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Cosmos constraint in the shape of an unmodeled surface?

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BrettPEC

Mechanical
Sep 10, 2003
2
Hi,
Moderate 3-D and limited FEA experience here, but no SW time. I need to define a displacement constraint on a flat surface in the shape of a circle which is not on the part in question. There is a square x-section ring sitting on 3 circular posts to which it is bolted, and I need to constrain the ring (which is modeled) to the end-surfaces of the posts (which are not). Can I do that?

Thanks a lot
 
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I'm no FEA expert either, but if you want to constrain a part where it touches something else, you have to put the constrains on it if you don't want to include the rest of the assembly.

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You must figure out, in your part, wich movements are constrained (don't forget that you have 3 translactions and 3 rotations) by.

You must add one constraint for each restrained movement (Force X restrained translaction; Moment X restrained rotation).

But, to add the constraints, you must select enteties on which they'll apply (surfaces, edges,...). You must decide what better simulate the real assembly method. You mabe need to create addicional features to the part (like split curves) in order to have a good "real" model.

Regards
 
I am not sure I completely understand your model, but you can create a sketch of the cross section on the face it would be contacting. Then, rebuild, select the sketch and the face and do an Insert > Curve > Split Line. This will create a separate selectable face on the main face to which you can apply your loads.

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If I understand dsi's reply:

I need to create a new sketch on the surface that does exist in my model, and sketch those surfaces that contact it but do not exist in my model. Will I then be able to create a displacement constraint (Cosmos constraint, not an assembly constraint) distributed across the shape of that new sketch?

Thanks a lot for your help,
Brett
 
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