Evolution And Spalling Of Localized Defect On Outer Raceway In Rolling Bearing Based On Finite Element Method

The rolling bearing is one of the main accurate parts of the rotating machine.The quality of bearing often determines the operability and reliability of the rotating mechanism in terms of its tolerances and dimensions.Localized defects often arise on the bearing raceway surfaces and balls due to the peculiar operation condition of the bearing such as high speeds and cyclic loads.The abnormal vibrations induced by the defect would affect the operation of the bearing and even cause damage of the rotating machine.Therefore,it is necessary to develop a dynamic model of the bearing with localized defect to investigate the responses of the system(outer race,balls,inner race,and cage)about defect evolution.It will provide a theoretical guide for diagnosing the malfunctions of the rotating machine.The research contents of this dissertation are as follows:(1)The 3-D FEM model of ball bearing ER-16 K with localized defect on outer raceway is developed.The materials of bearing components were determined,and the model was meshed.The boundary conditions such as contacts and forces are set for all components.Besides,the mathematical simulation module of the calculation system was configured.The FEM model was solved by using the transient structural module in Ansys workbench software.(2)An experiment was designed to verify the 3-D FEM model.The four testing bearings with different defect widths of 0.6 mm,1.2 mm,1.8 mm and 2.4 mm are used to verify the 3-D FEM model.It is shown that the simulation results fit the experimental results very well,and the 3-D FEM model can be used to analyze the vibration of bearing with localized defect.(3)The reason of the defect evolution was investigated by using 3-D FEM model.The stresses in the rolling elements were analyzed for different defect sizes.The reason for the propagation of the defect exactly along the direction of the rolling element moving was explained.The results show that the forces arise when the width of the defect changes.(4)The influence of the defect width on stress was investigated.The critical defect zone was identified in the defect evolution of bearing.The acceleration signal in the frequencydomain was investigated to detect the regularity of the effect of the defect width via FFT.