53 lines
2.5 KiB
Markdown
53 lines
2.5 KiB
Markdown
# Sandwich Beam
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**Type:** Primary structural component
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**Material:** Steel (AISI) — see [steel-aisi.md](../materials/steel-aisi.md)
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**Status:** Baseline documented, optimization pending
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---
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## Description
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Sandwich I-beam serving as primary load-bearing member in a test fixture assembly. Cross-section features a core layer flanked by face sheets on top and bottom flanges. Web contains a pattern of lightening holes (circular cutouts) to reduce mass.
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## Specifications
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| Parameter | Value | Units | Source |
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|-----------|-------|-------|--------|
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| Mass (baseline) | ~974 | kg | NX expression `p173` |
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| Tip displacement (baseline) | ~22 | mm | SOL 101 result |
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| Half-core thickness | 20 (baseline) | mm | DV range: 10–40 |
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| Face thickness | 20 (baseline) | mm | DV range: 10–40 |
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| Hole diameter | 300 (baseline) | mm | DV range: 150–450 |
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| Hole count | 10 (baseline) | — | DV range: 5–15 (integer) |
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| Beam length | ❓ TBD | mm | Gap G1 |
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| Support conditions | ❓ TBD | — | Gap G1 |
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## Structural Behavior
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*From Technical Breakdown (Gen 001):*
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The beam is **bending-dominated**:
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| Behavior | Governing Parameters | Notes |
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|----------|---------------------|-------|
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| Bending stiffness (EI) | Face thickness, core thickness | Faces carry bending stress, core carries shear. Stiffness scales ~quadratically with distance from neutral axis |
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| Mass | All four variables | Core and face add material; holes remove material from web |
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| Stress concentrations | Hole diameter, hole spacing | Larger holes → higher SCF at edges. Closely spaced holes can interact |
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| Shear capacity | Core thickness, hole count, diameter | Holes reduce shear-carrying area |
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## Design Variable Interactions
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1. **Core × Face** — classic sandwich interaction. Optimal stiffness balances core depth (lever arm) vs face material (bending resistance)
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2. **Hole diameter × Hole count** — both remove web material. Large + many could leave insufficient ligament width
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3. **Face × Hole diameter** — thicker faces reduce nominal stress, allowing larger holes
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4. **Core × Hole diameter** — core thickness determines web height, constrains max feasible hole diameter
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## Key Risk
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> ⚠️ Baseline FAILS displacement constraint (22 mm vs 10 mm target). Optimizer must increase stiffness by >50% while reducing mass. Feasible region may be tight.
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## History
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- **Gen 001** (2026-02-09): Initial documentation from intake + technical breakdown
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