Simplify Bearing for analysis

[Max.H.Pour]

Hi,

I am trying to simplify a pair of tapered roller bearings for analysis. The reason I am doing this is Nastran In-CAD cannot mesh the bearings or at-least I don't know hoe to do it.

Any thoughts? 

Thanks!

[shigeaki.k]

Hello @maxhDL7VT,

are you able to give a bit mode information e.g. are you looking at modelling the loading between the bearing and the shaft? 

Incidentally, in Nastran In-CAD there is a "bearing Load" type load that represents the typical compressive load distribution that occurs in contact areas between shafts and bearings or bushings.

You can find more information here.

Regards,

Kino****a S.

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[Max.H.Pour]

Hi shigeaki.k,

Thanks for the reply. Actually I am trying to simulate a model of Wheel, shaft and 2 tapered roller bearings. The issue is that Nastran is not able to create a mesh model for the 2 bearings and keep sending the Meshing failure message. I tried to simplify the bearings original DWG but still this gives you less accurate results.

Thanks 

[shigeaki.k]

Hi @Max.H.Pour,

are you able to post some screenshots, as well as posting what the error is? What setting(s) are you using for the mesh?

Regards,

Shigeaki K.

[Max.H.Pour]

Good day shigeaki.k, 

Please have a look at screenshots. Well, I tried to get rid of Fillets and still getting this error message.

I am using the default setting for the mesh only refining the mesh size to 5 mm or less for the areas of interest.

[shigeaki.k]

Hello @Max.H.Pour,

thank you for the screenshots. I can see that you have tried to individually mesh the bearing. Could you tell me if the bearing is a single part i.e. from a third party in a neutral file format?

For example, I use Inventor and with a non-Inventor file format, I had to convert the single part to an assembly of parts so meshing could be done more easily. 

You could also play around with the mesh settings. In most cases, I only change the element size, "Refinement Ratio" or "Max Element Growth Rate" or combination of them. I don't tend to touch the other parameters. You can find more information on the meshing parameters here. 

With Regards,

Shigeaki K.

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[Max.H.Pour]

Hello shigeaki.k,

Thanks for the reply. The bearings come from our vault library(content center) as an Inventor file format and I have assembled them within Inventor environment If this is what you were asking?

I can see in the screenshot the bearing is successfully meshed. Can you please tell me what settings have you used?

Thanks

[John_Holtz]

Hi maxhDL7VT,

I am curious: what is the purpose of including the bearings in your analysis? Are you designing the bearings? Are you trying to include the stress or displacement in the bearings in your analysis?

Normally, the bearings are viewed as constraining the model. So instead of trying to model the bearings as physical parts, maybe it is possible to use some type of constraint that give the same behavior as the bearings. This would give you the stress and displacement in the rest of the model.

Even if the bearing were between two parts of the model, such as connecting the shaft to the housing, I would model the bearing as two solid rings that meet at the center of the rollers, with some type of contact where the rollers would be located. This would be simpler to mesh, and instead of having contact between N rollers and two races, there would only be contact between the mating faces of the races.

[Max.H.Pour · Accepted solution]

Hi John,

I would like know which model is more accurate since I am getting different results from so many different simulations I have been running. This concerns me a bit to be completely honest.

In my model as well, the bearings are fixed constraints and loads are applied to specific areas on wheel surface. I edited the bearings original sketch to -as you mentioned- a ring and this is much simpler to mesh.

Thanks for your help.