Calculating forces on a flywheel.

[RChristians]

Hi,

I am a new COSMOS 2007 user and I have a question concerning te constraining of a flywheel. When I create a flywheel, a cylinder on an axle, I can apply a centrifugal force to te part.

The constraints however form a problem, which constraint should be applied to simulate rotation? And where should this be applied?

Thanks for your input.

 

[sloth4z]

There really isn't a direct answer to your question, but here is my two cents.

If you want to model a formula you would see in a text book (for example: deflection in the shaft due to gravity) you can use bearing connectors. Right click "Loads/Restraints" and select "Connectors" then select "Bearing". Ball bearings are usually what I use and then select "flexible". For the first stiffnes value insert something high like 1e9 and insert 0 for the second. This allows the bearing to pivot like a standard ball bearing but it won't move that much up or down (That high of stiffness means 1 billion pounds will move the pedestal 1 in). It is kind of like inserting a bearing in your model and fixing the base of the bearing. You should also split one end of the shaft with a pie section to get a point at the center. Restrain that point along the axis.

You also have the following options depending on your conditions. For stress studies with centrifugal loads only:

I. Your best bet is to take a pie section and use symetry restraints, if available. You will also need to restrain one endpoint at the center of the shaft along the axis' direction.

II. With most of my studies I am not interested in the shaft so I remove it completely. I then restrain the ID face of the hub in rotation and radial directions. I also restrain one edge of the ID Face in the axis' direction.

For frequency studies you want to use either bearing connectors or nothing. No restraints will yield the standard 6 free body modes that you can ignore.

If you can't use any of these suggestions let me know what you are doing (loads specifically) and we should be able to figure something out. Hope this helps!!