131 lines
2.9 KiB
Markdown
131 lines
2.9 KiB
Markdown
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# bracket_pareto_3obj
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Three-objective Pareto optimization: minimize mass, minimize stress, maximize stiffness
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**Generated**: 2025-12-06 14:43
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**Protocol**: Multi-Objective NSGA-II
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**Trials**: 100
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---
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## 1. Engineering Problem
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Three-objective Pareto optimization: minimize mass, minimize stress, maximize stiffness
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---
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## 2. Mathematical Formulation
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### Design Variables
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| Parameter | Bounds | Units | Description |
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|-----------|--------|-------|-------------|
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| `support_angle` | [20, 70] | degrees | Angle of support arm relative to base |
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| `tip_thickness` | [30, 60] | mm | Thickness at bracket tip where load is applied |
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### Objectives
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| Objective | Goal | Extractor | Weight |
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|-----------|------|-----------|--------|
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| mass | minimize | `extract_mass_from_bdf` | 1.0 |
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| stress | minimize | `extract_solid_stress` | 1.0 |
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| stiffness | maximize | `extract_displacement` | 1.0 |
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### Constraints
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| Constraint | Type | Threshold | Units |
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|------------|------|-----------|-------|
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| stress_limit | less_than | 300 | MPa |
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---
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## 3. Optimization Algorithm
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- **Protocol**: protocol_11_multi
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- **Sampler**: NSGAIISampler
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- **Trials**: 100
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- **Neural Acceleration**: Disabled
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---
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## 4. Simulation Pipeline
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```
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Design Variables → NX Expression Update → Nastran Solve → Result Extraction → Objective Evaluation
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```
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---
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## 5. Result Extraction Methods
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| Result | Extractor | Source |
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|--------|-----------|--------|
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| mass | `extract_mass_from_bdf` | OP2/DAT |
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| stress | `extract_solid_stress` | OP2/DAT |
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| stiffness | `extract_displacement` | OP2/DAT |
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---
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## 6. Study File Structure
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```
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bracket_pareto_3obj/
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├── 1_setup/
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│ ├── model/
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│ │ ├── Bracket.prt
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│ │ ├── Bracket_sim1.sim
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│ │ └── Bracket_fem1.fem
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│ ├── optimization_config.json
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│ └── workflow_config.json
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├── 2_results/
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│ ├── study.db
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│ └── optimization.log
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├── run_optimization.py
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├── reset_study.py
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├── README.md
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├── STUDY_REPORT.md
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└── MODEL_INTROSPECTION.md
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```
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---
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## 7. Quick Start
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```bash
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# 1. Discover model outputs
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python run_optimization.py --discover
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# 2. Validate setup with single trial
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python run_optimization.py --validate
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# 3. Run integration test (3 trials)
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python run_optimization.py --test
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# 4. Run full optimization
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python run_optimization.py --run --trials 100
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# 5. Resume if interrupted
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python run_optimization.py --run --trials 50 --resume
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```
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---
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## 8. Results Location
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| File | Description |
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|------|-------------|
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| `2_results/study.db` | Optuna SQLite database |
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| `2_results/optimization.log` | Structured log file |
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| `2_results/pareto_front.json` | Pareto-optimal solutions |
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---
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## 9. References
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- [Atomizer Documentation](../../docs/)
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- [Protocol protocol_11_multi](../../docs/protocols/system/)
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- [Extractor Library](../../docs/protocols/system/SYS_12_EXTRACTOR_LIBRARY.md)
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