Dynamics Modeling And Vibration Response Analysis Of Rolling Element Bearing System With Local Defect Of Displacement Excitation

2Rolling bearing is one of the most important parts in rotating machinery.With the development of science and technology,the requirement of bearings for rotating machinery is higher and higher.In order to improve the accuracy and stability of mechanical equipment and prevent catastrophic accidents caused by the rolling bearings sudden failure,it is very important of bearing condition monitoring and fault diagnosis in advance.So it has a great significance for bearing condition and maintenance.The main content of this thesis are as following:(1)The dynamics modeling of rolling element bearing with local defect of displacement excitation is established.The crack is regarded as the rolling bearing local defect in this model and the local defect surface profile is simplified to rectangular.In order to analyze the vibration response of rolling bearing with local defect,the 2-DOF dynamic model of displacement excitation in a rolling element bearing system with the local defect is established,which is based on hertz contact theory.(2)The effects of elasto-hydrodynamic lubrication in rolling bearing of the vibration response is studied.The elasto-hydrodynamic lubrication is introduced in the model based on contact mechanics.The fourth-order Runge-Kutta method is used to solve the dynamic model equations of the model and the dynamic response of displacement excitation with local defects bearing under elasto-hydrodynamic lubrication is obtained.The vibration signal is obtained by test rig,the correctness of the model is validated by comparing the analog signal and test signal.The results show that the lubricating fluid can restrain the vibration of rolling bearing.(3)The effect of rolling element sliding and bearing husing to the vibration response of rolling bearing is studied.The rolling element slipping which is expressed by the angular displacement and the bearing housing which is expressed by the contact stiff are added to the 2-DOF model established above.The fourth-order Runge-Kutta method is used to acquire the vibration response.The analysis of the vibration signal shows that the rolling element slipping and the bearing housing stiff can increase the amplitude of the vibration signal and accelerate the damage of the bearing.(4)The effect from different working conditions for the vibration response of rolling bearing is studied.By studying the vibration signal under different conditions,such as the various sizes of the defects,rolling speeds and external loads,the vibration signal with the same state under different conditions are compared.The results show that with increase of the size of the defect,the speed of the rolling bearing and the external load are larger,the amplitude of the vibration response would be increased.