Static Loading and Resultant Deformed Surface

[Albigger]

Hello All -

Just getting used to using COSMOS Xpress to do some static loading of a steel plate, with fixed edges (more or less). There is a pressure applied to the surface and one result given is a plot of the solid deformation.

How do I get the deformed surface back into the modeling capability so I can work with it? Is there anyway? I am using basic SW2007.

Thanks.
--Jay

 

[cbrn]

Hi,
you can't.

Regards

 

[jte]

Well, if you export the model to Cosmosm (.gfm or .geo file format) and run it from GeoStar (comes with my SW pro package, may not be free with basic SW) you could save the nodes in their deformed positions. This would at least give you some points to play with. But I'm guessing that learning how to do this will be well beyond the advantage of getting it done.

Generally speaking, there is little advantage to doing what you are proposing. Might help us to help you if you can tell us a lot more about what you are trying to accomplish.

jt

 

[Albigger]

Instead of designing a very rigid, very stable plate (which would add weight/cost/complexity/etc...) I wish to know the expected deformation and compensate for it.

Say for example, I have a flat plate that, under pressure, bows to a set deformation. Instead of actually making a flat plate, I wish to machine a convex bubble shape, such that under pressure it deforms back to a "flat" shape.

--Jay

 

[Albigger]

Also would SW 2008 offer any benefits?

 

[avantibngrant]

You might try to run the analysis with a domed shape and get the max deformation. Then model the sheet with a dome shape of similar height as the deformation. Run it again.
A couple of tries should get you pretty close to flat.
I think 2008 may have a feature in Cosmosworks designer to capture the deformed geometry.
Regards
Neil Grant

 

[jte]

Jay-

So you're trying to do something similar to a flat bed truck trailer which is built with an initial concave down shape and flattens out when loaded. Looks better visually vs sagging when loaded... Aesthetics plays a role in engineering...

One problem you'll run into here is that you have a geometriaclly nonlinear problem. Unless I'm mistaken, you are working with a linear solver...

If you start with a flat plate supported on the edges and apply uniform pressure, the plate will stiffen as it deforms. This is due to the fact that the initial resistance is provided by bending action. After a bit (many texts say 1/2 the plate thickness) of deformation, this assumption is no longer valid as the plate now starts to carry the load thru membrane action.

If you start with a slightly curved plate which you plan to flatten, you face the problem of having a plate which gets softer with deformation.

To get it right, you really need a solver which can handle geometrical nonlinearities (eg SW pro) and step the solution through a gradually applied loading.

jt

 

[Albigger]

This is not driven by aesthetics but rather by geometry requirements. I know I am being vague and I'm sorry about that.


Anyway, jte, I think I am still in the linear region of deformation. The thickness of plate I'm talking is in the 4 to 6 inch range, and the deformation is less than .010" at the maximum point. So the deformation is << thickness.

--Jay