Modeling, testing and calibration of ductile crack formation in grade DH36 ship plates

The initiation of ductile fracture in grade DH36 shipbuilding steel was modeled using the Hosford-Coulomb fracture model. The hardening and ductile fracture characteristics of DH36 were assessed by performing experiments on notched tension, central hole tension, plane strain tension and shear specimens. Detailed finite element analysis of each experiment was performed to evaluate the evolution of local stress and strain fields. The loading paths to ductile fracture initiation were determined in terms of the stress triaxiality and Lode angle parameter histories extracted from finite element analyses with very fine solid element meshes. The Hosford-Coulomb fracture model parameters were identified using the extracted loading paths and adopting a linear damage accumulation law. It has been found that ductile fracture behavior of DH36 is dependent not only on the stress triaxiality but also the Lode angle.