Fracture mechanics — LEFM

Critical crack size + FAD screening

Stress-intensity factor K = Y·σ·√(π·a). Critical a where K = K_IC. Failure-Assessment-Diagram screening at the (Kr, Lr) point.

Inputs

Fracture toughness K_ICMPa·√m

Applied stress σMPa

Geometry factor Y—

1.12 surface flaw, 1.00 through-thickness centre crack, ~0.73 buried disc.

Crack depth amm

Through-wall crack · 2c · edge crack

LEFM K_I = Y·σ·√(π·a) — Y(edge crack) = 1.12 · K_I 42.11 MPa√m.

FAD — Failure Assessment Diagram (API 579 Annex 9B / BS 7910 Level 2)

Kr=0.526 · Lr=0.857 · Lr_max=1.25 → SAFE

K at current a42.11MPa·√m

K_r = K / K_IC0.526

Critical crack a*18.04mm

L_r ≈ σ/Sy (Sy=350 placeholder)0.857

FAD verdictNEAR-EDGE

For full FAD per API 579 Annex 9B, supply σ_ref via :code:`fad_assessment_lefm` agent tool. Default Sy here is a screening placeholder.

Download all inputs + calculations + outputs as a single PDF.