Bearing Fixture PropertyManager

The PropertyManager allows you to simulate the interaction between a shaft and the ground through a bearing. Since the components supporting the shaft are assumed to be much more rigid than the shaft, they can be considered as the ground.The feature is available for static, frequency, linear dynamic, and buckling studies.

To display this PropertyManager:

Right-click Fixtures icon_fixtures.gif and select Bearing Fixture.

Type

Bearing bearing.png  
Cylindrical Face Enables selection of a full cylindrical face or concentric cylindrical faces of smaller angles of the shaft.
Allow self-alignment

Defines self-aligning bearing connectors that allow an unrestricted off-axis shaft rotation. You can define total lateral and total axial direction stiffnesses for a self-aligning bearing.

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   Prevents the selected face from translating or deforming. Allows the selection to rotate about its axis.
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.
Total 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
Total Axial Applies the axial stiffness k(axial) which resists displacement along the axis of the shaft.

Stabilize shaft rotation   Prevents 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.

Symbol Settings

Edit Color   Uses the color selected for the symbols
Symbol Size Sets the size of the symbols.
Show preview   Toggles the display of the connector symbols in the graphics area.