| Rolling bearing is a key component widely used in mechanical equipment,and its running state directly affects the performance of related mechanical equipment.Due to the long-term cyclic load,the raceway contacts area material fatigue damage,resulting in material deterioration,weak bearing capacity,raceway surface plastic deformation;On the other hand,the rolling bearing will sometimes be impacted or overloaded,and the contact area between the rolling body and the raceway is prone to plastic deformation.In rolling bearings,because of the complex motion form between the rolling body and the raceway,if the rolling body and the raceway are in elastoplastic contact state for a long time,the fatigue life of the rolling bearing will be seriously affected.Therefore,based on the elastoplastic contact theory and continuous damage mechanics,this paper studied the influence of ball and raceway contact motion on the fatigue life of rolling bearings.The main research contents and conclusions are as follows:First of all,based on the theory of elastic-plastic contact and continuum damage mechanics and combined with the cyclic property of the bearing steel GCr15,coupling damage elastoplastic constitutive model is established,the return mapping algorithm on the basis of the fully implicit integration algorithm is adopted to establish the constitutive model for numerical implementation,and consistent expression of stiffness matrix is deduced.After that,Fortran programming language is used to complete the preparation of the constitutive model subroutine.Secondly,in the finite element software ABAQUS to establish the three-dimensional contact equivalent model of ball-raceway,combined with the user-defined material subroutine UMAT will build the elastoplastic damage constitutive model is embedded into the ball-raceway contact model,by loading different normal load after the stress and strain of raceway,validate the correctness of the established procedures.Then,the influence of the complex motion of the ball relative to the raceway on the stress and strain distribution of the raceway is studied when the contact friction coefficient between the ball and the raceway is in the range of 0 to 0.3 and the raceway material is in the state of elastoplastic behavior.It is concluded that the maximum Mises stress and the maximum Tresca stress appear on the subsurface when the friction coefficient is 0.With the increase of friction coefficient,the maximum Mises stress and the maximum Tresca stress gradually approach to the raceway surface and finally appear on the surface.With the increase of friction coefficient,spin has the greatest influence on raceway stress,followed by sliding and rolling.Therefore,in actual working conditions,when the friction coefficient is large,some moving components in the bearing should be reduced as far as possible.Finally,based on continuous damage mechanics,the fatigue damage process of raceway material was simulated in the finite element software ABAQUS and the fatigue life of bearing raceway was obtained.The finite element results are compared with those obtained by classical L-P theory.The results show that the elastoplastic damage model can reasonably predict the fatigue life of the bearing.For the raceway crack initiation life,the peak contact stress has a greater impact than the friction coefficient and the form of motion.When the friction coefficient is less than 0.05,the crack initiation life of rolling and sliding raceway is basically the same.When the contact stress continues to increase,the maximum Mises stress of the raceway exceeds the yield limit of the raceway material at the beginning,and plastic deformation occurs between the ball and the raceway,leading to low cycle fatigue failure of the raceway. |
