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FESADev/references/quad_02_notes.md
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# quad_02 Reference Notes
## Purpose
`quad_02` is the first stored Abaqus `TYPE=S4` reference pair intended for the Phase 1 MITC4 rebaseline path.
The original Abaqus input remains preserved as provenance:
- `quad_02.inp`
- `quad_02_displacements.csv`
The Phase 1 parser-compatible derivative input is:
- `quad_02_phase1.inp`
## Provenance
- Source solver: Abaqus/CAE Learning Edition 2024, as recorded in `quad_02.inp`.
- Original job name: `quad_02`.
- Source model name: `Model-1`.
- Unit system: self-consistent source units. FESA does not enforce or convert units.
## Compatibility
`quad_02.inp` uses `TYPE=S4`, which is the Phase 1 target mapped to FESA `MITC4`.
The original file also contains Abaqus/CAE features outside the current Phase 1 parser subset:
- `*Part`
- `*Assembly`
- `*Instance`
- `*Density`
- output and restart request keywords
These features remain unsupported in Phase 1 unless `docs/ABAQUS_INPUT_SUBSET.md` and ADRs are explicitly updated. Tests must continue to reject the original file as unsupported provenance.
## Normalized Input
`quad_02_phase1.inp` is a derivative input created for Phase 1 parser and later solver regression work.
It preserves:
- 121 node ids and coordinates.
- 100 `TYPE=S4` quadrilateral elements and connectivity.
- Elastic material values `E = 7.0e10`, `nu = 0.3`.
- Shell thickness `1.0`.
- Fixed boundary nodes from the original assembly-level boundary set.
- Concentrated load at node `2`, DOF `3`, magnitude `-100000.0`.
It removes:
- Abaqus/CAE `Part/Assembly/Instance` scaffolding.
- `*Density`, because density is not used by Phase 1 linear static analysis.
- restart/output requests.
- step increment parameters and static time data not needed by the Phase 1 parser subset.
## Result Mapping
`quad_02_displacements.csv` is an Abaqus-exported nodal displacement table with 121 rows.
Required columns:
- `Node Label`
- `U-U1`
- `U-U2`
- `U-U3`
- `UR-UR1`
- `UR-UR2`
- `UR-UR3`
It maps to FESA field output:
```text
/results/steps/Step-1/frames/0/fieldOutputs/U
```
with component order:
```text
UX, UY, UZ, RX, RY, RZ
```
## Initial Tolerance
The active automated displacement regression uses:
```text
abs_tol = 1.0e-12
rel_tol = 1.0e-5
reference_scale = 1.0
```
Do not tune tolerances or drilling stiffness to make this single case pass.
## Automated Regression Status
`quad_02_phase1.inp` and `quad_02_displacements.csv` are wired into the Phase 1 test suite as the first stored Abaqus displacement regression.
The regression compares FESA `U` against the stored Abaqus CSV by node id and uses the tolerance above.
## Current Limitations
- `RF` has no paired Abaqus reaction CSV yet; verify `RF` by full-vector equilibrium until a `quad_02_reactions.csv` artifact is provided.
- This is currently the only passing stored Abaqus reference regression. The PRD target still requires at least three stored reference models: one single-element case, one simple multi-element plate/shell case, and one curved shell benchmark.