基于高低周复合疲劳试验技术的叶片失效故障复现

Blade Failure Recurrence Based on High-Low Cycle Complex Fatigue Experimental Technique

针对某涵道尾桨风扇叶片在风洞试验中发生的断裂故障,基于叶片破坏模式和载荷形式,初步分析为离心载荷/低循环疲劳(LCF)和气动载荷/高循环疲劳(HCF)耦合作用导致的疲劳破坏。基于此,通过正交载荷解耦和协调加载控制等关键技术开展联合载荷作用下的叶片复合疲劳(CCF)试验技术研究和试验考核验证。试验结果表明,离心载荷控制精度优于±1%,气动载荷控制精度优于±8‰。试验应变响应频率与试验加载频率一致性较好,满足试验加载和控制的同步性要求。最终,通过对叶片故障复现验证失效原因分析的正确性,为叶片结构优化设计、寿命评估和复合疲劳试验奠定技术基础。

Considering on the failure mode and load type of blade,it can be preliminarily inferred that the fracture failure of a certain type of ducted tail rotor fan blade which occurred in wind tunnel experiment resulted from the coupling effect of centrifugal load/Low Cycle Fatigue(LCF)and aerodynamic load/High Cycle Fatigue(HCF). Based on this,the Combined Cycle Fatigue(CCF)experimental technique on combined loads of blade was investigated and verified by means of the critical technologies of orthogonal loads decoupling and coordinated loading control. The results show that the control precision of centrifugal load is superior than ±1%,and the control precision of aerodynamic load is superior than ±8‰. The frequency of the strain response is consistent with the frequency of load,which satisfies the requirements of the synchronization of loading control. Finally,the validity of failure analysis is verified by blade failure recurrence,which lays the technical foundation for structural optimization design,fatigue life evaluation and CCF experiment of blade.