Help for basic modelling 1

[sushi75]

Hello!

I'm fairly new on the wonderful world of FEA, and I'm having a bit of hard time. Based on a simple example, a tension plate with a hole, I struggle and wonder if I really got the essence of FE... :-((

I really want to have a clear idea of the problem (the statement rubbish in, rubbish out makes sense now!)

You can see attached an illustration of the model with Femap.

Basically, I modeled 1/4 of the structure (symmetry), and what I try to is to have a refine mesh near the hole.
So I have created additional curves defining the surfaces where the mesh will be refined.

If I create several surfaces, individually meshed, I have pretty much the meshing I want, but it's like having several surfaces "disconnected" so it doesn't really represent the structure.

If I just have 1 surface with curves on it, and I create nodes on these curves, when meshing the surface, the nodes created on the diagonal are ignored (see in picture where the QUAD are not connecting the nodes created on the curve).

Thus, I think I misunderstood the art of modeling...so any help is more than welcome!

Hope this was clear enough, if not don't hesitate to ask for clarifications.

Massive thanks in advance!!

Tom

 

[rb1957]

I think you're using FeMap (the screen background looks like it); post on the FeMap forum would get more informed replies.

In any case, whatever FEA, you should be able to ...
1) mesh the sides of the quads (rather than the quad surface) and that way both quads (on either side of the edge) will have the same mesh; or
2) mesh the quad elements more carefully, change the number of nodes on one side at a time so you can see how it's interpreting the quad's sides, and that way mesh both quads with the same nodes and spacing; or
3) use the "co-incident node" test to move the nodes to an average position (least preferred).


another day in paradise, or is paradise one day closer ?

 

[IceBreakerSours]

Go through a couple of chapters on fea on solidmechanics.org. One chapter discusses this particular problem at length.

Are you new to this forum? If so, please read these FAQ:

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083

 

[ShellsPlatesMeshes]

You may want to have a look at the following webpage; it contains detailed analysis of the problem that you are solving:

http://mechanics-of-solids.awardspace.info/example1.htm

Hope this helps.

 

[dwallace1971]

The FEMAP documentation has a series of tutorials. This is a good place to start. I believe that this exact problem is presented.

"On the human scale, the laws of Newtonian Physics are non-negotiable"