abaqus-interaction

# Abaqus Interaction Skill Define contact pairs, tie constraints, coupling, and connectors between parts in an assembly. ## When to Use This Skill **Route here when user mentions:** - "Contact between surfaces" - "Friction", "sliding contact", "frictionless" - "Tie constraint", "bonded surfaces", "welded" - "Parts touching", "parts can separate" - "Coupling", "connector", "spring element" - "Join different meshes" **Route elsewhere:** - Complete contact analysis workflow → `/abaqus-contact-analysis` - Fixed supports or displacements → `/abaqus-bc` - Applied forces or pressures → `/abaqus-load` ## Key Decisions ### 1. What Type of Connection? | User Describes | Interaction Type | Key Feature | |----------------|------------------|-------------| | Welded, glued, bonded | Tie constraint | Permanent, no relative motion | | Parts can slide and separate | Surface-to-surface contact | Friction, gap allowed | | Load from point to surface | Coupling | Reference point control | | Spring, damper, hinge | Connector | Stiffness/damping behavior | | Adhesive, delamination | Cohesive | Damage initiation criteria | ### 2. Contact Formulation | Formulation | When to Use | |-------------|-------------| | Surface-to-surface | General contact (recommended default) | | Node-to-surface | Legacy compatibility, special cases | | General contact | Automatic detection (explicit dynamics) | | Self-contact | Folding, buckling, large deformation | ### 3. Typical Friction Coefficients | Surface Pair | Friction Coefficient | |--------------|---------------------| | Frictionless | 0.0 | | Lubricated metal | 0.1 - 0.3 | | Dry metal-to-metal | 0.3 - 0.5 | | Rubber on surface | 0.5 - 0.8 | | No slip (rough) | Use ROUGH formulation | ## What to Ask User If unclear, ask: 1. **Bonded or sliding?** - Bonded (no relative motion) → Tie constraint - Sliding allowed → Contact with friction 2. **Friction coefficient?** - If not specified, suggest typical value for material pair - Frictionless is valid for lubricated or normal-dominant cases 3. **Which surface is master/slave?** - User may not know - guide them (see below) 4. **Can surfaces separate?** - Yes → `allowSeparation=ON` - No (always in contact) → `allowSeparation=OFF` ## Master/Slave Selection Guidelines | Criterion | Master Surface | Slave Surface | |-----------|----------------|---------------| | Stiffness | Stiffer body | Softer body | | Mesh density | Coarser mesh | Finer mesh | | Size | Larger surface | Smaller surface | | Geometry | Flat/convex | Curved/concave | **When in doubt:** The coarser mesh should be master. ## Workflow: Setting Up Interactions ### Step 1: Identify Contact Pairs List all surfaces that interact. For each pair determine: - Type (contact vs tie) - Master and slave assignment - Friction requirements ### Step 2: Create Surfaces Surfaces must be defined on assembly instances before creating interactions. ### Step 3: Define Contact Properties For contact interactions, define: - **Normal behavior:** Hard contact, allow separation - **Tangential behavior:** Friction formulation and coefficient ### Step 4: Create Interaction Assign contact property to surface pair in appropriate step. ### Step 5: Verify Setup Check for: - Correct master/slave assignment - Appropriate initial gap/overclosure - Contact pair is active in correct step ## Common Gotchas | Symptom | Likely Cause | Solution | |---------|--------------|----------| | Contact not detected | Surfaces too far apart | Use `adjust=ON` or reduce initial gap | | Severe discontinuity warnings | Contact chattering | Add stabilization, use smaller increments | | Negative eigenvalue | Wrong master/slave | Swap master and slave surfaces | | Overclosure too large | Initial interference | Use shrink fit option or adjust geometry | | Tie not working | Surfaces not close enough | Increase position tolerance | ## Validation Checklist Before running analysis: - [ ] All contacting surface pairs identified - [ ] Master/slave correctly assigned - [ ] Contact properties defined (normal + tangential) - [ ] Interaction assigned to correct step - [ ] Initial gaps/overclosures within tolerance - [ ] Friction coefficient appropriate for materials ## Code Patterns For API syntax and code examples, see: - [API Quick Reference](references/api-quick-ref.md) - [Common Patterns](references/common-patterns.md) - [Troubleshooting Guide](references/troubleshooting.md)