基于机匣测点信号的航空发动机滚动轴承故障诊断灵敏性分析

Sensitivity analysis of fault diagnosis of aero-engine rolling bearing based on vibration signal measured on casing

研究了基于机匣测点信号进行航空发动机滚动轴承故障诊断的灵敏性问题.首先利用两个带机匣的航空发动机转子试验器进行了冲击响应试验,比较了滚动轴承处冲击激励引起的轴承座测点响应和机匣测点响应的差别;然后利用这两个带机匣的转子试验器进行了滚动轴承故障模拟试验,详细对比分析了轴承座测点信号和机匣测点信号的时域波形、频谱和小波包络谱.结果表明:当滚动轴承和机匣的连接刚度较小时,故障滚动轴承的振动信号传递到机匣上时会产生很大的衰减,然而利用传统的基于小波包变换的包络解调方法仍然可以很好地诊断出外圈故障和内圈故障,对于滚动体故障的诊断效果略差.研究结果对于实际中基于机匣测点信号进行航空发动机滚动轴承故障诊断提供了试验依据.

The sensitivity of fault diagnosis of aero-engine rolling bearing based on the vibration signal measured on the casing was studied.Firstly,the impulse response test was performed by two aero-engine rotor test rigs with casing.The response from both bearing housing and casing,which was caused by the impulse excitation from the location of rolling bearing,was measured and their differences were compared further.Secondly,the fault simulation test of rolling bearing was performed by these two aero-engine rotor test rigs.The time domain waveform,frequency spectrum and wavelet envelope spectrum of the signal measured on the casing were compared in detail with those of the signal measured on the bearing housing.The results show that when the coupling stiffness between rolling bearing and casing is small,there is a large attenuation of the vibration signal of faulty rolling bearing transmitted to the casing.However,by means of traditional envelope demodulation method based on wavelet transformation,the faults of outer and inner races still can be diagnosed well,but the diagnosis effect for rolling element is not as good as that for outer and inner races.The research results provide a test basis for actual fault diagnosis of aero-engine rolling bearing based on the vibration signal measured on the casing.