Investigation on Bearing Weak Fault Diagnosis under Colored Noise

For a bearing weak fault, it contains both periodic signals and a large amount of noise. The energy of the noise is large and its components are complex. It is difficult to obtain the early weak fault characteristics of bearing. In this paper, a typical Duffing system is improved by the generalized time transform and the method of changing the initial phase angle of built-in periodic strategy force. The developed method can be used to detect signal in a wider frequency band and the problem of misjudgment arising from Duffing system has been solved as well. According to the characteristics of the displacement output value variance of Duffing system, a method of bearing weak fault diagnosis is proposed. A high-intensity nonlinear colored noise has been introduced to disturb simulated weak fault signal, and then the weak fault signal has been diagnosed successfully by the proposed method. Under the condition of strong noise a kind of bearing inner ring fault has been diagnosed successfully. The proposed methods in this paper have certain theoretical and practical reference value.