Calibration of GTN model for fracture analysis of steel plates with holes

Net section fracture of steel plates with holes is a common failure mode of bolted connections in steel constructions. This research aimed to investigate the applicability of the Gurson-Tvergaard-Needleman (GTN) model for analyzing net section fracture of steel plates with holes. The GTN model was first calibrated for Q355D steel through tensile tests on notched round bar specimens and complementary finite element (FE) analysis. Then, tensile tests were conducted on Q355D steel plate specimens with holes. Four different shapes (circular, elliptic, hexagonal and rhombic) of holes were designed to account for potential variations of the stress concentration level. All the plate specimens failed due to net section fracture during the tensile tests. Load-displacement curves and fracture displacements were obtained by the tests for these specimens. FE analysis was carried out to simulate the tensile tests on the plate specimens and the calibrated GTN model was employed to address their net section fracture. The net section fracture captured by the GTN model agreed very well with the test results. The agreement validates the applicability of the GTN model for net section fracture analysis of steel plates with holes. Finally, FE models of plate specimens with circular and rhombic holes were established with meshes of different sizes for mesh sensitivity analysis. It was found that the net section fracture analysis of the plate specimen with circular holes is less sensitive to the mesh size of the FE model due to its lower stress concentration level.