The Research Of Crack Rolling Contact Fatigue In Deep Groove Ball Bearing

Rolling bearing has the advantages of small friction resistance,low power consumption,simple structure,easy to start and so on.Moreover,it is standardized and serialized production with good interchangeability,thus suitable for mass production and easy to maintain.As the advantages above,rolling bearing is widely used in various machinery.With the rapid development of science and technology,the more and more complex operating conditions and working environments of the rolling bearing demand advances in material,structure and performance.Therefore,it is very important to study the rolling contact fatigue failure of rolling bearing raceway to improve the anti-fatigue performance of rolling bearing.In this paper,rotating contact behaviors of deep groove ball bearing inner raceway with defects and cracks on the surface were studied using finite element simulation method.Both linear elastic material model and elastic-plastic model were simulated to clarify effects of shape,size and distribution of sub-surface defects as well as size and location of surface cracks on fatigue crack initiation and propagation of deep groove ball bearings.The simulation results revealed the rolling contact fatigue failure mechanism of the deep groove ball bearing raceway,and main research contents are as follows:(1)The contact behavior of deep groove ball bearing inner raceway was simulated,and the influence of load and the shape,size and position of sub-surface defects on the crack initiation and propagation was investigated.We found that the fatigue crack expansion of bearing raceway occurs mainly in the raceway position near the surface and sliding growth mode was the primary pattern of fatigue crack initiation and propagation,openning and tearing growth mode are the auxiliary pattern.The closer the distance between material defect and the raceway surface was,the greater the fatigue damage rate was.As for the major axis radius of defect,it had the same effcts on the fatigue damage rate with distance,but the major axis radius of defect caused totally reverse effects.It is also found that the fatigue damage rate increases gradually with the increase of radial load,radius of raceway curvature and surface friction force.(2)The influence of defect's distribution on fatigue damage of bearing raceway is studied.When the axial distance of defect is small,the propagation rate of defects is large,and fatigue failure is most likely to occur in a certain range which is around the Hertz contact center.Crack's propagation rate is small when the spacing of defects is large,and fatigue failure is most likely to occur at the defect under the positive center of the Hertz contact area.The smaller the radial distance of the defect is,the greater the propagation rate of the crack is,and the crack propagation is most likely to occur at the position of the defect which is closest to the surface.(3)The rotational contact behavior of the inner raceway of the deep groove ball bearing with surface crack is simulated,the effects of the inclination angle of the crack,the depth of crack and the inclination angle of the secondary crack on the crack propagation are studied.The results show that the smaller the inclination angle of the crack is and the shallower the depth is,the more the crack propagation rate is,the more serious the rolling contact fatigue damage is.In the surface and near surface of the raceway,pressure and friction together contribute to the growth of surface cracks,but in the deep area,it is mainly caused by pressure to promote the growth of the crack.The study also showed that the smaller the Angle of the secondary crack is,the shorter the expansion path of fatigue crack in the raceway is,and the faster the fatigue flaking of raceway is.And when the Angle of secondary crack is large,the crack will grow deep into the raceway and gradually away from the stress field,and eventually stop growing.