Connector - Bearing

A bearing connector simulates the interaction between a shaft and a housing through a bearing. To define a bearing connector, you must model the geometries of the shaft and the housing.

You can define a bearing connector between split cylindrical faces of a shaft, and cylindrical or spherical faces of a housing.

The surfaces of a shaft and a housing that are connected to a bearing connector can deform relative to each other. The level of relative deformation between the shaft and the housing surfaces depends on the user-defined connector stiffness.

Type

Bearing
For shaft: Cylindrical Face Select a full cylindrical face or concentric cylindrical faces of smaller angles adding up to 360o.
This selection corresponds to the part of the shaft resting on the bearing.
Create split lines to ensure that the bearing connector is only defined on the proper faces of the shaft. You can make the model excessively stiff, if you select the entire face of the shaft.
For housing: Cylindrical face or circular edge of shell Select a cylindrical face, spherical face, or a circular shell edge (if the housing is modeled with shells). This selection corresponds to the part of the housing resting on the bearing.
   

Connection Type

Distributed A bearing connector modeled with the Distributed type connects the reference nodes of a two-node generalized element to a group of coupling nodes on the surfaces of the shaft and housing. One reference node (located at the centroid of the solid shaft section that is resting on the bearing) connects to the outer surface of the shaft. The second reference node (located at the center of the housing section that is resting on the bearing) connects to the housing internal faces. A generalized element connects the two reference nodes, as shown in the following image.

Distributed coupling constrains the motion of the coupling nodes to the translation and rotation of the reference node. Distributed coupling allows the coupling nodes on the selected geometry (shaft or housing) to move relative to each other.
Rigid
A bearing connector modeled with the Rigid type has a similar formulation with a Distributed type connector. The only difference for the rigid formulation is that individual two-node rigid elements connect the reference nodes to the coupling nodes on the surfaces of the shaft and housing, as shown in the following image.

The coupling nodes on the selected geometry (shaft or housing) do not move relative to each other.
Spring
A bearing connector modeled with the Spring type is represented with spring elements distributed radially between the surface nodes of the shaft and the housing, as shown in the following image.

These local springs provide resistance to off-axis rotations of the shaft.

Connector Stiffness

This section refers to the stiffness applied between the two reference nodes of a generalized element and also refers to the stiffness applied to the individual springs for the Spring type.

Each reference node of the two-node generalized element has six degrees of freedom. You can set the lateral, axial, torsional (optional), and tilt stiffness (optional) values of the bearing connector in this section.

Units Specifies the required unit system.
  Rigid (infinite stiffness)

Distributed and Rigid Connection Type

Applies very high stiffness values to the reference nodes of the generalized element.

Spring Connection Type

Applies very high stiffness to the individual springs that are distributed radially between the selected faces of the shaft and the housing.

The selected face of the shaft cannot translate laterally or axially.
  Flexible

Distributed and Rigid Connection Type

Specifies finite axial and lateral stiffnesses to the reference nodes of the generalized element. The selected face of the shaft can translate laterally or axially according to the defined stiffnesses.

Spring Connection Type

Specifies the stiffness of the springs that are distributed radially between the selected cylindrical faces of the shaft and the housing.

You can define total stiffnesses for the lateral and axial direction for connectors with the Distributed or Rigid type, and distributed radial (per unit area) and distributed axial stiffnesses (per unit area) for connectors with the Spring type.

Lateral

Applies the lateral stiffness of the shaft, k, which resists displacement along the direction of the applied load.

For a Spring connection type, the total stiffness K resisting the lateral displacement of the cylindrical face of the shaft (along the direction of the applied load) relates to the radial stiffness per unit area with the equation:

K(total lateral) = 0.5 * k(radial / unit area) * Area

Area = diameter * height * Pi

Axial

Applies the axial stiffness, k(axial), which resists displacement along the axis of the shaft.

Tilt Stiffness Tilt stiffness is available for the Distributed and Rigid connection type.

Applies a tilt stiffness to the reference nodes of the generalized two-node element to resist the bending of the shaft.

To recreate the Allow Self-alignment option, which was available in releases before 2024, set the Tilt stiffness to zero.
  Stabilize shaft rotation Select this option to prevent rotational instability of the shaft (caused by torsion) that can lead to numerical singularities. You can accept the default Automatic option or apply a user-defined torsional stiffness.

The Automatic option applies a minimal torsional stiffness to the shaft's cylindrical face that provides circumferential resistance against torsion.

This prevents the shaft from rotating freely about its axis and eliminates instability.

Symbol Settings

  Edit Color Select a color for the symbols.
Symbol size Set the size of the symbols.
  Show preview Toggles the display of the connector symbols in the graphics area.

Notes

  • Available for static, frequency, linear dynamic, and buckling studies. Not available for composite shells.
  • Use the Split Line tool to define the cylindrical faces for the shaft that are resting on the bearing. For example, use the Split Line tool to create the following highlighted face to apply a bearing connector.

  • To define a bearing connector between a solid shaft surface and a circular shell edge housing, set the Connection Type to Rigid, as shown in the example below.

  • When to use a Bearing Connector A bearing fixture assumes that the components supporting the shaft are much more rigid than the shaft and can be considered as fixed to the ground. When this assumption is not valid and the flexibility of the supporting parts must be included, you should use a bearing connector formulation to simulate the connection. You need to model not only the shaft but also the housing.

    In the example shown below, the bearing connectors are defined between the cylindrical split faces of the shaft and the spherical faces of the housing.