Impact Excitation Modeling And Dynamic Response Analysis Of Rolling Bearing With Local Defects

Rolling element bearings are widely used in aeroengines,gas turbines and other rotating machinery.With the development of mechanical equipment in the direction of high speed and precision,the probability of rolling element bearing failure is becoming higher and higher.Local defects of rolling element bearings,such as spalls,pitting and wear,are the most common forms of bearing faults.Dynamic modeling and feature analysis of rolling element bearing with local defects can provide theoretical support for predicting and identifying bearing faults.The dynamic modeling of multi-event impact excitation for bearing raceway local defects was carried out,and the dynamic characteristics of defective ball bearing-rigid rotor system were studied by means of nonlinear vibration theory.The research work in this thesis was mainly carried out as follows:(1)A two-degree-of-freedom dynamic model of the healthy ball bearing-rigid rotor system was firstly established.The Hertz contact stiffness of ball bearings was calculated,the4 th order Runge-Kutta method was used to solve the differential equation of the system,and the dynamic response was obtained.The VC resonance of the system was studied,and the effect of system parameters on the resonance characteristics was discussed.(2)The dynamic modeling of multi-event excitation for bearing local defect was carried out.The ball passing through the defect zone was divided into the entry event and the exit event,where the change of clearance in the defect zone and the collision force between the ball and the defect edge were considered respectively,and the expression of the defect force under the multi-event excitation of local defect was established.The local fault model was imported into the healthy bearing system for solving,and the simulation signals were analyzed and verified in time domain and frequency domain.In addition,the local defect model of bearings established in this thesis was compared with the existing geometric model,focusing on the acceleration response and resonance characteristics of the two models,and the comparison results proved the advantages of the proposed model.(3)The influence of defect parameters on the dynamic response of the system was discussed,the acceleration response and resonance curve of the system under different defect size and defect location angles were calculated,and the influence law of defect parameters on the dynamic response of the system was then summarized.In addition,the single local defect of the bearing raceway was generalized to multiple local defects.The calculation results showed that the multiple point defects and the compound defects had similar dynamic behavior compared to the single point defect.