The Experimental And Simulation Study On Laser Shock Processing And Fatigue Life Of Gear Tooth Root

Gear,as one of the most commonly used key parts in mechanical equipment,usually made by high-strengh still,will be subjected to the alternating bending stress for a long time during the service period,so it is easy to break the tooth under fatigue.As a new strengthening technology,laser shock processing can make the strengthened surface form residual compressive stress layer,increase the dislocation density,refine the grain size,and effectively improve the fatigue performance of the tooth root part of the gear.Because there are many factors that affect the results of laser shock strengthening,it will cost a lot of human and financial resources to carry out the research by just using the experiment method.The finite element simulation method can avoid these problems very well.In this paper,the influence factors of laser impact strengthening,the strengthening of tooth root of gear and the effect of laser impact strengthening on the fatigue performances of three-point bending are studied by using of finite element simulation and experiment.It provides some guidance and basis for the actual laser impact strengthening process.In this paper,the basic research work is carried out for the laser shock strengthening finite element simulation,and the foundation analysis model is established.By comparing the simulation results with the results of the simulation under different conditions,the optimal parameters for the simulation and analysis are obtained.The single factor and orthogonal simulation experiments are carried out by using the basic modle,and the influence of each factor on the single point laser shock and multi-point laser shock strengthening results is obtained,and the causes of these results are analyzed.Comprehensive consideration is given to the selection of the optimal strengthening process.The real gear is modeled and the laser shock processing simulation of gear tooth root is carried out.The laser shock processing experiment of the base sample block and the tooth root of the gear was carried out,and the residual stress of the sample block,the surface of the gear tooth root and the depth direction of the layer of the sample block were measured by using the existing equipment.The residual stress distribution curve is drawn and compared with the residual stress extracted from the simulation model.The simulation and test results are analyzed to verify the accuracy of the simulation model.The tooth root fatigue test is represented by three point bending fatigue test.The constitutive model of the material is obtained by the mechanical properties test of materials,the three-point bending fatigue simulation is carried out by combining ABAQUS and FEsafe,and the true fatigue life of the parts is obtained by the three-point bending fatigue experiment.The effects of laser impact strengthening on the three-point bending fatigue properties of materials are obtained by theoretical,experimental and simulation methods.The results show that laser impact strengthening can increase the fatigue life of three-point bending by nearly three times.