Abstract
Considerable work has been done on the modelling of fracture and necking for accidents in the maritime and offshore industry, but very little has been done to find the crack orientation during this failure. Such information will be required in future analyses which use the eXtended Finite Element Method (XFEM), rather than the element deletion approach which is typically used. It also offers a more realistic portrayal of the extents of damage, which will be useful in assessments of salvageability and residual strength analysis in maritime structures. This paper reviews the current state of the art on the direction of necking and fracture relative to the main in-plane loading axes. It was found that necking and fracture can both evolve under different angles relative to the first principal stress, depending on the ratio of inplane strains, material anisotropy, and other effects. Traditional analysis has given an easy relationship between necking orientation and strain ratio for negative second principal strains. Anisotropy is found to have a very important role for the necking angle for strain ratios (ε2/ε1) greater than 0.5. Fracture theory predicts a fracture angle perpendicular to the first principal stress for states of stress between uniaxial tension and equi-biaxial tension, but it predicts in-plane slant fracture for strain ratios less than −0.5.