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 + Introspection)
| Parameter |
NX Expression |
Current |
Range |
Units |
DV? |
Notes |
| beam_half_core_thickness |
beam_half_core_thickness |
25.162 |
10–40 |
mm |
Yes (DV1) |
Core half-thickness |
| beam_face_thickness |
beam_face_thickness |
21.504 |
10–40 |
mm |
Yes (DV2) |
Face sheet thickness |
| holes_diameter |
holes_diameter |
300 |
150–450 |
mm |
Yes (DV3) |
✅ G14 closed |
| hole_count |
hole_count (→ Pattern_p7) |
10 |
5–15 |
integer |
Yes (DV4) |
Pattern parameter link |
| beam_length |
beam_lenght ⚠️ |
5,000 |
Fixed |
mm |
No |
Typo in NX — no 'h' |
| beam_half_height |
beam_half_height |
250 |
— |
mm |
No |
✅ G12 closed |
| beam_half_width |
beam_half_width |
150 |
— |
mm |
No |
✅ G13 closed |
| hole_span |
p6 (→ Pattern_p9) |
4,000 |
TBD |
mm |
Potential (G15) |
Total span for hole distribution |
Constraints
- Max tip displacement: ≤ 20 mm (relaxed from 10mm — CEO approved 2026-02-13, dummy case)
- Max von Mises stress: ≤ ~130 MPa (steel, conservative — Gap G9)
- Mass tracked via NX expression
p173 (body_property147.mass [kg])
Baseline Performance — Confirmed (Introspection)
| Metric |
Value |
Source |
Confidence |
| Mass |
1,133.01 kg |
NX expression p173, CEO correction + binary introspection |
✅ High |
| Tip displacement |
19.56 mm (node 5161, Tz = −19.51 mm) |
OP2 parse via pyNastran, SOL 101 baseline run 2026-02-10 |
✅ High |
| Max von Mises stress |
117.48 MPa |
OP2 parse via pyNastran, CQUAD4 shell stress |
✅ High |
| Material |
AISI Steel 1005 |
physicalmateriallibrary.xml |
✅ High |
| Density |
7.3 g/cm³ |
KBS session |
✅ High |
⚠️ Mass history: Intake reported ~974 kg → CEO corrected to 1,133.01 kg (p173). Discrepancy with intake likely due to different parameter state. Binary introspection confirms p173: body_property147.mass in kg.
NX Expression Map — Full Introspection
Design Variables
| Expression |
Value |
Unit |
Type |
beam_face_thickness |
21.504404775742785 |
mm |
Number — continuous |
beam_half_core_thickness |
25.162078968746705 |
mm |
Number — continuous |
holes_diameter |
300 |
mm |
Number — continuous |
hole_count |
10 |
— |
Integer (via Pattern_p7) |
Fixed Geometry Parameters
| Expression |
Value |
Unit |
beam_half_height |
250 |
mm |
beam_half_width |
150 |
mm |
beam_lenght |
5,000 |
mm |
Hole Pattern Expressions
| Expression |
Value/Formula |
Notes |
p6 |
4,000 mm |
Hole span — potential DV |
Pattern_p7 |
→ hole_count |
Count link |
Pattern_p8 |
444.444 mm |
Computed spacing (span / (count-1)) |
Pattern_p9 |
→ p6 |
Span link |
Pattern_p10 |
(linked) |
|
Pattern_p11 |
10 mm |
|
Pattern_p12 |
0 mm |
|
Mass Properties (Measure Body)
| Expression |
Formula |
Unit |
p170 |
surface_area |
mm² |
p171 |
volume |
mm³ |
p172 |
center_of_mass |
mm (point) |
p173 |
mass |
kg |
p174 |
weight |
N |
p175 |
density |
kg/mm³ |
Other
| Expression |
Value |
Notes |
p4 |
→ beam_lenght |
Alias |
p119 |
4,000 mm |
|
p132 |
444.444 mm |
Computed |
p134 |
4,000 mm |
|
p135 |
4,000 mm |
|
p139 |
10 mm |
|
p141 |
0 mm |
|
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 |
| Computed spacing |
444.444 mm (4000 / 9) |
At baseline (10 holes) |
| 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)
- NX Version: DesigncenterNX 2512 (Siemens rebranded NX → "DesigncenterNX")
- Install path:
C:\Program Files\Siemens\DesigncenterNX2512 (on dalidou)
First Results (2026-02-11)
| Metric |
Value |
Notes |
| Displacement |
17.93 mm |
At baseline-ish DVs |
| Von Mises stress |
111.9 MPa |
At baseline-ish DVs |
| Solve time |
~12 s/trial |
On dalidou (Windows) |
| Mass extraction |
Via p173 expression |
Journal writes _temp_mass.txt |
Both constraints violated at baseline (disp > 10mm). Optimization will need to find stiffer/heavier designs or relaxed constraints.
Future Expansion
- Material alternatives: Aluminum 6061, Stainless Steel ANSI 310 (per Antoine, KBS session)
p6 (hole span) as additional design variable (pending decision G15)- 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. BCs confirmed.
- 2026-02-10: Binary introspection — all expression names/values confirmed. Mass = 1,133.01 kg.
- 2026-02-11: NX version fixed (DesigncenterNX 2512), path resolution bugs fixed, iteration architecture finalized (backup/restore in-place), history DB added. First real solve results.
Status
Phase: DOE re-run — mass bug fixed, constraint relaxed, ready for clean DOE
Generation: 004
Channel: #project-hydrotech-beam
Last update: 2026-02-13
Solver Pipeline Status
- ✅ NX journal solve working (DesigncenterNX 2512)
- ✅ Mass extraction fixed — commit
580ed65 (MeasureManager after geometry rebuild, no more stale p173)
- ✅ Displacement & stress extraction via pyNastran OP2 parsing
- ✅ Iteration archival (params, results, OP2, F06)
- ✅ History DB (SQLite + CSV, append-only, survives --clean)
- ✅ Geometric pre-checks (hole overlap, web clearance)
- ✅ Displacement constraint relaxed: 10mm → 20mm (DEC-HB-012)
- 🔄 Pull fix on dalidou → test single trial → re-run full DOE
DOE Phase 1 Results (pre-fix, 51 trials)
- 39/51 solved, 12 geo-infeasible (hole overlap)
- 0 fully feasible at 10mm constraint (min displacement ~19.6mm)
- Mass = NaN on all trials — extraction bug (now fixed)
- Stress constraint met by several trials
- With 20mm relaxation, many trials should now be feasible
Development Workflow
- Git only for development (git push/pull between server and dalidou)
- Syncthing paused to avoid conflicts during active development
- Resume Syncthing for production/delivery phases
