Numerical simulation of sheet metal forming of an Al-Mg alloy incorporating plane strain properties in the yield criterion

In this work, numerical simulation of AA5083-O aluminum alloy sheets is carried out using Yld2000-2d yield criterion to predict thinning and variation of load with displacement in sheet metal forming. It has been found that the accuracy of predictions in numerical simulation depends on the coefficients and the stress exponent used in the yield criterion. Hydraulic bulge tests with circular and elliptical die cavities are performed to characterize the material in equi-biaxial and plane strain conditions. An improved stress exponent is determined by incorporating the material properties obtained in plane strain in the existing criterion. The improved stress exponent is validated by using it in the numerical simulations of cylindrical cup deep drawing and stretch forming at room temperature. The same exponent is also used in the numerical simulations carried out for the case of experiments conducted at 250 degrees C. The predicted thinning and load-displacement variations from the numerical simulations are validated with the experimental measurements. A considerable improvement in the results predicted using the improved stress exponent is observed at both the temperatures.