阶比双谱及其在旋转机械故障诊断中的应用

双谱分析是处理非线性、非高斯信号的有力工具，然而，它是以分析恒频振动的稳态信号作为前提条件的，对分析旋转机械中广泛存在的变频振动信号（如旋转机械升降速信号）是无能为力的。而阶比双谱是一种分析变频振动信号的新方法，它将非稳态信号按等转角间隔进行采样，得到阶域中的稳定信号，再进行双谱分析；仿真显示该方法优于阶比谱和传统双谱。最后，将该方法成功地应用到旋转机械升降速过程的故障诊断中，实验结果表明该方法是有效的，阶比双谱可很好地分析机械振动的非线性非平稳信号。

ORDER BISPECTRUM AND ITS APPLICATION TO THE FAULT DIAGNOSIS OF ROTATING MACHINE

Bispectrum analysis, which is a useful tool for processing non-linear and non-Gaussian signal, is only adaptable to analyze steady-frequency signal, and incapable of analyzing variable frequency signal existing in the rotating machine widely, such as speed-up and speed-down signal. However the order bispectrum analysis, which is a powerful tool to process variable frequency signal, samples the unstable signal at the equal interval angular, and obtains the stable signal in the order domain, then calculate its bispectrum. The simulation shows that the order bispectrum analysis is superior to the traditional bispectrum. Finally, the order bispectrum is successfully applied to the speed-up and speed-down process of rotating machine, the experiment result shows the order bispectrum analysis can preferably process non-linear and non-stationary signal in the machine vabration.