Study On Mechanism Of Fatigue Crack Propagation In A Tapered Roller Bearing Inner Ring

Rolling contact fatigue is one of the main failure modes of bearings.The fatigue and damage of bearing raceway is usually caused by the initiation and propagation of crack,and the extension of the crack can lead to the fracture of bearing ring.So,the study on crack propagation law of bearings in the process of serving is a premise for correct assessment of bearing residual fatigue life.Tapered roller bearings are the key components of advanced machinery such as aircrafts,ships,high-speed railways and superior automobiles,the fatigue failure of which will directly influence the service performance and service life of important equipment.Based on the basic theory of energy release rate and crack propagation dissipation,combined with the numerical simulation analysis method,the propagation mechanism for surface fatigue crack of tapered roller bearing raceway is studied and the energy change rule in the process of crack propagation is revealed.The main research content is as follows:(1)The initial crack location in the raceway surface is determined according to the surface stress condition of bearing raceway.On this basis,the numerical model of crack propagation for a tapered roller bearing inner ring with the fatigue crack in the raceway surface is established through extended finite element method(XFEM),and the reliability of the numerical model is verified.(2)Through numerical simulation,the critical load change rules of fatigue crack propagation in the raceway surface of a tapered roller bearing inner ring and the change rules of fatigue crack shape,fatigue crack propagation path and fatigue crack propagation energy are studied in linear loading.(3)Through numerical simulation,the influence of initial crack size and crack depth on fatigue crack propagation energy dissipation and energy release rate in the surface of a tapered roller bearing inner ring raceway is studied under cyclic load.(4)Through numerical simulation,the stress filed distribution regularity of crack tip for the fatigue crack in the raceway surface of a tapered roller bearing inner ring is studied.And the growth mode and propagation rate change rule of fatigue crack is studied and the fatigue crack propagation life is evaluated.The research in this paper has a certain scientific value and practical significance for deep understanding on surface fatigue crack propagation mechanism and establishing the crack propagation life evaluation method and fatigue damage safety design method of tapered roller bearing raceway.