航空发动机支架零件振动疲劳及结构优化

Vibration fatigue and structural optimization of aeroengine support part

针对某型航空发动机支架零件侧面根部经常出现疲劳裂纹的问题,基于功率谱密度(power spectral density,PSD)通过谐响应分析推导疲劳损伤传递函数,使用ANSYS Workbench搭建振动疲劳分析流程,结合模态信息使用Dirlik方法在nCode DesignLife中进行疲劳求解。仿真结果表明,该支架零件侧面根部的疲劳裂纹主要是由倒角半径过小导致的。发动机工作时可与支架零件产生2个共振带,虽然增大倒角半径有利于避开支架零件的2阶共振带,但是降低支架零件根部应力集中水平才是提高零件使用寿命的直接方法。当零件侧面根部倒角半径增大为2.5 mm时,支架零件的使用寿命最大。若配合零件背面根部倒角尺寸进行优化设计,可进一步提高零件的使用寿命。

As to the frequent fatigue cracks on the side root of an aeroengine support part,the fatigue damage transfer function is derived by harmonic response analysis based on power spectral density(PSD).ANSYS Workbench is used to simulate the vibration fatigue analysis process,and Dirlik method is used to solve fatigue in nCode DesignLife combining with modal information.The simulation results show that the fatigue cracks at the side root of the support part are mainly caused by the too small chamfer radius.During engine operation,two resonance bands appear on the support part.Although increasing the chamfer radius is beneficial to avoid the second order resonance band of the support part,but the direct way to improve the service life is reducing the stress concentration level at the root of the support part.While the side root chamfer radius increased to 2.5 mm,the service life of the support part is the maximum.While the chamfer size of the back part is optimized,the service life can be further improved.