Design of a cruciform biaxial tensile specimen for limit strain analysis by FEM

This paper is focused on a study of the sheet forming limit under complex strain loading paths. A cruciform biaxial tensile specimen with a chamfer on the arms and the central region is optimized by FEM simulation in order to realize the complex loading and the limit-strain states of sheet metals in the cruciform biaxial tensile test. An optimal shape of specimen is obtained under the following conditions: the stress distribution in the central region is uniform and large deformation is obtained easily during the stretching of the specimen. Different strain paths in the central region can be realized by adjusting the velocity boundary conditions.