Study On Some Nonlinear Dynamics Problems Of Rotating Machinery At High Speed & Fault Diagnosis Methods

Rotating machinery at high-speed is widely used in many fields. For many accidents of rotating machinery at high speed have caused serious effects on our country and companies. At the same time, with the development of science technology, rotating machinery is more high-speed, lighter, high-efficiency and more intellective, so it is necessary to carry out monitor and diagnosis. In this paper, the rotating machinery at high speed is studied. There are discussed about numerical calculating methods for non-linear dynamical system, the rotor system radial impact and rubbing dynamics behavior analysis having the nonlinear rigidity on the unsteady and non-linear oil film, the rotor system dynamics behavior analysis with bending-torsional-pendular coupling vibrations, application of wavelet, fractal and network in fault diagnosis. The main works in this paper are as follows:(1). In this thesis, a new method, continuous linearization model, is constructed for the non-linear dynamic systems. The precision Duhamel integration solution for the linearization equation is also given from the theory of linear differential equation. The calculating results show that the new method can improve the calculation precision greatly. In fact, the truncation error is not limited by this method, it can arrive the precision according to the requirement.(2). It is constructed that radial impact and rubbing dynamics differential equations of the rotor system having the nonlinear rigidity on the unsteady and non-linear oil film. The bifurcation and chaos behavior of impact and rubbing fault rotor system caused by the parameters of nonlinear rigidity, rotor rotating speed, eccentric mass is analyzed, in the numerical value analysis method. The bifurcation diagrams, maximum Lyapunov exponent diagrams, Poincarémaps, phase plane portraits, trajectories of journal center, time-history curve, amplitude spectra diagrams of the rotor motion are used. The convert and evolution course of periodical response, quasi-periodical response, double-periodical bifurcation, chaos of the system response is analyzed.(3). It is deduced that the general differential equation of bending-torsional- pendular coupling vibration about rotor with the gyroscopic moment. On the basis of this equation, the general differential equations of coupled bending, torsional and pendular nonlinear vibration about rotor with unbalance character and rubbing character are deduced. The bifurcation and chaos behavior especially the influence on bifurcation and chaos behavior of impact and rubbing fault rotor system...