Connector - Bearing

A Bearing connector simulates the interaction between a shaft and a housing through a bearing. You have to model the geometries for 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.

Type

Bearing
select_face_cyl.png Selection (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.
select_face_cyl.png Selection (Cylindrical or spherical face or circular edge on shell) Select a cylindrical face, spherical face, or circular shell edge (if the housing is modeled with shells). This selection corresponds to the part of the housing resting on the bearing.
PM_allow_self_alignment.gif Allow self-alignment When selected, you can define self-aligning bearing connectors that allow an unrestricted off-axis shaft rotation.

The pivot point is located at the centroid of the shaft's selected cylindrical face.

When this option is cleared, the cylindrical face of the shaft cannot swing freely in off-axis direction. There is resistance to off-axis rotation due to the distribution of local springs along the shaft. Moments can develop at the shaft's cylindrical face.
A self-aligning bearing connector is insensitive to angular misalignments of the shaft relative to the housing, and offers no resistance to a bending deformation of the shaft. This typically corresponds to a self-aligning ball bearing with two rows of balls and a common concave sphered raceway in the outer ring.

Stiffness

Units  
  Rigid Applies very high stiffness values to the spings that are distributed radially between the selected cylindrical faces of the shaft and the housing.

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

Allows the selected face to deform and axially displace.

You can define total lateral and axial direction stiffnesses for a self-aligning bearing connector, and distributed radial (per unit area) and distributed axial stiffnesses (per unit area) for a no self-aligning bearing connector.

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

stiffness_radial.png Lateral

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

For a no self-aligning bearing connector, 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

stiffness_axial.png Axial

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

  Stabilize shaft rotation Select this option to prevent rotational instability (caused by torsion) that can lead to numerical singularities

Simulation applies springs with low torsional stiffnesses (1/1000 th of the axial stiffness) to the shaft's cylindrical face that provide circumferential resistance against torsion.

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

This option is not meant to prevent the relative rotation between a shaft and its housing so as to resist a significant torque. Consider instead using a Pin connector with the With key (no rotation) option selected.

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, 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.

  • Self-Aligning Bearings. The program internally defines a resistance along the circumferential direction of the cylindrical face. Self-aligning bearing connectors allow an unrestricted off-axis shaft rotation.
  • 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 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 cylindrical faces of the shaft and spherical faces of the housing.