风力发电机组叶片连接螺栓断裂机理及原因分析

Fracture Mechanism and Cause Analysis of Connecting Bolts for Wind Power Turbine Blades

利用宏观形貌、金相显微组织与断口形貌观察、化学成分分析及力学性能检测等方法对某风力发电机组叶片连接螺栓的断裂机理及原因进行了研究。结果表明,叶片连接螺栓的断裂主要与复杂应力共同作用引发的疲劳工况有关。在风机运行过程中,径向和轴向等多方向剪切力的共同作用使得叶片法兰与变桨轴承结合面的螺纹牙底处逐渐形成疲劳裂纹源,并在应力集中的作用下加速扩展引发了螺栓的疲劳断裂失效。最后对在役叶片连接螺栓的使用维护及更换提出了建议。

In this paper,the fracture cause and mechanism of the connecting bolts of a wind turbine blade are investigated by means of macro morphology,metallographic microstructure and fracture morphology observation,chemical composition analysis as well as mechanical property test.The results show that the fracture of the two blade connecting bolts is mainly related to the fatigue condition caused by complex stress.During the operation of the wind turbine,fatigue crack sources are gradually formed at the thread bottom of the joint surface between the blade flange and the pitch bearing under the combined actions of radial and axial shear forces.Under the effect of stress concentration,the accelerated growth eventually leads to the fatigue fracture failure of the bolt.At last,some suggestions about operation,maintenance and replacement of the in-service blade connecting bolts are put forward.