Evaluation of fracture mechanics parameters for a range of weldment geometries with different mismatch ratios

• η factor has been evaluated in welded fracture geometries.
• η factor is relatively insensitive to N, weld width and stress state.
• η factor has a variation of ±20% due to mismatch ratio.
• The recommended solutions of ηLLD and ηCMOD has been examined for each fracture geometry.

The elastic–plastic fracture mechanics J-integral parameter and its analogous creep fracture mechanics parameter C∗, are widely employed to characterise the material’s fracture and crack growth behaviour over a range of temperatures and loading configurations. Experimentally the non-linear component of the J-integral and C∗ parameter are evaluated using the geometry dependent fracture mechanics parameter the η factor. For weldments, the η factor is dependent on the relative size and yield strength properties of the base (parent) and weld materials and their mismatch ratio. In this work, the η factor has been evaluated for six fracture geometries using non-linear finite element method for a power law hardening material, and the results have been compared with literature where available. The obtained results, which fall within the best upper/lower bounds, are tabulated for each geometry and the recommended η for a range of mismatch factors are given as a function of the normalised crack length.