风电机组叶根螺栓断裂失效分析

Fracture failure analysis on bolts in a wind turbine blade root

某型风电机组叶根固定螺栓发生断裂后,对断裂的螺栓进行外观检查,断口宏观、微观分析,化学成分分析,金相组织检查,力学性能及硬度检测及疲劳试验等。在理化试验的基础上,运用微观断裂机理对螺栓的断裂原因进行分析,确定其断裂形式为疲劳断裂,螺栓断裂的主要原因是螺纹缺口处的应力集中,导致疲劳源的产生,从而导致螺栓开裂。文章提出改善螺栓的加工工艺、改进设计、避免应力集中的建议,从而提高螺栓的抗疲劳断裂能力。

Some bolts on a wind turbine blade root were broken in service. Fracture analysis of those bolts was conducted by means of appearance examination, macro-fractograph and micro-fractograph analysis, chemical composition analysis, microstructure examination, rigidity testing and fatigue testing, etc. The results indicated that the fracture mode was fatigue failure. The fatigue fracture occurred in root of the screw with defects such as notches, and these defects made the zone to be a stress concentration area and caused the bolts to break finally. Ameliorating the machining processes of the bolts and improving the design to avoid stress concentration can help to improve the ability of defending fatigue fracture.