Dynamic Modeling And Vibration Analyzing Of Ball Bearing With Multi-event Excitation

Rolling bearings are the basic and key parts of rotating machinery and are widely used in many industries and fields.The existence of local defects on the surface of the bearing elements will cause the deterioration of the bearing performance and eventually lead to the failure of the bearing.The research for the vibration characteristics of the fault bearing can clarify the nonlinear contact mechanism between the bearing elements,and reveal the internal excitation mechanism induced by itself,which is of great practical significance for ensuring the healthy and safe operation of the equipment.In this thesis,the ball bearing as an example,based on the description and characterization of the whole cycle of multi-event excitation situation,a dynamic analysis model of ball bearing with defect on the inner ring surface is established,the vibration response characteristics of the rolling bearing caused by the defect from the perspective of internal excitation are analyzed,the mechanism of nonlinear vibration due to the defect is revealed.The main contents of this thesis are as following:(1)A description model of the whole cycle multi-event excitation is proposed.In view of the problem of the full representation of the contact relationship and the motion process between the rollers and the whole raceways,motion relationships and contact changes of rolling element are considered,the moving process of rolling element in a whole cycle is detailed,based on multi-event model,the interaction between bearing components in non defective area is described,an analysis model of the whole cycle multi-event excitation is put forward.(2)The mechanism of the periodic impact force and the nonlinear Hertz elastic contact force are clarified.The interaction of incentive mechanism of excitation force induced by the inner raceway surface local defect and load position relationship are analyzed,the excitation of time varying displacements due to the defect and the bearing varying compliance vibrations is summarized,the corresponding analytic functions of the periodic impact force and the nonlinear Hertz elastic contact force are constructed,the coupling relationship of excitation force and displacement due to the defect is discussed.(3)A dynamic analysis model of rolling bearings with the local defect on the inner ring surface is established.The influence of the periodic impact force and nonlinear Hertz contact force are considering.Based on the whole cycle of multi-event excitation,a 2 degree of freedom dynamic model of rolling ball bearing with local defect on the inner surface is established,and the validity and feasibility of the model are verified by fault bearing test.(4)The vibration responses of the defect bearing with different defect sizes and different working conditions are investigated.On the vibration responses of the bearings with and without defect are compared,the vibration mechanism of the nonlinear excitation of the bearing surface with the local defect is revealed,the defect sizes and shaft speeds and the external loads effect on the vibration response of the bearing are analyzed,In a certain range of the bearing vibration parameter changes with the defect sizes and shaft speeds and the external loads are studied.The results show that the vibration of the bearings can be aggravated by high speed,and heavy load and large defect size.