Calibration and Validation of GISSMO Damage Model for A 780-MPa Third Generation Advanced High Strength Steel 2020-01-0198
To accurately evaluate vehicle crash performance in the early design stages, a reliable fracture model is needed in crash simulations to predict fracture initiation and propagation. In this paper, a generalized incremental stress state dependent damage model (GISSMO) in LS-DYNA® was calibrated and validated for a 780-MPa third generation advanced high strength steels (AHSS), namely 780 XG3TM steel with a superior combination of high strength and excellent ductility. The fracture locus of the 780 XG3TM steel was experimentally characterized under various stress states including uniaxial tension, shear, plane strain and equi-biaxial stretch conditions. A process to calibrate the parameters in the GISSMO model was developed and successfully applied to the 780 XG3TM steel using the fracture test data for these stress states. The calibrated GISSMO fracture card for 780 XG3TM steel was then validated in simulations of wedge-bend tests, two notched tensile tests and axial crash tests of octagonal, 12-sided and 16-sided components. The predicted fracture locations, displacement at fracture and force-displacement curves agreed well with the test results. The study also demonstrates that 780 XG3TM steel, when combined with the 12 and 16-sided advanced section designs, significantly improves axial crash energy absorption efficiency with minimal fracture and offers a great opportunity for weight reduction.
Guofei Chen, Lu Huang, Todd M. Link, Tau Tyan, Krishnakanth Aekbote
United States Steel Corporation, Ford Motor Company