Antoine
b88657b00c
Sources: 3 KBS capture sessions (20260210-132817, 20260210-161401, 20260210-163801)
Key changes:
- Mass corrected: 974 kg (p173) → 11.33 kg (p1) — KBS ground truth
- Beam length confirmed: 5,000 mm cantilever
- BCs confirmed: left fixed, right 10,000 kgf downward
- Material confirmed: AISI Steel 1005, density 7.3 g/cm³
- Mesh confirmed: CQUAD4 thin shell, 33.7 mm elements
- Hole geometry: span 4,000 mm (p6), offsets 500 mm fixed
- 3 gaps closed (G1, G2, G8), 6 new gaps identified (G10-G15)
- New expressions: beam_half_height, beam_half_width, beam_length, p6
Files: CONTEXT.md, kb/_index.md, kb/_history.md, kb/components/sandwich-beam.md,
kb/materials/steel-aisi.md, kb/fea/models/sol101-static.md, kb/dev/gen-002.md
4.7 KiB
4.7 KiB
Sandwich Beam
Type: Primary structural component Material: Steel (AISI 1005) — see steel-aisi.md Status: Confirmed from KBS session (Gen 002)
Description
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. Beam is extruded from an I-beam sketch profile.
Geometry — NX Expressions
| Parameter | NX Expression | Baseline Value | Units | DV? | Range | Notes |
|---|---|---|---|---|---|---|
| Beam half-height | beam_half_height |
❓ TBD (Gap G12) | mm | No (currently) | — | Half total I-beam height |
| Beam half-width | beam_half_width |
❓ TBD (Gap G13) | mm | No (currently) | — | Half flange width |
| Face thickness | beam_face_thickness |
20 | mm | Yes (DV2) | 10–40 | Flange thickness |
| Core half-thickness | beam_half_core_thickness |
20 | mm | Yes (DV1) | 10–40 | Half web height |
| Beam length | beam_length |
5,000 | mm | No | Fixed | ✅ Confirmed (KBS) |
| Hole count | hole_count |
10 | — | Yes (DV4) | 5–15 (integer) | ✅ Confirmed (KBS) |
| Hole diameter | ❓ (Gap G14) | 300 | mm | Yes (DV3) | 150–450 | ✅ Confirmed (KBS) |
| Hole span | p6 |
4,000 | mm | Potential (G15) | TBD | ✅ Confirmed (KBS) — total span for hole distribution |
| Hole start offset | (fixed) | 500 | mm | No | Fixed | Requirement — not parametric |
| Hole end offset | (fixed) | 500 | mm | No | Fixed | Requirement — not parametric |
Mass
| Parameter | NX Expression | Value | Units | Source |
|---|---|---|---|---|
| Mass (baseline) | p1 |
11.33 | kg | ✅ KBS session 20260210-163801 |
| Density | (material card) | 7.3 | g/cm³ | ✅ KBS session — Antoine stated directly |
⚠️ Previous value of ~974 kg (expression
p173) is superseded. See Gen 002 mass discrepancy resolution.
Construction Method
- Sketch: I-beam cross-section profile with 4 key expressions (
beam_half_height,beam_half_width,beam_face_thickness,beam_half_core_thickness) - Extrusion: Sketch extruded to
beam_length(5,000 mm) → solid body - Holes:
hole_countcircular holes of specified diameter, distributed overp6span (4,000 mm), centered in web, starting 500 mm from each end - Idealization: Promote body → mid-surface extraction (pair mid-surface function) → thin shell sheet bodies
Hole Geometry Constraints
- Span: Holes are distributed over 4,000 mm (expression
p6) - Fixed offsets: First hole center at ≥500 mm from beam start, last hole center at ≤4,500 mm from beam start
- Spacing: At baseline: 10 holes in 4,000 mm → ~444 mm center-to-center, 300 mm diameter → ~144 mm ligament
- Collision risk: At extremes (15 holes × 450 mm dia in 4,000 mm): spacing = 267 mm, ligament = −183 mm → HOLES OVERLAP → infeasible
- Feasibility formula:
ligament = (hole_span / (hole_count - 1)) - hole_diameter > 0- Must also check:
hole_diameter < web_height(hole fits in web vertically)
- Must also check:
Structural Behavior
From Technical Breakdown (Gen 001), confirmed by KBS session:
The beam is a cantilever (left side fixed, right side free with 10,000 kgf downward load). It is bending-dominated:
| Behavior | Governing Parameters | Notes |
|---|---|---|
| Bending stiffness (EI) | Face thickness, core thickness | Faces carry bending stress, core carries shear. Stiffness scales ~quadratically with distance from neutral axis |
| Mass | All four variables | Core and face add material; holes remove material from web |
| Stress concentrations | Hole diameter, hole spacing | Larger holes → higher SCF at edges. Closely spaced holes can interact |
| Shear capacity | Core thickness, hole count, diameter | Holes reduce shear-carrying area |
Design Variable Interactions
- Core × Face — classic sandwich interaction. Optimal stiffness balances core depth (lever arm) vs face material (bending resistance)
- Hole diameter × Hole count — both remove web material. Large + many could leave insufficient ligament width
- Face × Hole diameter — thicker faces reduce nominal stress, allowing larger holes
- Core × Hole diameter — core thickness determines web height, constrains max feasible hole diameter
History
- Gen 001 (2026-02-09): Initial documentation from intake + technical breakdown
- Gen 002 (2026-02-10): Updated with confirmed values from KBS sessions. Mass corrected from 974 kg → 11.33 kg. Beam length confirmed 5,000 mm. Hole parameters detailed. Expression names confirmed.