Stress concentration in solid modeled with TET10
Stress concentration in solid modeled with TET10
(OP)
Hi everybody,
I received a very big complex to model. For one of the attachmetn I removed a very big fillet leaving an 90 deg angle. In the simulation I have a peak of stress in that area. Would it be possible to show through an analytical calculation the stress value in that area if there was the radius modeled?
I received a very big complex to model. For one of the attachmetn I removed a very big fillet leaving an 90 deg angle. In the simulation I have a peak of stress in that area. Would it be possible to show through an analytical calculation the stress value in that area if there was the radius modeled?





RE: Stress concentration in solid modeled with TET10
There wouldn't be a way to convert the peak stress from FEA to an actual stress with radius because the peak stress in FEA is a massive error. There's software that does something clever with shells to obtain maximum stress from stresses a small distance away from the corner, without having to model the radius. But I think that's a secret sauce they've invented themselves.
RE: Stress concentration in solid modeled with TET10
RE: Stress concentration in solid modeled with TET10
but in reality I am using Femap that I think doesn't have this functionality.
RE: Stress concentration in solid modeled with TET10
can you make a free body of the part with the fillet, and run it in isolation ?
another day in paradise, or is paradise one day closer ?
RE: Stress concentration in solid modeled with TET10
RE: Stress concentration in solid modeled with TET10
Another more visual and crude option is to check the stresses away from the discontinuity where they are very much continuous and compare it with your corner stress. The ratio of the two will give you the SCF.
EDIT:
Tets are more stiffer than bricks. Use of Tets at corners will give you unrealistic rise of stresses that is more due to tet element's stiff behaviour than corner effect. use bricks and check it yourself.
RE: Stress concentration in solid modeled with TET10
The SCF for a 90 degree internal corner is already known to be infinite so you can't/don't need to estimate it from the ratio of stresses. That would give a wrong finite value.
While it's true that tets perform worse than hexahedra with the same number of nodes, you should have already made sure the results are independent of the mesh so both element shapes should be giving the same results (or both showing no convergence as in this case). If they're not, then the model is already wrong even without the stress concentration. Tets give results that are just as correct as bricks but you may need more of them. Bricks are an optimization to reduce the number of nodes and aren't necessary for correct stresses.
RE: Stress concentration in solid modeled with TET10
You said correctly about SCF but I proposed this way of checking for general feeling of stress concentration. I am just wondering about your following statements.
My understanding is bricks give more correct results than tets for same analysis provided all things are correct(in the sense of analysis setup and physics) and of course with less no of nodes.
RE: Stress concentration in solid modeled with TET10
RE: Stress concentration in solid modeled with TET10
http://www.eng-tips.com/viewthread.cfm?qid=2912
http://www.eng-tips.com/viewthread.cfm?qid=141134
http://www.eng-tips.com/viewthread.cfm?qid=376766
I guess we need to look into past threads before posting answers(me)/questions here.