# Knowledge Base — Hydrotech Beam

**Project:** Hydrotech Beam Structural Optimization
**Generation:** 003
**Last updated:** 2026-02-11

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## Overview

I-beam optimization for a test fixture. Steel (AISI 1005) cantilever beam with lightening holes in the web. Goal: minimize mass from **1,133.01 kg** baseline while meeting displacement (≤ 10 mm) and stress (≤ 130 MPa) constraints.

**Key confirmed parameters (Gen 003):**
- Beam length: 5,000 mm (`beam_lenght` ⚠️ typo in NX), cantilever — left fixed, right loaded
- Load: 10,000 kgf downward at free end
- Baseline mass: **1,133.01 kg** (expression `p173: body_property147.mass`)
- DV baselines: face=21.504mm, core=25.162mm, holes_dia=300mm, hole_count=10
- Material: AISI Steel 1005 (density 7.3 g/cm³)
- Mesh: CQUAD4 thin shell, 33.7 mm element size
- **Solver:** DesigncenterNX 2512 (NX Nastran SOL 101)
- **First results (2026-02-11):** Displacement=17.93mm, Stress=111.9MPa, Solve time ~12s/trial

## Components

| Component | File | Status |
|-----------|------|--------|
| Sandwich Beam | [sandwich-beam.md](components/sandwich-beam.md) | ✅ Updated Gen 002 |

## Materials

| Material | File | Status |
|----------|------|--------|
| Steel AISI 1005 | [steel-aisi.md](materials/steel-aisi.md) | ✅ Updated Gen 002 |

## FEA

| Model | File | Status |
|-------|------|--------|
| Static Analysis (SOL 101) | [fea/models/sol101-static.md](fea/models/sol101-static.md) | ✅ Updated Gen 003 — Solver running, first results obtained |

## Generations

| Gen | Date | Summary |
|-----|------|---------|
| 001 | 2026-02-09 | Initial KB from intake + technical breakdown |
| 002 | 2026-02-10 | KBS session processing — confirmed geometry, BCs, mesh, material, mass correction |
| **003** | **2026-02-11** | **First real results! NX version fix (DesigncenterNX 2512), path resolution, backup/restore architecture, history DB, mass extraction via journal** |

## Gap Tracker

### ✅ CLOSED

| # | Item | Resolution | Closed In |
|---|------|------------|-----------|
| G1 | Beam length and support conditions | 5,000 mm cantilever (left fixed, right free) | Gen 002 |
| G2 | Loading definition | 10,000 kgf point load, downward (−Y), at free end | Gen 002 |
| G8 | Mesh type and density | CQUAD4 thin shell, 33.7 mm element size (67.4/2) | Gen 002 |

### 🟡 PARTIALLY RESOLVED

| # | Item | Known | Remaining |
|---|------|-------|-----------|
| G5 | Hole geometric feasibility | Span = 4,000 mm, offsets = 500 mm fixed. Baseline: 10 holes × 300 mm → ~144 mm ligament (OK) | Need collision check at DV extremes. 15 × 450 mm WILL overlap. Need feasibility constraint. |
| G9 | Stress allowable basis | AISI 1005 yield ~285 MPa. 130 MPa → SF ≈ 2.2 | Need confirmation that 130 MPa limit still applies to updated model. |

### ❓ STILL OPEN

| # | Item | Why It Matters | Priority |
|---|------|---------------|----------|
| G7 | NX parametric rebuild reliability | Untested across full DV range — need corner-case testing | Medium |
| G15 | `p6` (hole_span) as potential DV | Antoine suggested it could be optimized. Decision needed. | Medium |

### ✅ CLOSED (Gen 003 — 2026-02-11)

| # | Item | Resolution | Closed In |
|---|------|------------|-----------|
| G3 | Displacement measurement location | Max Tz at free end, extracted via pyNastran OP2 | Gen 003 |
| G4 | Stress constraint scope | Whole model max von Mises (CQUAD4 shell) | Gen 003 |
| G6 | Result sensors in Beam_sim1.sim | Using pyNastran OP2 parsing, not NX sensors | Gen 003 |
| G10 | Baseline displacement | 17.93 mm at baseline-ish DVs | Gen 003 |
| G11 | Baseline stress | 111.9 MPa at baseline-ish DVs | Gen 003 |
| G12 | `beam_half_height` value | 250 mm — confirmed via binary introspection | Gen 002+ |
| G13 | `beam_half_width` value | 150 mm — confirmed via binary introspection | Gen 002+ |
| G14 | Hole diameter expression name | `holes_diameter` — confirmed via binary introspection | Gen 002+ |

## Open Tasks

1. **Run full 51-trial DOE** — solver pipeline operational, execute Phase 1
2. **Corner-case testing** — verify NX rebuild at DV extremes (G7)
3. **Decision on `p6` as DV** — consult Manager/CEO (G15)
4. **Phase 1 → Phase 2 gate review** — after DOE completes, assess feasibility landscape