主桨毂中央件限动锁连接螺栓提前断裂原因分析

主桨毂中央件疲劳试验限动锁连接螺栓出现提前断裂故障，通过断口宏观形貌、微观组织、断口特征、硬度等分析方法，得出故障件的断裂性质为单向弯曲疲劳断裂，产生原因与螺栓拧紧力矩降低、螺栓头部倒角过渡区域加工质量有关。通过增大限动锁连接螺栓拧紧力矩、螺纹及螺栓头部R区进行倒圆弧滚压强化等改进措施，主桨毂中央件限动锁连接螺栓在疲劳试验全过程中未再发生提前断裂。

Analysis of Premature Fracture of Connection Blots of Limited Lock for Central Component of Main Hub

The phenomena of premature rupture of connecting bolt of restriction lock in fatigue test of a main hub central component are investigated through the analysis of macro-morphology, micro-structure, fracture characteristics and hardness testing. It is concluded that the fracture property of the failure part is unidirectional bending fatigue rupture which are caused by the reduction of bolt tightening moment and the processing quality of the transition area of chamfering angle of the bolt head. According to the analysis of the fault results, propose improvements are as follow: increasing the tightening moment of the locking bolt, increasing strength by the screw thread and the R area of the bolt head inverted arc rolling. The connecting bolt of the restriction lock of the central part of the main propeller hub is improved by the above measures, and no early fracture occurred during the entire fatigue test.