Research On Stress And Fatigue Performance Of GCr15 Bearing Inner Ring By Laser Shot Peening

As a key component of the harmonic reducer,the flexible bearing bears alternating cyclic loads during service,and the inner ring of the bearing is easy to fatigue failure,which greatly shortens the service life of the harmonic reducer.As a new type of surface strengthening technology,laser shot peening technology can induce high-amplitude compressive residual stress on the surface of the parts,which can effectively inhibit the initiation of fatigue cracks and slow the growth rate of fatigue cracks,thereby increasing the fatigue life of the parts.This paper takes GCr15 steel flexible bearing inner ring as the research object.The load distribution law of the bearing inner ring,the laser shot peening process and its influence on the surface residual stress,microhardness,wear resistance and contact fatigue life of the bearing inner ring were studied by finite element simulation and experimental analysis,and the life extension mechanism of the laser shot peening bearing inner ring was revealed.The main work contents were as follows:(1)The peak pressure of shock wave and its residual compressive stress induced by laser peening were summarized.Combining the yield strength of the bearing inner ring GCr15 bearing steel and the Hugoniot elastic limit,the shock wave pressure loading range and its corresponding laser energy threshold were optimized;Based on the related theories such as plastic deformation and fatigue damage of metal materials,and from the perspectives of the formation of residual compressive stress and the grain refinement of surface structure,the mechanism of laser shot peening-induced stress strengthening and grain structural strengthening to improve bearing fatigue life was discussed.(2)The finite element model of the flexible bearing was established with ABAQUS finite element software,the load distribution of the components during the assembly and rotation of the flexible bearing was studied.Then,based on the principle of laser shot peening,the analysis model of laser shot peening for the inner ring of the bearing was established,and the influence of different laser shot peening paths,shock wave pressure and shot peening times on the residual stress field of bearing inner ring was studied;The stress/strain results after laser shot peening were used as the prestress field,and the influence of the residual stress field on the stress field of the bearing inner ring at various stages was analyzed.The n Code fatigue software was used to predict the fatigue life of the bearing inner ring after laser shot peening,and the influence of laser parameters on the fatigue life was analyzed.(3)A laser shot peening test was carried out to study the influence of process parameters(laser energy,shot peening times,etc.)on the surface performance of the bearing inner ring,including residual stress field,microhardness and friction and wear properties,revealing the relationship between process parameters and surface properties.At the same time,the fatigue life test of the flexible bearing was carried out to analyze the influence of the surface properties on the fatigue life of the bearing inner ring after laser peening,and the fatigue life extension mechanism of the laser peening bearing inner ring was explained.