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分析了非均匀接触下燕尾形榫头连接的应力状态 ,并借助于模拟试验 ,提出了非均匀接触导致疲劳破坏的基本痕迹特征。失效源位于叶片叶根截面中间段 ,裂纹朝叶片最大弯曲应力方向扩展 ,失效盘片接触处存在局部接触痕迹 ,接触区附近区域存在有微动损伤迹象。榫槽凸缘危险截面可能易于出现低周疲劳断裂。为避免非均匀接触导致的疲劳破坏 ,盘片燕尾形连接的实际接触面积 S应大于 Pb/( 2σ0 .2 sin α2 )。
The stress state of the dovetail joint under non-uniform contact is analyzed. Based on the simulation test, the basic characteristics of the fatigue damage caused by the non-uniform contact are proposed. The failure source is located in the middle section of blade root section, and the crack propagates toward the maximum bending stress of the blade. There is a local contact mark at the contact point of the failed disk. There are signs of fretting damage in the vicinity of the contact zone. Dangerous cross-section of tongue and groove flanges may be prone to low-cycle fatigue fracture. To avoid fatigue failure caused by non-uniform contact, the actual contact area S of the dovetailed disk should be larger than Pb / (2σ0 .2 sin α2).