Interpretation of finite element analysis results

Hi,

Recently started with FEA - loving it, at least the modelling / load application part.

Interpreting the results is tricky - particularly around where loads are applied.

Got a project (no pics sorry) which has a drilled hole in a plate, and have applied the load as a a pressure, representatve of a bolt bearing on the face.

When doing a linear static solve, area around the contact point goes white (i.e. stress capped at yeild), then rest of region up to the closest edge goes to acceptable stress levels (using von mises).

Using hand cals for tearout and bearing, the plate is fine. Using FEA confuses things, and what do i write in a report to say that the lug won't fail (despite the yeild).

Should get some pics in a few days.

Thanks,

 PhysOrg.com engineering news on PhysOrg.com >> Researchers use light projector and single-pixel detectors to create 3-D images>> GPS solution provides 3-minute tsunami alerts>> Single-pixel power: Scientists make 3-D images without a camera
 Why would the FEA show failure if your hand calcs (usually conservative) do not? Are you sure that your material properties and load application are correct in the FEA?
 How is your load applied...on the geometry or on the mesh? What is your mesh density in that area... do you have a fine enough mesh? If you've applied the load on the geometry (surface), and you have a very coarse mesh, you may have issues. What pre-processor & code are you using... some make it difficult to refine the mesh locally without affecting the entire mesh. How are you viewing the results... are you looking at contours that are averaged at the element centroid?

Interpretation of finite element analysis results

My guess is that you have applied the stress around the hole as a pressure, and when you look at the maximum it is giving you the stress at the hole, which will have a concentration factor. What you want is the stress on the plate outside of the area where this pressure is being applied. When I do this, I make the part of the plate that the bolt is acting on a different element to that of the rest of the plate so I can turn it off and it only shows me the outside results.