Optimize surface geometry to reduce stress concentrations. Shape optimization moves existing surfaces without adding or removing material.
When to Use This Skill
Route here when user mentions:
- "stress concentration", "reduce peak stress"
- "fillet optimization", "optimize fillet radius"
- "reshape surface", "smooth geometry"
- "improve fatigue life", "notch optimization"
Route elsewhere:
- Adding/removing material (holes, organic forms) →
/abaqus-topology-optimization - Low-level optimization setup →
/abaqus-optimization - Running the optimization job →
/abaqus-job
Shape vs Topology Optimization
| Aspect | Shape Optimization | Topology Optimization |
|---|---|---|
| What changes | Surface positions | Material presence |
| Result | Smooth surfaces | Holes, organic forms |
| Manufacturing | Traditional machining | Often needs AM/casting |
| Design freedom | Limited | High |
| Best for | Refine existing design | Conceptual design |
Rule of thumb: Use shape optimization when you have a good design with local stress issues. Use topology when starting fresh or need major redesign.
Prerequisites
Before shape optimization:
- ✅ Working static analysis that converges
- ✅ Identified high-stress surface region
- ✅ Full Abaqus license with Tosca (not Learning Edition)
Workflow: Shape Optimization
Step 1: Run Baseline Analysis
Run static analysis to identify stress concentrations. Note peak stress location and magnitude for comparison baseline.
Step 2: Identify Design Surfaces
Ask user if unclear: Which surfaces can be modified? Which must remain fixed?
Only select surfaces that can be modified in manufacturing, are not functional interfaces, and don't have attached features.
Step 3: Define Movement Limits
Get maximum growth/shrink (mm). Typical values: 3-10mm depending on part size.
Step 4: Choose Objective
| User Goal | Objective | Design Response |
|---|---|---|
| Reduce stress concentration | MINIMIZE_MAXIMUM | STRESS (MISES) |
| Uniform stress distribution | MINIMIZE_MAXIMUM | MAX_PRINCIPAL_STRESS |
| Maximize stiffness | MINIMIZE_MAXIMUM | STRAIN_ENERGY |
Step 5: Add Constraints and Geometric Restrictions
Protect critical regions: BC surfaces, load surfaces, mating interfaces, precision features.
Common constraints: volume ≤ initial, maintain planar surfaces, mesh quality.
Step 6: Run Optimization
Set design cycles (20-30) and submit the optimization process.
Key Parameters
| Parameter | Recommended | Notes |
|---|---|---|
| Max movement | 3-10mm | Based on part size |
| Design cycles | 20-30 | More for complex shapes |
| Mesh quality | MEDIUM | Balance speed/quality |
| Smoothing | LAPLACIAN | Prevents mesh distortion |
What to Ask User
If not specified, clarify:
- Which surface to reshape? - "The inner fillet at the L-bracket corner"
- Maximum allowed movement? - "Up to 5mm growth, 3mm shrink"
- Stress reduction target? - "Reduce from 450 MPa to under 300 MPa"
- Volume constraint? - "Keep volume within 5% of original"
Validation Checklist
After optimization completes, verify:
- Peak stress reduced at critical location
- Volume constraint satisfied
- Geometry still manufacturable
- No mesh distortion warnings
- Results converged (objective stable)
Post-Processing
- Compare initial vs optimized stress contours
- Export modified geometry if needed
- Run final validation FEA on optimized shape
- Check manufacturability with CAM or manufacturing engineer
Troubleshooting
| Problem | Likely Cause | Solution |
|---|---|---|
| Mesh distortion | Movement limits too large | Reduce max growth/shrink |
| No improvement | Wrong design surfaces | Verify surface selection |
| Convergence failure | Aggressive optimization | Add smoothing, smaller steps |
| Volume increase | No volume constraint | Add volume ≤ initial constraint |
| "License error" | No Tosca module | Requires full Abaqus |
Code Patterns
For actual API syntax and code examples, see:
Related Skills
/abaqus-optimization- Base optimization API and concepts/abaqus-topology-optimization- For material removal optimization/abaqus-static-analysis- Required baseline analysis