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
• Common Contact Patterns
• Contact Examples

Related Skills

• /abaqus-interaction - Contact property details
• /abaqus-bc - Boundary conditions
• /abaqus-step - Nonlinear step settings
• /abaqus-dynamic-analysis - For impact problems