Steel structures

[Ignicolist]

Hello!

I´m designing some steel structures to support some brakes.

This structures consist on welded steel plates (aprox. 20mm thickness).
At the beginning, I did some analytical calculations to dimensions them. However, the structures are more and more complicated and hand calculations are not so easy.

It is possible to calculate this structures with FEM?
I assume that weldings can't be calculated with FEM (at least not easily), but I also have problems to calculate the structures due to stress concentrations.
I have enclosed one 3D file of one "simple" structure and the FEM result (I begin with and old easy structure). I would be very pleased if someone could show me how to decide if the max. stress are stress concentrations or it could be dangerous. As all the plates al "bounded" and they have sharp edges, I expect to have stress concentrations always.

Thanks in advance and best regards,

 

[chicopee]

Are you able to have this drawing in PDF, otherwise, I can not open it.

 

[dhengr]

Ignicolist:
I can’t see your attachment in that format. Show it as a PDF file. Show some loads, dimensions, reasonably accurate proportions, etc. in your sketches. Tell us what you are really trying to do. If you don’t have a fairly good feel for these kinds of structures, can’t sketch them meaningfully, and can’ do a reasonably good long hand analysis, you will have trouble modeling the structure and determining what to make of any high stresses shown in the FEA output. Welds are particularly hard to model and will more often than not show high stress points/locations. Quality of welding and weld detailing almost always trumps what appears to be a stress concentration in the FEM output.

 

[drawoh]

Ignicolist,

RAR is an archive format like ZIP. I don't feel like opening it either. A sketch in PDF format is way better for us, and probably more secure for you.

--
JHG

 

[drawoh]

Ignicolist,

One more thought, without looking at your drawings...

How critical is this thing for safety? If you are not confident in your use of FEA (been there, done that), what do you expect us to accomplish? Your problem could be that you have not managed the software correctly. It could be that you have not applied the loads correctly. We may understand your software. We don't understand your machine.

Your question probably should be asked in the forum for whatever software it is you are running.

If you are not comfortable with your structural design in general, you should be talking to an experienced engineer at your site.

--
JHG

 

[81buckeye]

First, I agree with the other posters that a PDF is infinitely easier to deal with in this forum. I was able to install an RAR unarchive tool and view your problem. It looks as though you have already performed an FEM analysis on your simple structure and therefore I would assume you could do the same for your current problem. As to your question about FEM on welds, yes it is possible. Autodesk Inventor can model welds and handle the FEM analyis. If you're worried about the strength of the weld, you could simply reduce the material properties. Alternatively, you could go to the trouble of creating your solid model with "weld material" added as a separate component and rigidly attach it to your part, give it its own material properties, and run your analysis. In any case, your problem is able to be solved. But Autodesk Inventor