Shrink Fitting

Shrink fitting is encountered in many engineering designs. It refers to fitting an object into a slightly smaller cavity.

Due to normal forces that develop at the interface, the inner object shrinks while the outer object expands. The amount of shrinkage or expansion is determined by the material properties as well as the geometry of the components.

For accurate results, the overlap should be large enough to overcome approximations introduced by meshing. For example, the interference of cylindrical or spherical faces should be larger than 0.1% of the larger diameter at the interface for accurate results. However, for static studies, use the Large displacement option for moderately large interference. Use nonlinear studies for large interference problems.
The contacting faces need not be cylindrical.

Shrink fitting is applied as a local contact condition. You can define a shrink fit contact condition using the Shrink Fit option in the Contact Set PropertyManager.

The following figure illustrates a shrink fit contact condition between two rings. The outer diameter of the inner ring is slightly larger than the inner diameter of the outer ring. The contact condition is defined between the outer face of the inner ring (1) and the inner face of the outer ring (2).

Applying Shrink Fit Contact

You can apply a shrink fit contact between two objects by using the Shrink Fit option in the Contact Set PropertyManager.

To apply shrink fit contact:

  1. In the Simulation study tree, right-click Connections and select Contact Set.
    Selecting Improve accuracy for contacting surfaces with incompatible mesh (slower) for static studies of assembly models with incompatible mesh is recommended.
  2. In the PropertyManager, under Type, select Shrink Fit.
  3. In the graphics area, select the Set 1 contact entities. All entities should belong to the same component.
    Selected entities appear in the Faces, Edges, Vertices for Set 1 box PM_faces_edges_vertices.gif .
  4. Select the Set 2 contact faces. All faces should belong to one component that is different from the component used in step 3.
    Selected faces appear in the Faces for Set 2 box PM_face.gif.
  5. Click PM_OK.gif.
  6. Mesh the model and run the study.