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基于航空发动机涡轮盘榫槽结构特点及其工作状态,采用榫槽模拟件对GH4720合金的疲劳失效机理和裂纹扩展寿命进行了实验研究和理论分析。研究结果表明:GH4720合金榫槽模拟件的疲劳失效表现为3个阶段:(i)模拟涡轮盘榫槽处由于较高的应力集中而产生滑移,进而萌生裂纹;(ii)随着应力集中和循环载荷的持续,相邻晶粒间位错开动、发生滑移,裂纹在晶粒间传递;(iii)随着应力强度因子范围增大,剪应力和主应力交互作用、滑移系开动及位错在不同滑移系间的运动,裂纹快速扩展。在实验基础上建立了GH4720合金的疲劳裂纹扩展寿命模型,基于有限元分析的榫槽处的应力和裂纹扩展寿命模型得到的裂纹扩展寿命与实验结果相符,表明该裂纹扩展寿命模型可用于工程中预测涡轮盘的剩余寿命。
Based on the characteristics of the mortise-tenon groove structure of aeroengine turbine disk and its working condition, the fatigue failure mechanism and the crack propagation life of GH4720 alloy were experimentally studied and theoretically analyzed by using tongue and groove simulator. The results show that the fatigue failure of the GH4720 alloy mortise and tenon simulator is characterized by three stages: (i) slip occurs at the mortise and tenon of the turbine disk due to high stress concentration, and then initiates cracks; (ii) And cyclic loads continue to occur, dislocations between adjacent grains start to slip, and the cracks propagate between grains. (Iii) As the range of stress intensity factor increases, the interaction between shear stress and principal stress causes the slip system to start And dislocation movement between different slip systems, the rapid expansion of the crack. The fatigue crack growth life model of GH4720 alloy was established on the basis of experiment. The crack propagation life obtained by stress and crack propagation life model based on finite element analysis is in good agreement with the experimental results, which shows that the crack propagation life model can be used in engineering Predict the remaining life of the turbine disk.