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对平圩发电有限公司两台引进型 60 0 MW汽轮机“4 74”叶片、叶根、轮缘事故原因作了分析 ,认为叶片断落的原因主要由于单节线扭振共振、加之某些缺陷引起的应力集中所致 ;叶根、轮缘裂纹的原因 ,主要由于该级叶根设计单薄、强度裕量小 ,诸多因素造成叶根齿受力状况的变化 ,使叶根齿局部应力过大、二阶频率下降落入共振的边缘 ,加之应力集中、过渡区腐蚀环境的影响等 ,使叶根安全裕度下降、累积疲劳所致。
The causes of the blade, root and rim accidents of “74” blades of two imported 60 MW turbines in Pingwei Power Generation Co., Ltd. were analyzed. The reason of blade failure was mainly attributed to the single-section torsional vibration resonance with some defects Caused by the stress concentration; leaf root, rim cracks, mainly due to the level of the root design is thin, strength margin is small, many factors that cause changes in leaf root stress, so that the local root tip stress is too large , The second-order frequency falls into the edge of the resonance, combined with stress concentration, the impact of the transition zone corrosive environment, so that leaves the safety margin decreased, cumulative fatigue.