abaqus-contact-analysis

name	abaqus-contact-analysis
description	Analyze multi-body contact. Use when user mentions parts touching, friction between surfaces, bolt-plate contact, press fit, or assembly with contact.
allowed-tools	["Read","Write","Edit","Glob","Grep","Bash(abaqus:*)","Skill"]

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