A Non-Hertzian Contact Analysis For The Ball And Raceway Of A Transmission Bearing

Rolling bearing is one of the most widely used rotating parts in machinery industry, and also an important support unit of automotive transmission. It is easily to be damaged especially under harsh working conditions, such as high rotating speed, heavy load and poor lubrication. Excessive noise and premature breakdown of the automotive gearboxes are mainly caused by the failure of rolling-element bearings. The origins of failure in rolling bearings are mainly due to the contact of roller and raceway, resulting in such commonly known damages as pitting, spalling, crushing, peeling, scuffing. Therefore, the study of the real contact situation between roller and raceway is of great significance to the failure prediction of rolling bearings. Furthermore, the operating performance of bearing has a significant impact on the whole car’s performance.This paper determines the external load of rolling bearings for a type of twin countershaft transmission under the severest operating condition. The transmission bench test also shows supportive evidence and validates the present numerical studies.By taking into account such effects as radial and axial external load, clearance, cage-aligning, and the gravitational influence, a more accurate and comprehensive analysis is performed for load distribution over the balls of a deep groove ball bearing. According to the results, the most serious loaded ball is on the direction of radial external force. Moreover, the load distribution characteristics over balls under different external condition are analyzed.For the non-conforming contact between ball and the inner raceway in symmetrical section of circumferential plane, the two-dimensional cylindrical contact theory can be used for solving this case. Therefore, a two-dimensional finite element analysis(FEA) is validated against classical Hertz theory. A three-dimensional finite element model is further developed for the conformal contact between the ball and outer raceway. Elastic constitute model is used and only radial force is considered to obtain the conformal non-Hertzian influence.This work determines another non-Hertzian effect besides the geometrical conformal contact, namely the elasto-plastic constitute. Actually, when plastic deformation is brought to the bearing material, the purely elastic constitutive model can’t get the accurate results, and it’s also difficult to solve the three-dimensional contact of bearing with complex geometry in plastic zone using theoretical formula. Therefore, a non-Hertzian elasto-plastic contact analysis is performed, and compared with the pure-elastic FEA considering both the radial external load and axial external load. For a further study of the contact characteristics in the plastic zone, different overload conditions are introduced. A transient simulation between the ball and outer raceway is presented, and the results show that the stress distribution will tend to the rolling direction for the influence of frictional coefficient. The higher the frictional coefficient, the larger the offset angle.The non-Hertzian contact analysis of ball and outer raceway presented in this paper can achieve more accurate contact characteristics of bearing, which can effectively guide the surface treatment design of the bearing and the prediction of contact fatigue life. This study has some reference value to the design of the bearing, wear, lubrication and other research.