Numerical analysis on the effect of thickness on biaxial tension limits0

Forming limit curve is the plot between major and minor strain of a critical element during sheet metal forming. This curve provides the indication on how particular metal in a particular deformation mode can form safely. This knowledge further provides the input to design the tools which can form the safe product. As this method only follows the two principal strains it is mostly applicable to plane stress components. To accommodate complex deformation paths, researcher devised the biaxial machine which is designed specifically to provide biaxial stress components using multiple and varying loading condition. In this paper the cruciform shape specimen which has 4 arms can be pulled in positive displacement to provide tension in the material. With changing the displacement or rate on individual axis multiple deformation paths can be created. In this paper the limits of material in a biaxial tension was investigated with varying the thickness of a specimen. The conventional route to create the equi-biaxial tension is hemispherical dome test which is also investigated for different thickness. It was found that the thickness has negligible influence on biaxial results but does changes the strains in arm. It was also found that due to pressure effect, the limit in hemispherical dome test is higher than in biaxial test.