bearing load¶
Module: solid
Category: load
Type string: "bearing load"
Parameters¶
| Name | Description | Default | Units |
|---|---|---|---|
scale |
scale | 1 | [] |
force |
force | {0,0,0} | [] |
symmetric_stiffness |
symmetric_stiffness | true | [] |
linear |
linear | false | [] |
shell_bottom |
shell_bottom | false | [] |
profile |
profile | 0 | [] |
Description¶
A bearing load can be applied on a cylindrical surface that represents a bearing journal, or the portion of a shaft that is supported by a bearing journal. This load gets prescribed as a non-uniform compressive pressure distribution on that surface, representing the radial component of the bearing load. (The axial component of a bearing load may be prescribed using the surface force presented in Section Surface-Force.) The non-uniform pressure distribution may be sinusoidal or parabolic. It gets distributed over a ±90 degree arc relative to the loading direction, which is specified as a force vector. The user is expected to specify the bearing force in a plane perpendicular to the axis of the cylindrical bearing surface. Otherwise, only the projection of the bearing force onto that plane will be prescribed as the radial bearing load. For example, a bearing load may be specified as
<surface_load type="bearing load" surface="BearingSurface1">
<scale lc="1">1000.0</scale>
<force>0.707107,0.707107,0</force>
<profile>1</profile>
</surface_load>
In this example the bearing load is in the xy-plane, oriented at 45 degrees from the x-axis. The surface BearingSurface1 should be a cylinder with its axis along the z-direction. The pressure distribution is parabolic (profile=1), and the alternative option is sinusoidal (profile=0). In general, a parabolic distribution produces a higher (often more realistic) central peak pressure on the bearing surface. An optional loadcurve can be associated with the scale as shown in this example, to scale the prescribed bearing force as a function of time. Alternatively, the user may assign a loadcurve to the force.
Additional options are available for a bearing load, including symmetric_stiffness, linear and shell_bottom as outlined in Section Pressure-Load. When the linear flag is set to false, the pressure prescribed on the bearing surface is adjusted to account for the change in area and orientation of each face, caused by the finite deformation of the bearing surface. However, the bearing radial force direction remains unchanged with deformation. It is recommended to set the symmetric_stiffness flag to false when performing a finite deformation analysis.
The bearing load is always prescribed as a compressive load on the selected bearing surface. Therefore, it is recommended to select a complete cylindrical surface on which the bearing load is prescribed; the solver automatically determines which faces of the selected surface must be loaded in compression and which of those have zero pressure prescribed on them, based on the vectorial orientation of the bearing force. If the user selects a semi-cylindrical surface as the bearing surface, it becomes the user's responsibility to ensure that the prescribed bearing force bisects the 180 degree arc of that surface. Otherwise, the analysis may produce unexpected results, due to unevenness of the pressure distribution about the force's line of action. If the user selects a surface with a smaller arc than ±90 degrees, the pressure will not reduce to zero at the straight edges of the surface, though the pressure will be scaled to produce the prescribed force magnitude along the bearing force direction.