Optimization Of 6061 Aluminum Alloy Wheel Hub Structure Based On Service Performance And Forging Process

As the lightweighting of vehicles advances continuously,the application of aluminum alloy wheels is becoming more widespread.How to further achieve lightweighting on the base of application of “aluminium substituted steel” is a key issue of the current vehicle lightweighting field.In this paper,the 6061 aluminum alloy wheel of commercial vehicle was taken as the research object.The weak area of the wheel hub and the material deformation law of the area were found out through theoretical analysis.And the changes of microstructure and mechanical properties of the weak area were further understood by the designed equivalent test.Then the structure optimization of the wheel hub was taken basing on the result to achieve the target of lightweighting.The equivalent stress distribution and deformation of the wheel hub in dynamic bending fatigue test and dynamic radial fatigue test were simulated by finite element method.It is found that the equivalent stress and deformation of the wheel hub in dynamic radial fatigue test,which are 156.37 MPa and 0.47 mm,are larger.And the fatigue crack defects are likely to occur at the wheel hub vent,which is a weak area of the hub structure.According to the actual production requirements and the structural characteristics of the wheel hub,a two-step forging process was developed.The material flow,equivalent stress and equivalent strain in different deformation stages during the forming process were analyzed by Deform-3D finite element software.The three-direction stress state and the equivalent strain value of the weak area were obtained through the point tracking.According to the equivalent strain of weak area,which was 1.18,the unidirectional compression equivalent test was designed to analyzed the microstructure and mechanical properties of core region of the sample which had the same equivalent strain and similar stress state as the weak region.It is found that the yield strength and tensile strength of the material in weak region are increased by 77.1 MPa and 61.6 MPa,respectively;and the microstructures are significantly refined.According to changes of mechanical properties in weak areas during material deformation,aiming at the weight reduction under safely use conditions,the radius of the ventilating hole in the weak area,the thickness of the wheel rim and the thickness of the flange were selected as design variables.The maximum equivalent stress and the deformation in loading direction under dynamic radial load were selected as state variables;and the sensitivity data in response surface optimization method was combined to design the range of domain of definition.On this basis,the structure optimization of the wheel hub is taken to achieve the secondary lightweighting;and the weight of the wheel hub is reduced by 8.3%.Moreover,the structure of the weak area has been enhanced,which improves the using security of the wheel hub.