旋转机械非平稳振动信号的时频分析比较

信号分析与处理是机械故障监测与诊断中故障提取的常用方法,传统的振动故障分析方法难以满足频率随时间变化的非平稳信号的要求,联合时频分析是非平稳信号比较有力的分析工具。以转子实验台的典型振动故障信号为研究对象,分析研究了几种时频分析方法如STFT、Wigner-Ville分布、小波变换和Hilbert-Huang变换。对比结果表明:STFT和Wigner-Ville分布的时频分辨率是矛盾的,易出交叉项或使信号变得微弱;小波分解会出现多余信号;Hilbert-Huang变换的时频分析能够直观检测信号中的微弱奇异成分,清楚给出时频分布情况,为旋转机械状态监测和故障诊断提供了新的手段。

Vibration signal's time-frequency analysis and comparison for a rotating machinery

It is important to extract fault features in fault diagnosis of a machinery. The traditional signal analysis can not be satisfactory for a non-stationary vibration signal whose statistical properties are time - variant. To deal with a non-stationary signal, time-frequency analysis techniques are widely used. Here, experiment clata of a typical vibration fault signal were analyzed with different methods, such as, short time Fourier transformation (STFT), Wigner-Ville distri-bution (WVD), Wavelet transformation (WT) and Hilbert-Huang Transformation (HHT). Comparing between these methods, it was demonstrated that the time-frequency resolutions of STFT and WVD were inconsistent, they were easy to work out cross terms or make the signal weaker; WT had a distinct time-frequency distribution, but it brought about re-dundant components; HHT time-frequency analysis could detect components with lower energy, and give a true and dis-tinct time-frequency distribution. Therefore, HHT is a very effective tool to diagnose early faults of a rotating machinery,and it provides new means for state detection and fault diagnosis.