Investigation On Failure Mechanism And Shift Orbits Recognition Methods For Rotating Machine

As a kind of important graphic signs, shift orbit includes lots of fault information. Thus, the shift orbit is indispensable fault information in the diagnosis process.Based on the investigation abroad and in broad, this paper focused on two aspects:1)Study the fault mechanism of ordinary failure which afford theory foundation for shaft orbits recognition; 2) Classify the shift orbits by using information fusion technology named as D-S evidential theory. Simulation experiments and practical signals were used to testify the effectiveness of this method.The organization of this research is as following:Firstly, time and frequency domain characteristics together with failure mechanism of two channel signals for constructing shift orbit are investigated. The sliding bearing-rotor system fault models with nonlinear stiffness of common failure, such as imbalance, misalignment, bearing loosen, rub-impact, and pedestal looseness-rub impact fault, are constructed respectively. Fourth-order Runge-Kutta numerical simulation method is used to analyze the failure mechanism and the influence for system, especially on the shift orbit by the change of parameters in each system.Time and frequency domain features are investigated for condition classification. At the same time, shift orbit characteristics are investigated in detail.Then, a shift orbit shape feature extraction technique based on the two-dimensional moment invariants and Fourier descriptors is proposed in order to extract the image feature. Five common shift orbit graphics are simulated by Matlab, and regarding seven moment invariants within two-dimensional and eight Fourier descriptors as a reference model.Taking advantage of the information fusion technology, D-S evidential theory is used to identify the shift orbits.The steps of shift orbits recognition algorithm are described by this method. Compared with the traditional Euclidean distance classification, this method has good performance on effectiveness.According to above investigation, the common fault conditions are simulated through the experiment on the ZT-3 multi-functional rotor test-rig. The results can verify the correctness of this new method.At the same time, the shift orbits of the experiments and practical testing signals in industry are used to testify this method.