I have a simple aircraft structural design project, in which I need to design an elevator hinge under specific shear and normal stresses. As expected, I added a bearing in the axis of deflection.
The objective of the project doesn't require modelling the work of the bearing itself, but still I need to take into account the additional stiffness the bearing adds to the structure.
What is the best way to include that stiffness or model the additional structural influence of the bearing?
I am using ANSYS Mechanical module as FEA software.
Hi Mario,
I think that the bearings can be regarded with bushing joint. You can use the just bearing rings and add the bushing between inner and outer ring. My Suggestion use the radial and axial stiffness values of the bearing from the bearing producers web site.
For example you will get something like 160 kN/mm radial stiffness. Add 160 kN radial force on your bearing structure and then change the stiffness value until you get a 1 mm deflaction to get similar stiffness as in reality. Here your bushing represents the stiffness of the bearing balls and the bearing shield.
Only problem could be about defination the rotational stiffnesses. Because, when the rotational stiffnesses werent defined, you will have 3 DOF in the structure. To solve this problem you can model a bearing with bearing balls and the bearing shields. Apply the same process as described in the previous passage. But differently change the elastic modulus of the bearing balls and the bearing shield (maybe orthotropic material could be necessary). When you are done wtih the elastic modulus of the bearing balls and the bearing shields, you can add moment about three axis and find out the rotational stiffness of the structure from the displacement. Thus, you can add the bearing rotational stiffness values into your bushing joint.
Best regards...
Thank you very much for the idea. Unfortunately, I don't have that information available. I have been trying to find a way to roughly approximate the stiffness based on load deflection relationships using Hertzian's theory of contact, but I am not sure about the validity of this approach. The bearing, I am using, is the KSP6.
Apparently a complete dataset of this type of bearing is available at
http://datasheets.globalspec.com/ds/50/AlpineBearing/24FAEA9F-164B-4B38-BA21-6390936FD2C9
If you cannot find the data you need there, a good estimate may be based on a similar type of bearing produced by another firm, provided that you know the essential information (material, dimensions, Conrad-style or slot filled, full complement design)
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