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WP07 WEDGE6 kernel evidence

WP07 implements the six-node, 18-DOF triangular-prism kernel authorized by the Terra High T1-R4 review. The implementation is intentionally limited to an elemental small-strain, homogeneous isotropic elastic route. It is technical evidence, not a public qualification or a complete WEDGE6 workflow.

Implemented contract

  • Shape functions, natural derivatives and isoparametric mapping follow qualification/0_2_7/wedge6_formulation_contract.json.
  • Physical gradients and the 3-D engineering-shear B matrix use (xx, yy, zz, xy, yz, xz) ordering.
  • TRI3_X_GAUSS2 is the six-point full-integration production rule.
  • DUFFY_GAUSS5_X_GAUSS4 is a 100-point independent reference rule used only for verification. Reduced or selective integration is not implemented.
  • Elemental strain/stress recovery is reported at production integration points; stress extrapolation is not implicit.

Geometry boundary

Before stiffness or recovery, WEDGE6 geometry is checked by the exact triangular-vertex reduction from T1-R3. At each triangular reference vertex, det(J)(t) is evaluated as a quadratic on [-1, 1], including both endpoints and every interior stationary point. The minimum is compared with a machine-epsilon-scaled determinant guard. Quadrature and interior samples are diagnostics only. Non-finite, coincident, inverted, degenerate or unresolved orientation cases fail closed; no node-order auto-repair exists.

The Terra adversarial prism, which can pass sparse integration samples while having an interior negative determinant, is recorded as EXPECTED_FAILURE_PASS in the WP07 evidence artifact.

Targeted V&V result

The declarative catalog is executed by scripts/run_wedge6_wp07.py through the V&V v2 runner. The committed evidence records source SHA, input and result digests, oracle/tolerance metadata, verdict, runtime and artifact class.

Check Result
shape identities and affine reproduction PASS
Jacobian certificate and nominal geometry PASS
Terra interior-inversion adversarial case EXPECTED_FAILURE_PASS
elastic stiffness symmetry PASS
free-element rank / rigid-body modes rank 12, modes 6
constant strain, tension, compression, shear PASS
bending-like finite energy PASS
distorted positive-Jacobian prism PASS
production/reference quadrature PASS
deterministic harness replay PASS

Maturity and deferred scope

The registry records COMB-WEDGE6-linear_static as technically supported and verified but EXPERIMENTAL in qualification state. The descriptor/preflight reports the route as EXPERIMENTAL_ROUTE; it does not create a public qualified claim. Gmsh import, face loads, user-level assembly/reactions, modal or dynamic routes, nonlinear materials, contact and external correlation remain deferred to later work packages.

No TET4, TET10, HEX8 or HEX20 formulation was modified. Full regression is not part of this WP07 targeted checkpoint.

Provenance

  • Implementation source SHA: 9c23706e952262ab8ee71d85c809e46d7abab8b7
  • State: qualification/0_2_7/wp07_state.json
  • Case catalog: qualification/0_2_7/vnv_v2/wp07_cases.json
  • Evidence: qualification/0_2_7/vnv_v2/wp07_evidence.json
  • Formulation contract: qualification/0_2_7/wedge6_formulation_contract.json
  • Kernel: src/solveur/elements/solid/wedge6.py