A new continuous tensile-compressive testing device with friction-counteracting and anti-buckling supporting mechanism for large strain

The forming process of sheet metal is a complicated procedure relating to tensile and compressive plastic deformation. The in-plane tensile-compressive test is a main way to understand the plastic behavior under the complicated loading paths. In this paper, a new device is developed to realize in-plane tensile-compressive tests in order to study the plastic behavior during tension and compression of sheet metal. The newly-developed device has the advantages of high efficiency and low cost. It can support a reliable continuous, large-strain tensile-compressive test for more materials with higher strength based on any common universal testing machine. A set of friction-counteracting supporting mechanism including T-shaped supporting plates, Teflon sheets and upper/lower fixtures is designed to prevent buckling deformation of sheet metal during compression. Moreover, the tensile-compressive tests of DP780 steel are conducted by using the new device to obtain the tensile-compressive stress-strain curve reflecting the Bauschinger behavior. The constitutive model of DP780 steel is established and the optimal model parameters are achieved for the simulation analysis. As a result, the simulated tensile-compressive curves match the experimental curves very well. The newly-developed device is favorable to accurately describe the plastic behavior under the complicated loading paths during forming and contribute to precise simulation analysis.