https://mechcalc.net/blog/en/series/bs-7910-fracture-assessment/ Recent content in BS 7910 Fracture Assessment on MechCalc how-to Guide https://mechcalc.net/blog/og-default.png https://mechcalc.net/blog/og-default.png Hugo en Fri, 26 Jun 2026 10:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-annex-d-misalignment/ Fri, 26 Jun 2026 10:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-annex-d-misalignment/ When two plates or shells to be welded together are 'not aligned' (axial misalignment or angular distortion), the load path of a tensile load is forced to bend, adding a layer of local bending stress σs at the weld. BS 7910:2019 Annex D is a look-up handbook: it gives a formula for each of 10 standardized misalignment configurations (7 butt-joint types + 3 cruciform types), letting you compute σs directly from the geometry, or convert it to a stress magnification factor km to feed into the Annex M stress intensity factor and the Clause 7 fracture assessment. This article gives the physics, then a figure and algorithm for each type. https://mechcalc.net/blog/en/posts/bs7910-sstp10-fad-walkthrough/ Thu, 25 Jun 2026 14:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-sstp10-fad-walkthrough/ FITNET's second FAD worked example, SSTP10 — a welded stainless-steel wide plate with a through-thickness crack failing by ductile tearing. This post runs it in mechCalc's BS 7910 Clause 7 fracture assessment calculator, watches where the assessment point lands on the Failure Assessment Diagram, and cross-checks point by point against FITNET: the horizontal coordinate L_r matches almost digit-for-digit (0.511 vs 0.51), while the vertical coordinate K_r is cross-method (the source includes unquantified welding residual stress), so only L_r can be compared. https://mechcalc.net/blog/en/posts/bs7910-a533b-residual-kis-annexm/ Thu, 25 Jun 2026 10:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-a533b-residual-kis-annexm/ Across the four A533B welded-plate problems, the residual stress intensity factor K_I^S≈46 MPa·m^0.5 has always been entered directly into the FAD — but where does that number actually come from? This post uses the BS 7910 Annex M.4.2 calculator in mechCalc (finite-plate surface flaw, polynomial stress) to integrate the measured welding residual stress polynomial profile into the SIF at the deepest point of the crack, yielding 44.84 MPa·m^0.5 — only 2.5% off the 46 reported by FITNET — and shows how mechCalc reproduces this key intermediate quantity on its own. https://mechcalc.net/blog/en/posts/bs7910-a533b-hlht-fad-walkthrough/ Wed, 24 Jun 2026 13:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-a533b-hlht-fad-walkthrough/ The finale of the four problems on the A533B-1 welded plate: same temperature and regime as Problem 3 (HLAW) — −30 ℃, high load ratio — but with post-weld heat treatment (PWHT). This article works through HLHT to show the double dividend of PWHT — it both relaxes the residual field (K_I^S 46→5) and restores toughness by an order of magnitude (K_mat 62→321) — and how this drives K_r down from 3.94 to 0.60; plus a thought-provoking twist: even with smaller residuals and higher toughness, HLHT fails at a slightly lower load than HLAW. https://mechcalc.net/blog/en/posts/bs7910-a533b-hlaw-fad-walkthrough/ Wed, 24 Jun 2026 12:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-a533b-hlaw-fad-walkthrough/ Third of four problems on the welded A533B-1 plate: the HLAW specimen — as-welded, warmed to −30 ℃, with the load raised into the high load-ratio (large-plasticity) regime. We run it in mechCalc's BS 7910 Clause 7 fracture assessment calculator to see how the assessment calls plastic collapse once L_r=1.80 exceeds the cut-off value L_r,max, and why the relative weight of residual stress is diluted by plasticity at high L_r so that fracture toughness becomes the governing factor. https://mechcalc.net/blog/en/posts/bs7910-a533b-llht-fad-walkthrough/ Wed, 24 Jun 2026 11:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-a533b-llht-fad-walkthrough/ Second of four problems on the A533B-1 welded plate: same temperature as Problem 1 LLAW (−120 ℃), same region, same measured residual-stress profile — the only variable is that post-weld heat treatment (PWHT) was applied. Here we run LLHT in mechCalc's BS 7910 Clause 7 fracture-assessment calculator and watch a counter-intuitive result: its primary SIF is actually higher than LLAW, yet the assessment point lands lower, because the residual K_I^S drops from 46 to 5. https://mechcalc.net/blog/en/posts/bs7910-a533b-llaw-fad-walkthrough/ Wed, 24 Jun 2026 10:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-a533b-llaw-fad-walkthrough/ One of the four A533B-1 welded-plate problems: the LLAW specimen — as-welded, −120 ℃, low load ratio. It is the first of the four to fracture (1.27 MN). This post walks step by step through entering, computing, and reading the FAD in mechCalc's BS 7910 Clause 7 Fracture Assessment Calculator, to see exactly how the residual K_I^S of 46 MPa·m^0.5 pushes the assessment point to K_r=2.59, far beyond the Failure Assessment Line. https://mechcalc.net/blog/en/posts/bs7910-a533b-residual-stress-fad/ Tue, 23 Jun 2026 00:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-a533b-residual-stress-fad/ A set of large welded A533B-1 steel plates tested in four-point bending to fracture, built to answer a question engineers keep asking: where exactly does welding residual stress push the assessment point on the Failure Assessment Diagram (FAD)? We first lay out the background and the shared method, then break the four specimens (LLAW / LLHT / HLAW / HLHT) into four problems, give the FAD inputs and results for each, and re-run everything independently with mechCalc's BS 7910 Clause 7 fracture assessment, cross-checking point by point against the original literature.