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Torque on Anti-Roll Bar
Posted Feb 2, 2017, 8:52 p.m. EST Geometry, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions, Results & Visualization, Structural Mechanics Version 5.2a 1 Reply
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Hello, I am an undergraduate student using COMSOL to perform FEA on an anti-roll, or sway bar, of a formula vehicle for a project that I am working on.
It should be quite simple, but I am just having trouble with applying a torque to one end of the bar. The bar is a cylinder, where one end of the bar is fixed with a fixed constraint, and a torque will be applied to the other end of the bar. I have searched through other posts, and some have said to use point loads or edge loads in different directions to act as a rotational force, but those do not seem to get the desired effect that I am looking for. There does not appear to be an option to just apply a torque or rotational force either, unfortunately.
Can anyone explain how to apply a torque or rotational force? I am using version 5.2a of COMSOL. Any advice or help would be greatly appreciated. Thank you.
Aaron
It should be quite simple, but I am just having trouble with applying a torque to one end of the bar. The bar is a cylinder, where one end of the bar is fixed with a fixed constraint, and a torque will be applied to the other end of the bar. I have searched through other posts, and some have said to use point loads or edge loads in different directions to act as a rotational force, but those do not seem to get the desired effect that I am looking for. There does not appear to be an option to just apply a torque or rotational force either, unfortunately.
Can anyone explain how to apply a torque or rotational force? I am using version 5.2a of COMSOL. Any advice or help would be greatly appreciated. Thank you.
Aaron
1 Reply Last Post Feb 3, 2017, 9:23 a.m. EST
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Posted:
7 years ago
This is similar to this recent thread www.comsol.com/community/forums/general/thread/134732/, except that in your case the torque is aligned with the beam.
The approach is the same: you apply a distributed boundary force that is equivalent to the torque you need. As long as you don't care about local stresses, how you apply those forces is not very important, because of the Saint Venant Principle.
I am attaching a toy model that illustrates that.
In FEA, since there is no degree of freedom associated with rotation in a 3D solid analysis you cannot apply a point torque. Note that in real life, it's kind of the same actually: you cannot apply a concentrated torque: whether you're using a wrench or a screwdriver, you always apply a torque indirectly by applying forces over finite (possibly small, but finite) surfaces or volumes.
Jeff
The approach is the same: you apply a distributed boundary force that is equivalent to the torque you need. As long as you don't care about local stresses, how you apply those forces is not very important, because of the Saint Venant Principle.
I am attaching a toy model that illustrates that.
In FEA, since there is no degree of freedom associated with rotation in a 3D solid analysis you cannot apply a point torque. Note that in real life, it's kind of the same actually: you cannot apply a concentrated torque: whether you're using a wrench or a screwdriver, you always apply a torque indirectly by applying forces over finite (possibly small, but finite) surfaces or volumes.
Jeff
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