Contact Constraint¶
In one sentence: Define a contact pair between two faces — the solver prevents them from overlapping and optionally enforces friction.
Overview¶
Workbench: FEM
Menu: FEM → Model → Mechanical Boundary Conditions → Contact Constraint
Defines a contact pair between two faces that may touch, separate, or slide relative to each other during the analysis. The solver enforces non-penetration and optionally applies a friction coefficient.
Contact types¶
| Type | Penetration | Separation | Friction |
|---|---|---|---|
| Frictionless | Prevented | Allowed | No |
| Rough (no slip) | Prevented | Allowed | Full stick |
| Coulomb friction | Prevented | Allowed | μ coefficient |
Step-by-step¶
- Select the master face (usually the stiffer body).
- Ctrl-click the slave face (usually the more compliant body).
- Choose FEM → Model → Mechanical BCs → Contact Constraint.
- Set the friction coefficient (0 for frictionless).
- Click OK.
Common mistakes and pitfalls¶
Contact requires a nonlinear solver
Contact is nonlinear — the contact area changes with load. CalculiX must run with Geometrical Nonlinearity enabled. Linear static mode does not support contact.
See also¶
- Tie Constraint — bond faces permanently (no separation)
- Solver CalculiX — must be in nonlinear mode for contact
- FEM Workbench — workbench overview