Dynamic Modeling And Response Analysis Of Deep Groove Ball Bearing With Compound Fault On Raceway And Rolling Element

Rolling bearing is one of the key basic parts in rotating machine,which plays a decisive role in the operation of machinery,and determines the performance and reliability of the rotating machine.Rolling bearing is often operating under complex working conditions such as variable speed and variable load.Local faults are easy to occur on the surface of the rolling element or the raceway,which may be expanded to complex multi-point faults and even cause serious accidents.Therefore,the study of dynamic vibration characteristics of rolling bearings provides certain theoretical basis for health management,condition monitoring and fault diagnosis of bearings,and it has great significance for ensuring the safe operation and reducing economic losses.Considering the Hertz contact,time-varying displacement and other factors,the contact between the defect on rolling element surface and the raceway of the deep groove ball bearing is analyzed.The dynamic model of the deep groove ball bearing is established.The characteristics of contact force excitation and vibration response induced by composite defects between rolling element and raceway are investigated.The main researches are summarized as follows:(1)The excitation relationship of contact deformation-induced through local defects is investigated.The failure types and mechanism of rolling bearings are expounded.The complexity and uncertainty of the contact between surface defects and inner and outer raceways are considered.A simplified hypothesis is made for the shaft-bearing-pedestal system,and the relationship between time-varying displacement caused by defects and internal excitation such as Hertz contact force is obtained.(2)The dynamic model of deep groove ball bearing with local defects on surface of rolling element and raceways is constructed.A contact model between faulty rolling element and inner or outer raceway is introduced.The contact model between local defects of rolling element and inner or outer raceway is simplified,and the contact deformation and motion of rolling element crossing inner and outer raceway are analyzed.A 4-DOF dynamic model of bearing with composite faults(surface defects on the rolling element and the inner/outer race)is established by extending the single faults of the bearing into composite faults,and the model has been verified by experiments.The influence of contact deformation and time-varying displacement excitation on bearing vibration characteristics is investigated when the defective rolling element crossed the inner or outer raceway and the healthy rolling element entered the defective area on raceways.(3)The influence of different working conditions on vibration of defective bearings is investigated.The influences of different speeds,defect sizes and load conditions on the bearings are studied based on the proposed dynamic model,the excitation mechanism of local defects and the vibration of bearings are discussed under different conditions.The results show that the vibration signal of composite fault is the coupling of impact signals from single point fault on the rolling body and raceway,and the vibration amplitude of bearing would increase with the increase of speed,load and defect size.