Ductile Fracture Prediction of Arctic High Tensile Steel(EH36) Using Various Damage Evolution Functions

Abstract

Accidental loads such as ship collisions and groundings can cause catastrophic structural damage where large amount of structural fracture can occur. Two stress-associated parameters of stress triaxiality and Lode angle are known to be governing parameters on the ductile fracture. Recent research has reported that loading path or stress path is also one of the important parameters. The three-dimensional fracture strain surface for EH36 low temperature steel was developed based on a series of the tension/compression tests for the notched specimens subjected to the tension, shear, shear-tension, and compression (Choung el al. 2015a; 2015b; 2016). To account for the non-proportional stress effects even under the monotonic tensile testing, the linear and non-linear damage evolution models were newly presented with combination of the calibrated fracture strain surface. The material constants associated with the damage evolutions were identified from calibration with the experimental data. Validation of the damage-based fracture models was conducted by comparing predicted fracture strains with the results of the asymmetrically notched specimens and with the punch test results. The fracture model with the non-linear damage evolution predicts slightly more improved predictions than the linear damage-based fracture model.