abaqus-contact-analysis

# Abaqus Contact Analysis Workflow This skill guides multi-body contact analysis setup. It's a **workflow skill** - use it when analyzing assemblies where surfaces touch, slide, or separate. ## When to Use This Skill **Route here when user mentions:** - "Parts touching each other" - "Contact between surfaces" - "Friction between parts" - "Bolt and plate contact" - "Press fit / interference fit" - "Multi-body assembly" - "Parts sliding on each other" - "Impact analysis" - "Bearing contact" **Route elsewhere:** - Single-body analysis → `/abaqus-static-analysis` - Just defining contact properties → `/abaqus-interaction` - Only boundary conditions → `/abaqus-bc` ## Prerequisites Before contact analysis setup: 1. Separate parts exist (at least two bodies) 2. Parts are positioned in assembly with appropriate gap/interference 3. Material properties defined for all parts 4. Basic understanding of which surfaces will touch ## Workflow Steps ### Step 1: Identify Contact Pairs Ask the user: - Which surfaces will touch? - Is there an initial gap or interference? - Will surfaces slide or remain bonded? ### Step 2: Determine Master vs Slave | Role | Should Be | |------|-----------| | Master | Stiffer material, coarser mesh | | Slave | Softer material, finer mesh | **Rule:** Slave surface nodes cannot penetrate master surface. ### Step 3: Choose Contact Type | Scenario | Approach | |----------|----------| | Permanently bonded surfaces | Tie constraint (no slip/separation) | | Sliding with friction | Surface-to-surface contact | | Frictionless contact | Surface-to-surface, no tangential | | Many bodies touching | General contact (auto detection) | | Surface folding on itself | Self-contact | ### Step 4: Define Contact Property Configure normal behavior: - **Hard contact** - Most cases, no penetration allowed - **Soft contact** - For rubber, foam, or gradual engagement Configure tangential behavior (if not tied): - **Frictionless** - Lubricated surfaces - **Friction (Coulomb)** - Specify coefficient ### Step 5: Set Friction Coefficient | Interface | Typical Value | |-----------|---------------| | Frictionless | 0.0 | | Lubricated steel | 0.1-0.2 | | Dry steel-on-steel | 0.3-0.5 | | Rubber on metal | 0.5-0.8 | Ask user if unsure about their specific interface. ### Step 6: Create Analysis Step Contact analysis typically requires: - Nonlinear geometry (nlgeom=ON) - Smaller initial increment (0.1) - More increments allowed (100+) - Minimum increment for convergence (1e-8) ### Step 7: Request Contact Outputs Essential output variables: - CSTRESS - Contact pressure and shear - CDISP - Contact displacement - COPEN - Gap opening distance - CSLIP - Accumulated slip ## Key Decisions | User Need | Configuration | |-----------|---------------| | Bonded joint (welded, glued) | Tie constraint | | Bolted connection | Friction contact + preload | | Press fit | Interference + friction | | Bearing load | Frictionless or low friction | | Impact/crash | Explicit dynamics + general contact | ## What to Ask User 1. **Surfaces:** Which surfaces will touch? 2. **Motion:** Will parts slide, separate, or stay bonded? 3. **Friction:** Dry contact, lubricated, or frictionless? 4. **Gap/interference:** Initial configuration? 5. **Loading:** What pushes the parts together? ## Validation Checklist After setup, verify: - [ ] Master/slave assigned correctly (stiffer = master) - [ ] Contact property has normal behavior defined - [ ] Tangential behavior set (friction or frictionless) - [ ] nlgeom=ON in analysis step - [ ] Contact outputs requested (CSTRESS, CDISP) - [ ] Boundary conditions don't overconstrain ## Troubleshooting | Problem | Likely Cause | Solution | |---------|--------------|----------| | "Severe discontinuity" | Contact chattering | Add stabilization, smaller increments | | "Too much penetration" | Wrong master/slave | Swap roles, refine slave mesh | | "Contact not detected" | Surfaces too far apart | Use adjust=ON or reduce gap | | "Convergence failure" | Difficult nonlinearity | Smaller increments, check friction | ## Code Patterns For API syntax and code examples, see: - [Contact API Reference](references/contact-api.md) - [Common Contact Patterns](references/contact-patterns.md) - [Contact Examples](references/contact-examples.md) ## Related Skills - `/abaqus-interaction` - Contact property details - `/abaqus-bc` - Boundary conditions - `/abaqus-step` - Nonlinear step settings - `/abaqus-dynamic-analysis` - For impact problems