Comparative study on ductile fracture prediction of high-tensile strength marine structural steels

Accidental events such as collision, grounding, and explosion in marine structures can cause plastic deformation and structural damage. Various fracture models based on different mechanical concepts have been proposed to predict damage extents involving ductile fracture. In this paper, some fracture models were evaluated: Maximum shear stress, Cockcroft-Latham, Johnson-Cook, Modified Mohr-Coulomb, Lou-Huh, and Hosford-Coulomb models. The model parameters were identified for two shipbuilding steel grades: AH36 and DH36. A hybrid experimental-numerical approach was adopted. The parameters of six fracture models were identified using an optimisation algorithm based on the extracted loading paths from the numerical simulations and adopting a linear damage accumulation law. The calibrated fracture models are presented in stress triaxiality and Lode angle parameter space as a 3D fracture locus, and under plain stress condition as a function of the stress triaxiality as a 2D fracture locus. The predictive capabilities and flexibility of the evaluated fracture models were discussed.