双谱分析及其在机械故障诊断中的应用

许多机械系统存在着明显的非线性特征，特别是当系统发生故障时，其非线性更加 突出。双谱分析是对非线性系统进行识别的有效方法。然而根据定义计算双谱，首先 要计算三阶相关函数．然后进行二维Ｆｏｕｒｉｅｒ变换．这需要大量的计算机机时。本 文在阐明双谱的概念的基础上，推导出利用ＦＦＴ快速算法估算双谱的公式，编制出计 算软件。最后利用双谱为析对２１００型柴油机连杆轴承出现的间隙非线性进行了分 析，正确地诊断出柴油机发生的故障。

Bispectral Analysis and Application in Machine Fault Diagnosis

The nonlinear features exist in many machine systems obviously. Especi-ally, when faults appear in the systems, the nonlinearity of the systems becomes prominent, Bispectral analysis is an efficient method in identification of nonlinear systems. However, calculating bispectrum from the definition of bispectrum, first the three order auto-correlation function must be calculated, then the two dimentional Fourier transformation may be carried out, This will take a long time of computer, The concept of bispectrum is described and the estimated formula worked out by means of FFT. The software of calculating bispectrum is made.The bispectral technique is applied to analysis of deadband nonlinearity occurring in the diesel type-2100. The fault of the diesel is correctly diagnosed,