Assemblies leaving a discontinuity at the root
Welded machine elements

The presence of a flat discontinuity at the root of a weld bead under load should, strictly speaking, give rise to a verification of the stability of this natural defect by means of fracture mechanics, involving the stress intensity factorsK_I, K_II, K_III at this location. As knowledge of these quantities is relatively complicated, in practice, the stability of the bead under load can be reduced to the assumption that the ductile state has been reached, given that :

• the modest thickness of the beads results in low tri-axiality of root stresses;

• the ductility of the regions adjacent to the root (ZF, ZAT, MB) is verified by QMOS tests.

Under these conditions, stability...