Experimental Investigation of Forming Limit Curve for AA5754-O

The Forming Limit Curve (FLC) is a line that is consisted of the major and minor strain pairs for different kinds of strain paths. It is widely adopted for the quantitative description of the sheet metal formability. In this paper, a stand-alone servo-motor apparatus associated with the high-accuracy measurement system was developed, based on which the FLC of AA5754-O with the thickness of 3.0mm was investigated. Firstly, the material properties of metal sheet were explored and the anisotropic coefficients in the constitutive law were calculated to describe the yield behaviour. Secondly, in order to increase the strain level of cruciform specimens, various simulations with different shapes of specimens were performed with AB AQUS/Explicit. Finally, the biaxial tensile tests with the optimized shape of cruciform specimens were performed under different loading ratio conditions. The experimental FLC of AA5754-O was obtained. The fracture zone of each specimen was occurred in the central region without premature arm fracture, which verified the feasibility of the cruciform specimen purposed.