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
• Design Variable Setup
• Geometric Restrictions

Related Skills

• /abaqus-optimization - Base optimization API and concepts
• /abaqus-topology-optimization - For material removal optimization
• /abaqus-static-analysis - Required baseline analysis