Research On Failure Mechanism Of Aeroengine Rolling Bearings And Experimental Verification

Rolling bearings are very significant mechanical transmission components,which are widely used in mechanical field,such as in automobiles,aerospace,equipment manufacturing,industrial production equipment.In automobiles,the rolling bearings are very important mechanical components,which play an irreplaceable role in the performance of engines,gearboxes and shafting transmission.They are of great significance to the fault simulation analysis of gearboxes and bearings on engines,also can assist in fault diagnosis.In addition,aero-engine spindle bearings are particularly prone to failure,because aero-engine has high speed,bad operating conditions,those are high temperature,heavy load,oil pollution and so on.Therefore,simulation analysis of fault dynamic response of high-speed bearings is of great value for fault diagnosis and prediction of aero-engine spindle bearings.In this paper,a two-degree-of-freedom fault dynamic model for deep groove ball bearings with ordinary rotational speed and a fault dynamic model for angular contact ball bearings with high speed are presented.The fault dynamic response is obtained by solving the model based on the fourth-order Runge-Kutta method and Newton-Lafferson method.The relevant experiments have been conducted for the signals of fault bearings to validate the proposed dynamic model.Because bearings are loaded by multiple rolling elements in operation simultaneously,the coupling effect between the loaded rolling elements will occur,so it is necessary to consider the coupling effect of the fault displacement impulse excitation of the rolling element when constructing the fault dynamic model of deep groove ball bearings;in order to simulate the symmetrical characteristics of the dynamic response impulse characteristics of the fault,the subsection effect of the fault displacement excitation would be considered by introducing optimization coefficients a and b.Then an optimal fault dynamic model of deep groove ball bearings with two degrees of freedom for ordinary rotational speed is constructed.The Hertz contact force between a single rolling element and raceway and the dynamic velocity response along the Y direction are obtained by solving the model with the fourth order Runge-Kutta method.The results show that the impact response and symmetry are more obvious.Comparing the simulation results of the optimization model with the bearing experimental data of Case Western Reserve University,it is proved that the optimization model has better simulation performance than the traditional model.A dynamic model of spalling fault high-speed angular contact ball bearings is constructed based on the fault dynamic model of low-speed bearings,and building a dynamic model of burn fault high-speed angular contact ball bearings.The state equations of high-speed bearing rolling elements are solved by Newton-Lafferson method to obtain the spatial position parameters and stress state of the rolling elements,and the time-varying contact angle and contact stiffness between the rolling elements and rings.Then these time-varying high-speed effect parameters are coupled to the dynamic model of high-speed bearing with localized fault,and the fourth-order Runge-Kutta method is used to solve the model.Considering the danger of burned bearing experiment,only the dynamic model of high-speed bearing with peeling fault is validated and analyzed.The dynamic response data of high-speed bearing with peeling fault are collected by using a high-speed test platform of aeroengine spindle bearing.By comparing the dynamic response results of fault bearing at different rotational speeds and different fault sizes in time domain and frequency domain,it can be seen that the fault dynamic response obtained from the optimized model considering the high-speed effect of rolling element and experimental data are better matched,and has more reasonable amplitude.Therefore,it can prove that the proposed fault dynamic model of high-speed angular contact ball bearing has better dynamic response fitting performance for fault bearing than the traditional model.Therefore,in the dynamic analysis of deep groove ball bearings with local faults and high-speed angular contact ball bearings with local faults,the proposed optimization model can genetate more accurate simulation dynamic response,which can achieve better results than the traditional model,and can better assist bearing fault diagnosis and fault prediction.