BS 7910 Reference Stress (Annex P)

BS 7910:2019 Annex P — Net-section plastic collapse reference stress for 33 crack geometries

BS 7910 Annex P — Reference Stress (\sigma_{ref})

Based on BS 7910:2019+A1:2020 Annex P (net-section plastic collapse, normal bending restraint), this module routes by crack type to the appropriate reference-stress solution:

• 33 crack geometries: flat plates (P.4–P.6, incl. double-edge P.4.3 and extended embedded P.5.4), thin & thick cylinders — axial (P.8) and circumferential (P.9/P.10), spheres (P.11) and round bars / bolts (P.12).
• Boundary conditions: plate Eq. P.9 (normal / fixed-grip restraint) vs Eq. P.10 (negligible / pin-jointed restraint), and plane stress / plane strain for the double-edge limit load.
• Collapse mode: each result reports the BS 7910 Annex P.3 plastic collapse mode — local ligament vs net-section (global).
• Load ratio & collapse cut-off: L_r = \sigma_{ref}/\sigma_Y (Eq. 7.40) and L_{r,max} = (\sigma_Y + \sigma_U)/(2\sigma_Y), the FAD horizontal axis and plastic-collapse limit.
• Thick-wall limit-load solutions: pressure (P.8.6/8.7), membrane+bending (P.8.8) and the circumferential tension+global-bending equation system (P.10).

Accuracy: simplified assessment (Vereinfachte Nachrechnung) per BS 7910 Annex P, no built-in safety factors. For a full fracture assessment combine with the BS 7910 Fracture Assessment Engine.

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