abaqus-shape-optimization

# Abaqus Shape Optimization Skill 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: 1. ✅ Working static analysis that converges 2. ✅ Identified high-stress surface region 3. ✅ 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: 1. **Which surface to reshape?** - "The inner fillet at the L-bracket corner" 2. **Maximum allowed movement?** - "Up to 5mm growth, 3mm shrink" 3. **Stress reduction target?** - "Reduce from 450 MPa to under 300 MPa" 4. **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 1. Compare initial vs optimized stress contours 2. Export modified geometry if needed 3. Run final validation FEA on optimized shape 4. 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: - [Shape Optimization API](references/shape-optimization-api.md) - [Design Variable Setup](references/design-variables.md) - [Geometric Restrictions](references/geometric-restrictions.md) ## Related Skills - `/abaqus-optimization` - Base optimization API and concepts - `/abaqus-topology-optimization` - For material removal optimization - `/abaqus-static-analysis` - Required baseline analysis