Two-parameter J-A estimation for weld centerline cracks of welded SE(T) specimen under tensile loading

Abstract

This work examines the J–A two-parameter characterization of elastic–plastic crack front fields for weld centerline cracks under tensile loading. Extensive finite element analyses (FEA) have been conducted to obtain solutions of the A-term for modified boundary layer (MBL) model and welded SE(T) fracture specimen. Solutions of the constraint parameter A were obtained for the material following the Ramberg-Osgood power law with variation of strain hardening exponent between 5 and 20. The crack geometries analyzed include shallow to deep cracks and remote tension loading levels cover from small-scale to large-scale yielding conditions for welded SE(T) specimen. The effects of material mismatch and weldment geometries on crack tip constraint were considered in the FEA based on an idealized tri-material weldment. A constraint parameter AMis, only caused by material mismatch, is defined and its parametric equation was obtained from MBL model. The total constraint in the tri-material weld structure for welded SE(T) specimen can be predicted by adding together AMis and A of homogeneous SE(T) specimen. Overall, Good agreements were achieved for welded SE(T) specimen with different crack sizes and weldment geometries from small-scale to large-scale yielding conditions. This methodology would be useful for performing constraint-based elastic-plastic fracture analyses of other welded test specimens.