Determination of sheet metal flow behavior by inverse method with global optimization

The accurate flow curve is necessary for the forming process simulation. However, the stress-strain data under large strain after necking cannot be accurately obtained by the uniaxial tensile test directly. In this study, an inverse calibration method with computer-aided global optimization was proposed to identify precisely the stress-strain relationship after necking and determine the complete flow curve of the sheet metal material via experiment and simulation. The ability of several hardening models to fit the flow data was evaluated and modified. The fitting accuracy of flow data was greatly improved by the modified hardening functions.