋转过程中,位于风机叶片根部用于紧固的连接螺栓因受到周期性的弯曲应力而容易疲劳。弯曲疲劳是造成螺栓松弛、损伤甚至断裂的重要原因。本研究以某风电厂2 MW风机高强连接螺栓为研究对象,利用PQ1-6弯曲疲劳试验机开展螺栓试样的旋转弯曲试验研究;通过宏观分析、化学成分分析、显微组织检测及扫描电子显微镜断口微观分析等方法,探究试验过程中螺栓材料的组织演变规律,研究螺栓失效的微观机理及其疲劳损伤的发展过程。结果表明:在250 N的负荷下螺栓的旋转弯曲疲劳寿命为76200周次;由旋转弯曲疲劳载荷引起的螺栓试样组织演变和疲劳损伤累积呈全域性分布特点,并在螺栓试样材料的不同部位形成了疲劳影响带,且其距离断口越近材料组织的疲劳损伤程度越大;疲劳损伤带由表及里向试样内部扩展;断口处疲劳裂纹从试样表面开始萌生,断裂机理为韧性断裂;螺栓材料中的夹杂物加剧了弯曲疲劳裂纹的集中和扩展,进一步缩短了螺栓的疲劳寿命。
In the process of impeller rotation,the fastening connecting bolts at the blade root of the wind turbine are prone to fatigue due to the periodic bending stress.Bending fatigue is an important cause of bolt relaxation,damage and even fracture.In this study,the high-strength connecting bolts of a 2 MW wind turbine in a wind farm were taken as the research object.The rotating bending test of bolt specimen was carried out by using PQ1-6 bending fatigue testing machine,at the same time,through macroscopic analysis,chemical composition analysis,microscopic structure detection,scanning electron microscope(SEM)fracture microanalysis and other methods,the structure evolution of bolt materials was explored in the test process,and the microscopic mechanism of bolt failure and the development process of fatigue damage were studied.The results show that the rotating bending fatigue life of the bolt is 76200 cycles under 250 N load.The microstructure evolution and fatigue damage accumulation of the bolt specimen caused by rotating bending fatigue load show a regional distribution characteristic,the fatigue influence zone is formed in different parts of the bolt specimen material,and the closer it is to the fracture,the greater the fatigue damage degree of the material tissue is.The fatigue damage zone extends from the surface to the interior of the specimen.The fatigue crack begins from the surface of the specimen and the fracture mechanism is ductile fracture.The inclusions in bolt material a ggravate the concentration and propagation of bending fatigue cracks,and further shorten the fatigue life of bolts.
作者
陈标
何建军
程庆阳
蒲珉
揭军
刘明宇
朱琪
CHEN Biao;HE Jian-jun;CHENG Qing-yang;PU Min;JIE Jun;LIU Ming-yu;ZHU Qi(Longyuan Jiangyong Wind Power Generation Co.,Ltd.of CHN Energy Group,Changsha 410000,China;School of Energy and Power Engineering,Changsha University of Science&Technology,Changsha 410114,China;Xi'an Zhongke Qihang Monitoring and Control Technology Co.,Ltd.,Xi'an 712000,China)
出处
《长沙理工大学学报（自然科学版）》
CAS
2021年第3期105-110,共6页
Journal of Changsha University of Science and Technology:Natural Science
基金
湖南省自然科学基金资助项目(2019JJ40304)。
关键词
风力发电机叶片
旋转弯曲疲劳
高强螺栓
疲劳试验
显微组织
wind turbine blade
rotating bending fatigue
high-strength bolt
fatigue test
microscopic structure
