Abaqus Optimization Skill

This skill configures optimization tasks in Abaqus. It's the base module - for complete workflows, route to /abaqus-topology-optimization or /abaqus-shape-optimization.

When to Use This Skill

Route here when user mentions:

• "design response", "objective function", "optimization constraint"
• "SIMP penalty", "material interpolation"
• Low-level optimization setup (not complete workflows)

Route elsewhere:

• Complete topology optimization workflow → /abaqus-topology-optimization
• Complete shape optimization workflow → /abaqus-shape-optimization
• Running the optimization → /abaqus-job

Prerequisites

Before optimization setup:

1. ✅ Working static analysis that converges
2. ✅ Appropriate mesh density
3. ✅ Full Abaqus license with Tosca (not Learning Edition)

Workflow: Setting Up Optimization

Step 1: Understand User's Goal

Ask if unclear:

• What to optimize? Weight, stiffness, frequency, stress?
• What constraints? Volume limit, stress limit, displacement limit?
• Manufacturing? Casting (draw direction), additive (min feature size)?

Step 2: Choose Objective-Constraint Pair

User Wants	Objective	Constraint
Lightest structure that's stiff enough	Minimize volume	Compliance ≤ limit
Stiffest structure at given weight	Minimize compliance	Volume ≤ 30%
Avoid resonance	Maximize frequency	Volume ≤ target
Reduce peak stress	Minimize max stress	Volume ≤ target

Most common: Minimize compliance with volume ≤ 30%

Step 3: Define Design Responses

Design responses are the quantities optimization tracks:

Response	When to Use
VOLUME	Almost always (for volume constraint)
STRAIN_ENERGY	Stiffness optimization
EIGENFREQUENCY	Vibration/resonance
STRESS	Stress-constrained design
DISPLACEMENT	Deflection limit

Step 4: Set Objective Function

The objective is what gets optimized:

• MINIMIZE_MAXIMUM - For compliance, stress
• MAXIMIZE_MINIMUM - For frequency

Step 5: Add Constraints

Constraints limit the design space:

• RELATIVE_LESS_THAN_EQUAL - Percentage (volume ≤ 30%)
• ABSOLUTE_LESS_THAN_EQUAL - Fixed value (stress ≤ 200 MPa)

Step 6: Consider Manufacturing

Constraint	Purpose
Min member size	Prevents thin, unmanufacturable features (3-5mm typical)
Symmetry	Mirrors design about plane
Draw direction	Enables mold/casting extraction
Overhang angle	For additive manufacturing

Step 7: Freeze Critical Regions

Always freeze:

• BC application regions (mounting points)
• Load application regions
• Functional surfaces (mating interfaces)

Key Parameters

Parameter	Recommended	Notes
SIMP penalty	3.0	Higher = sharper boundaries
Volume fraction	0.3-0.4	Start conservative
Min member size	3× mesh size	Prevents checkerboard
Design cycles	30-50	More for complex geometry

Validation Checklist

After setup, verify:

• Task created with correct region
• At least one design response defined
• Objective function set
• Volume or other constraint defined
• BC/load regions frozen
• Manufacturing constraint if needed

Troubleshooting

Problem	Likely Cause	Solution
Checkerboard pattern	No min member size	Add GeometricRestriction
Disconnected result	Load path broken	Freeze more regions
Not converging	Constraint too tight	Relax volume fraction
"License error"	No Tosca module	Requires full Abaqus

Code Patterns

For actual API syntax and code examples, see:

• API Quick Reference
• Common Patterns
• Troubleshooting Guide