Sprint Contract: MITC4 Material Stiffness Extraction

Objective

Move MITC4 material matrix, covariant-to-local transform, integration scaffolding, drilling stabilization, stiffness assembly, and internal force helpers into the documented Element and Material module boundaries.

Required Reading

/AGENTS.md
/PROGRESS.md
/PLAN.md
/docs/README.md
/docs/HARNESS_ENGINEERING.md
/docs/ARCHITECTURE.md
/docs/ADR.md
/docs/NUMERICAL_CONVENTIONS.md
/docs/MITC4_FORMULATION.md
/docs/VERIFICATION_PLAN.md
/phases/1-structure-alignment-refactor/step0-architecture-map.md
/phases/1-structure-alignment-refactor/step6.md

Scope

Extract plane-stress MITC4 material matrix helpers and material diagnostics.
Extract 2 x 2 x 2 integration data, stiffness accumulation, local/global transform, drilling stabilization, MITC4ElementKernel, and internal force helpers.
Keep drilling_stiffness_scale = 1.0e-3 and reference-diagonal policy unchanged.
Keep Element responsible for MITC4 element kernel behavior; keep reusable material-law helpers under Material if separated.

Allowed Files

include/fesa/fesa.hpp
include/fesa/Element/
src/Element/
include/fesa/Material/
src/Material/
include/fesa/Math/
tests/
CMakeLists.txt
phases/1-structure-alignment-refactor/index.json
PLAN.md
PROGRESS.md

Explicit Non-Goals

Do not change MITC4 stiffness formulas, drilling policy, integration order, or patch-test tolerances.
Do not add stress/resultant output.
Do not add reduced integration, S4R, hourglass control, nonlinear tangent stiffness, or pressure loads.
Do not change assembly behavior beyond include dependency repair.

Tests To Write First

Add or update include/link tests for MITC4 stiffness/material module headers.
Preserve stiffness symmetry, rigid body, drilling sensitivity, internal force, patch, and locking-sensitivity tests as characterization tests.

Reference Artifacts

None.

Acceptance Commands

python scripts/validate_workspace.py

Evaluator Checklist

MITC4 material and stiffness code no longer lives in the umbrella header as implementation.
Drilling policy matches docs/MITC4_FORMULATION.md.
Element patch and locking-sensitivity tests still pass.
No unsupported Abaqus behavior or result output is added.
Public facade includes remain compatible.

Handoff Requirements

Update this step status in phases/1-structure-alignment-refactor/index.json.
Record moved MITC4 material/stiffness files and any remaining MITC4 implementation still left in fesa.hpp.

Do Not

Do not optimize or parallelize element stiffness in this relocation step.
Do not use reference displacement mismatch to retune formulation parameters.

2.7 KiB Raw Blame History