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FEA...How to define roller bearing constraint in mechanica ?

vbhuskute
2-Guest

FEA...How to define roller bearing constraint in mechanica ?

Hi,

I am trying to define bearing constraint. I have base plate that is supported by two shafts at either ends. These shafts are supported by bearings so that plate can rotate around shaft axis.

Please advise how should i apply bearing constraints to these shafts ?

Thank you.

8 REPLIES 8

Two methods spring to mind.

The first is to define a cylindrical coordinate system, and then constrain the shaft surfaces with reference to this.  You can then constrain in R (and optionally Z, i.e. axial movement) but leave the Theta (tangential) direction free.  Note that this gives a completely rigid constraint in the other directions, so the shafts will not be able to tilt or deform out-of-round.

The second, and typically more accurate, is to create two points very close together at the centre of the 'bearing'.  Link the shaft surface to one point using a Weighted Link, connect the two points together using a (very stiff) Advanced Spring, and then constrain the second point, leaving one rotation free (and optionally one translation).

A third way would be to use a frictionless contact constraint to a fixed outer sleeve...

Thank you Jonathan

There is a very good technique I've used in the past to capture ball bearing support behavior well. It is posted on PTC's support site here:

http://support.ptc.com/cs/cs_25/howto/mst6864/mst6864.htm

This is similar to what Jonathan has suggested in his second method, but with all the details required (and sample models) to describe the steps needed - see the "inside model" version. If your bearing is a needle roller, you will have a length of support that does not rotate as easily as a ball bearing. You can vary this technique to handle this situation as well.

Thank you chris.

I am having difficulty in creating rigid link. I am getting following error message.

"The dependent side geometrical references may be in conflict

with another rigid/weighted link or constraint"

Hope you can help

I am having difficulty in creating rigid link. I am getting following error message.

"The dependent side geometrical references may be in conflict

with another rigid/weighted link or constraint"

I have often seen this, and I think it is only a warning, not an error.

See whether the model runs.

Then display the results with deformation (ideally animated), and check that the model is moving in a way that you believe is realistic.  If so, it is unlikely that there is a problem with this.

It worked. Thank you Jonathan.

Hi, @ChrisKaswer ,

 I can't able to access the link that you have attached, Can you please help me in this. 

 

Thanks in Advance, 

Theliban Aravindan

With Regards,
T A

You must be logged-in to this PTC customer support system to gain access. In addition, your login may also need to be associated with a customer account that provides access to this area of support - I can't recall off the top of my head.

 

Cheers,

 

Chris

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