Numerical Simulation And Experimental Study On Formability Of Aluminum Alloy Sheet

With the rapid development of the society,the amount of the car will be more and more,with the increase of the car ownership,it brings some series of social problems such as security,pollution and resources.The automotive industry is facing severe challenges now,and the focus of the automobile industry is moving towards a lighter direction.Aluminum alloy has excellent mechanical properties,good formability and abundant resources.It is the most ideal material to realize vehicle lightweight.The research shows that the weight of the car can be reduced by 2.25kg and the weight loss effect is up to 125%per use of 1kg aluminum,and the car's own weight per weight reduction is 10%,the fuel consumption can be reduced by 6%,and the emissions of carbon monoxide and carbon dioxide can be reduced by 4%.If subjected to the same impact,aluminum can absorb more than 50%of impact energy and higher safety performance than steel.The proportion of iron and steel on automobile consumption is decreasing year by year,and the proportion of aluminum materials is increasing year by year.In spite of this,the stamping process of aluminum alloy used in automobile production is lack of systematic and in-depth research,which hinders the application of aluminum alloy on the automobile.Therefore,the numerical simulation and experimental research of aluminum alloy formability have important guiding significance for the practical application of aluminum alloy in automobile production.Based on the theory of elastic plastic and instability of sheet metal,based on the nonlinear finite element software DYNAFORM of sheet forming,the stamping process of aluminum alloy sheet is simulated on the 6016 aluminum alloy,and the factors affecting the forming quality of the aluminum alloy sheet are analyzed.First,the finite element model of the forming limit of aluminum alloy sheet is established and simulated.The simulation results are compared with the experimental results,and the influence of the constitutive equation,the yield criterion and the friction coefficient on the forming limit of the aluminum alloy sheet is analyzed.Secondly,based on the finite element simulation of the automobile beam,the influence of the blank holder force,the stamping speed,the drawing bar parameters and the arrangement mode on the forming quality of the aluminum alloy sheet is studied.The results of the study show that:(1)Hollomon,Power and Voce constitutive equations can predict the forming limit of aluminum alloy sheet.Compared with Power and Hollomon,the Voce constitutive equation can predict the forming limit of the aluminum alloy sheet more accurately.(2)Both the Barlat89 yield criterion and the Hill48 yield criterion can predict the forming limit of the aluminum alloy sheet,and the Barlat89 yield criterion can predict the forming limit of the aluminum alloy sheet more accurately than that of the Hill48.(3)The size of the friction coefficient has a certain influence on the forming limit of the aluminum alloy sheet,and the forming limit gradually increases with the increase of the friction coefficient,and the effect of FLD on the double pull area is larger than that in the tension compression region.(4)Adjusting the size of the blank holder force can effectively control the forming quality of the parts,the edge force is large,the flow of the material to the die is difficult,and the wrinkling area of the parts can be relieved.While the pressure side force is small,the flow of the material to the die is easy,and the fracture area of the parts can be improved.But simply relying on the size of the blank holder force can not improve the forming quality of the complex parts of the parts.(5)Different stamping speed and different strain rate during sheet forming affect the quality of sheet metal forming.The larger the stamping speed,the maximum thinning rate of the parts decreases and the decreasing trend becomes smaller and smaller.When the stamping speed increases to 4000mm/s,the maximum thinning rate of the parts will no longer decrease but gradually increase.(6)The radius of the rounded angle,the radius of the concave die and the distance between the bars are inversely proportional to the maximum thinning rate of the parts.That is,the maximum thinning rate of the parts decreases with the increase of the radius or the distance between the bars;the height of the drawing bar is proportional to the maximum thinning rate of the parts,that is,the maximum thinning rate of the parts increases with the height of the parts.(7)The arrangement of different drawing bars has a significant influence on the forming quality of the parts.Therefore,it is necessary to arrange drawbead reasonably in order to get ideal simulation results.