Annex M

The first step of a fracture assessment is to compute the stress intensity factor $K_I$ at the crack tip. This guide explains what $K_I$ is and how BS 7910 Annex M computes it — from the general master formula and its correction factors to the common semi-elliptical surface-crack solution and the weld-toe correction. It feeds the vertical axis $K_r$ of the Failure Assessment Diagram (FAD), and together with Annex P (reference stress) for the horizontal axis $L_r$ completes the Clause 7 fracture assessment . ...

In the FAD assessment of the [[bs7910-a533b-residual-stress-fad|four A533B welded-plate problems]], the residual stress intensity factor for the as-welded case, $K_I^S \approx 46\ \mathrm{MPa\cdot m^{0.5}}$, has always been entered directly: FITNET obtained it by integrating the measured residual stress profile, and we simply fed that ready-made number into the vertical coordinate $K_r$. A natural follow-up question: how does that 46 actually emerge from a residual stress curve, and can mechCalc compute it on its own? ...