Statics Analysis And Fatigue Life Study Of Integral Cold Expansion Forming Drive Axle Housing Considering Residual Stress

Automobile drive axle housing is the main force component of the automobile,the load is mainly the alternating load on the spring seat of the body,vertical force,tangential force and lateral force of the ground wheel.Compared with other processing processes,welding triangle plate in the manufacturing process of integral cold expansion forming bridge housing produces larger residual stress.Under the coupling action of residual stress and mechanical stress caused by external load,the bridge housing is seriously fractured due to insufficient fatigue life.It is of great significance to carry out statics analysis and predict fatigue life of axle housing considering residual stress.In this paper,the driving axle housing of a 13-ton heavy truck is taken as the research object.In order to verify the accuracy of welding simulation,the welding triangle plate process of the axle housing is simulated and analyzed and the corresponding verification test is carried out.Considering the large size of the axle housing,it is beyond the test range of the test-bed.A flat plate with triangular openings and round holes was used instead of the axle housing.Firstly,SYSWELD was used to simulate and analyze the welding process of triangular plate,and the distribution of welding residual stress was obtained.Secondly,the triangular plate was welded to the plate under the actual working conditions,and the residual stress of the plate surface was measured by X-ray diffraction method.Comparing the measured and simulated values of welding residual stress and weld pool size,the results show that the error is within the allowed range,which verifies the accuracy of welding simulation results.The three-dimensional simplified model of the drive axle housing was imported into SYSWELD,and the thermal coupling finite element simulation was carried out on the welded triangle plate and the heat treatment process of the axle housing,and the distribution cloud diagram of the residual stress of the axle housing after heat treatment was obtained.In order to study the influence of residual stress on the mechanical properties of the axle housing,the static analysis of the drive axle housing under typical working conditions was carried out,and the stress and deformation cloud maps of the axle housing under various working conditions were obtained.The results show that the full load condition of the axle housing is dangerous condition considering the residual stress.By comparing the stress and deformation of bridge shell with or without residual stress,it can be concluded that residual stress will increase the stress and deformation of bridge shell.Secondly,the fatigue life of the drive axle housing was calculated by ANSYS n Code Design Life to simulate the bench test conditions,and the life cloud of the axle housing under two conditions was obtained.The comparison showed that the residual stress would reduce the fatigue life of the axle housing.The fatigue life of the axle housing considering the residual stress is 550 thousand times,which is less than the specified value in the vertical bending fatigue test of the drive axle.To sum up,residual stress will adversely affect the mechanical properties of the axle housing,and it is necessary to optimize the manufacturing process of the axle housing.Finally,the influence of tempering temperature,holding time and heating rate on the residual stress of the bridge housing was studied.The results show that increasing the tempering temperature,heating rate and prolonging holding time in a certain range can significantly improve the effect of eliminating the welding residual stress of the bridge housing.By optimizing the heat treatment process parameters,the results show that the residual stress of the optimized axle housing decreases by 61.17% compared with that before optimization.The statics and fatigue life of the rear axle housing treated by the optimized process under full load condition are analyzed.The results show that the strength and stiffness of the axle housing meet the design requirements,and the fatigue life is increased by nearly 1.1 times compared with that before optimization,which meets the design standards.