Material Parameters in the GTN Model for Ductile Fracture Simulation of G20Mn5QT Cast Steels

Abstract

Material parameters in the Gurson, Tvergaard and Needleman (GTN) model were calibrated for G20Mn5QT cast steels based on tests of tension coupons and smooth notched tensile specimens, and complementary FEA. The mesh sensitivity of the calibrated GTN model was discussed regarding the efficiency of the FEA. As the mesh size decreases to 0.15 mm or finer, the prediction of the ductile fracture by the calibrated GTN model tends to converge. Four single-edge notched plate specimens of G20Mn5QT cast steels were tested under uniaxial tension, and the entire ductile fracture processes of the specimens were obtained. The ductile fracture of a double-hole plate specimen and the single-edge notched plate specimens were then simulated using the calibrated GTN model. The accuracy of the calibrated GTN model was verified by comparing the numerical simulation with the test results. Also validated was that the GTN model is applicable to not only the ductile fracture prediction but also the simulation of the stable fracture propagation.