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Tie Constraint

In one sentence: Bond two faces permanently together so they move as one — even if they do not overlap or are not initially touching.

Overview

Workbench: FEM
Menu: FEM → Model → Mechanical Boundary Conditions → Tie Constraint

Bonds two faces by tying their nodes — the two faces always move together, with no separation or sliding. Unlike Contact, Tie is always active: once tied, the faces cannot separate.

When to use Tie vs Contact

Situation Use
Two faces that are always fully bonded (glued, welded, brazed) Tie
Two faces that may separate or slide Contact
Mesh transition between coarse and fine regions Tie

Tied mesh connections

Tie is commonly used to join two mesh regions with different element sizes — for example, a refined mesh around a notch tied to a coarser mesh for the rest of the body. The constraint interpolates between the two mesh densities automatically.

See also