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6658de02f4
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feat(isogrid): FEA stress field → 2D heatmap → adaptive density feedback
Closes the optimization loop: OP2 results → density field refinement.
**extract_stress_field_2d.py (new)**
- Reads OP2 (3D solid or 2D shell elements) + BDF via pyNastran
- Projects element centroids to 2D sandbox coords using geometry transform
- Averages stress through thickness (for solid 3D meshes)
- Normalises by sigma_yield to [0..1]
- save/load helpers (NPZ) for trial persistence
**stress_feedback.py (new)**
- StressFeedbackField: converts 2D stress scatter → smooth density modifier
- Gaussian blur (configurable radius, default 40mm) prevents oscillations
- RBF interpolator (thin-plate spline) for fast pointwise evaluation
- evaluate(x, y) returns S_stress ∈ [0..1]
- from_field() and from_npz() constructors
**density_field.py (modified)**
- evaluate_density() now accepts optional stress_field= argument
- Adaptive formula: η = η₀ + α·I + β·E + γ·S_stress
- gamma_stress param controls feedback gain (0.0 = pure parametric)
- Fully backward compatible (no stress_field = original behaviour)
Usage:
field = extract_stress_field_2d(op2, bdf, geometry["transform"], sigma_yield=276.0)
feedback = StressFeedbackField.from_field(field, blur_radius_mm=40.0)
eta = evaluate_density(x, y, geometry, params, stress_field=feedback)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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2026-02-18 11:13:28 -05:00 |
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