# CONTEXT.md — Hydrotech Beam Structural Optimization

## Client
Hydrotech (internal test fixture)

## Objective
Minimize beam mass while meeting displacement and stress constraints. Single-objective: minimize mass, constrain displacement (≤ 10 mm) and stress (≤ 130 MPa).

## Key Parameters — Confirmed (Gen 002)

| Parameter | NX Expression | Current | Range | Units | DV? | Notes |
|-----------|--------------|---------|-------|-------|-----|-------|
| beam_half_core_thickness | `beam_half_core_thickness` | 20 | 10–40 | mm | Yes (DV1) | Core half-thickness |
| beam_face_thickness | `beam_face_thickness` | 20 | 10–40 | mm | Yes (DV2) | Face sheet thickness |
| holes_diameter | ❓ (Gap G14) | 300 | 150–450 | mm | Yes (DV3) | Lightening hole diameter |
| hole_count | `hole_count` | 10 | 5–15 | integer | Yes (DV4) | Number of lightening holes |
| beam_length | `beam_length` | 5,000 | Fixed | mm | No | ✅ Confirmed KBS |
| beam_half_height | `beam_half_height` | ❓ (Gap G12) | — | mm | No | Half I-beam height |
| beam_half_width | `beam_half_width` | ❓ (Gap G13) | — | mm | No | Half flange width |
| hole_span | `p6` | 4,000 | TBD | mm | Potential (G15) | Total span for hole distribution |

## Constraints
- Max tip displacement: ≤ 10 mm
- Max von Mises stress: ≤ ~130 MPa (steel, conservative — Gap G9)
- Mass tracked via NX expression **`p1`** ← CORRECTED from `p173` (Gen 002)

## Baseline Performance — Confirmed (Gen 002)

| Metric | Value | Source | Confidence |
|--------|-------|--------|------------|
| Mass | **11.33 kg** | NX expression `p1`, KBS session | ✅ High |
| Tip displacement | ❓ **NEEDS RE-VERIFICATION** (Gap G10) | Was 22 mm at old model state | ⚠️ Low |
| Max stress | ❓ **NEVER MEASURED** (Gap G11) | — | ❌ None |
| Material | **AISI Steel 1005** | KBS session | ✅ High |
| Density | **7.3 g/cm³** | KBS session | ✅ High |

> ⚠️ **Mass discrepancy resolved:** Intake reported ~974 kg (`p173`). KBS session confirmed 11.33 kg (`p1`). See `kb/dev/gen-002.md` for full analysis.

## Boundary Conditions — Confirmed (Gen 002)

| BC | Location | Value | Source |
|----|----------|-------|--------|
| Fixed support | Left side (full edge) | All DOF constrained | ✅ KBS session |
| Applied force | Right side (free end) | 10,000 kgf downward (−Y) | ✅ KBS session — "project requirement" |
| Configuration | Cantilever | Left fixed, right loaded | ✅ KBS session |

## Mesh — Confirmed (Gen 002)

| Property | Value | Source |
|----------|-------|--------|
| Element type | CQUAD4 (thin shell) | ✅ KBS session |
| Element size | 33.7 mm (67.4/2) | ✅ KBS session |
| Idealization | Promote body → mid-surface extraction | ✅ KBS session |

## Hole Geometry — Confirmed (Gen 002)

| Property | Value | Notes |
|----------|-------|-------|
| Span | 4,000 mm (expression `p6`) | Total distribution length |
| Start offset | 500 mm from beam start | Fixed requirement — not parametric |
| End offset | 500 mm from beam end | Fixed requirement — not parametric |
| Collision check | Required at DV extremes | 15 × 450 mm in 4,000 mm → overlap |

## Model Files
- NX Part: `Beam.prt`
- FEM: `Beam_fem1.fem`
- Idealized part: `Beam_fem1_i.prt`
- Simulation: `Beam_sim1.sim`
- Solver: NX Nastran SOL 101 (static structural)

## Future Expansion
- Material alternatives: Aluminum 6061, Stainless Steel ANSI 310 (per Antoine, KBS session)
- `p6` (hole span) as additional design variable (pending decision)
- Mesh refinement (Antoine: "Eventually we're going to be able to refine the element size")

## Decisions
- 2026-02-08: Project received from Antoine
- 2026-02-10: KBS sessions processed → Gen 002 KB update. Mass corrected, BCs confirmed.

## Status
Phase: Pre-optimization (baseline re-verification needed)
Generation: 002
Channel: #project-hydrotech-beam
Last KBS session: 2026-02-10T16:38:01