Plane Rotation Constraint

In one sentence: Constrain all nodes on a face to remain in the plane of that face — used for cyclic symmetry boundary conditions.

---

Overview

Workbench: FEM
Menu: FEM → Model → Geometrical Analysis Features → Plane Rotation Constraint

Constrains all nodes on a selected face to remain in the plane of that face. The primary use is cyclic symmetry — modelling only one periodic sector of a rotationally periodic structure (turbine disc, bolt circle, fan blade).

---

How cyclic symmetry works

Instead of meshing the full 360° disc, mesh one sector (e.g. 1/24^th = 15°). Apply Plane Rotation to both cut faces to enforce that they deform as mirror images. The solver represents the full disc solution at 1/24^th the cost.

---

Common mistakes and pitfalls

Requires matching mesh patterns on both cut faces

The two sector cut faces must have the same mesh pattern (same node positions) for cyclic symmetry to work correctly. Use Gmsh's periodic meshing option to enforce this.

---

See also

• Transform Constraint — apply BCs in a local coordinate system
• Section Print — output section forces
• FEM Workbench — workbench overview