Keystone v13: linear elastic fracture mechanics (stress-intensity factors)#665
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…tors) Add a from-scratch LEFM chapter to the Keystone FEA studio: extract the crack-tip stress-intensity factor K_I on the existing Q4/Q8 isoparametric machinery, without ever resolving the 1/√r singularity. - fracture.ts: graded cracked-plate mesher (tip-clustered, crack on the y=0 symmetry plane), compact assemble/PCG solve, and K_I via the domain J-integral and the interaction (M-) integral with unit-K Williams auxiliary fields; displacement-correlation cross-check; Feddersen/Tada handbook factors and a live a/W sweep. - fracturepresets.ts: center / single-edge / double-edge crack scenarios plus a material toughness library (steel, Al, Ti, PMMA, alumina, glass). - FractureStudio.tsx: fifth self-contained studio tab — singular tip field with opening crack faces and the J-integral ring, the K(a/W) sweep vs handbook, the full SIF read-out, and a K_Ic fracture verdict (safety factor, critical stress and flaw size, plastic-zone check). - 8 new live closed-form benchmarks (badge 73 -> 81, all green): center Y vs Feddersen, J = K_I^2/E*, Griffith limit, J path independence, SENT/DENT Y vs Tada, mode-I purity, and the DCM cross-check. Verified end-to-end in headless Chromium: all five tabs render, the tip blooms the singularity, K_I matches the handbook to -0.2%, and the gate is green. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DTEUgLrMy1nRS7ced4a3D9
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Adds a from-scratch Linear Elastic Fracture Mechanics chapter to the Keystone structural-FEA studio — the crown-jewel FEM topic it was missing. Everything below builds on the existing Q4/Q8 isoparametric machinery; scope is confined to
projects/keystone-fea-b3k9/.What it does
At a sharp crack the elastic stress is singular (σ ~ K/√(2πr)), so peak stress is meaningless and the stress-intensity factor K (units Pa·√m) governs failure instead. This chapter meshes a cracked plate by symmetry (with a graded tip mesh) and extracts K_I two ways that never touch the infinity:
Three canonical configurations ship (center crack, single-edge/SENT, double-edge/DENT), a live a/W sweep traces the computed geometry factor onto the closed-form handbook curve, and K_I is turned into an engineering fracture verdict against a material's K_Ic (safety factor, critical stress, critical flaw size, plastic-zone check) across steel, aluminium, titanium, PMMA, ceramic and glass.
New / changed files
src/engine/fracture.ts— graded cracked-plate mesher, assemble/PCG solve, domain J-integral, interaction integral with Williams aux fields, displacement-correlation cross-check, Feddersen/Tada handbook factors, a/W sweep.src/engine/fracturepresets.ts— crack scenarios + material toughness library.src/ui/FractureStudio.tsx— fifth self-contained studio tab (singular tip field, opening crack faces, J-integral ring, K(a/W) sweep, SIF read-out, fracture verdict).validate.ts/components.tsx— 8 new live benchmarks wired into the Verified badge.App.tsx/state.ts/App.css— the new tab.JOURNAL.md/project.json— v13 log, backlog, and metadata.Validation — badge 73 → 81, all green
Verified end-to-end in headless Chromium: all five tabs render, the tip blooms the 1/√r singularity, K_I = 102.6 MPa√m matching the handbook to −0.2%, the a/W sweep points land on the curve, the steel verdict flips to FRACTURES, and
node scripts/verify-project.mjs keystone-fea-b3k9(conformance + lint + build) is green.🤖 Generated with Claude Code
https://claude.ai/code/session_01DTEUgLrMy1nRS7ced4a3D9
Generated by Claude Code