Singularities (or not...) in 3D flange model on Ansys Workbench
Singularities (or not...) in 3D flange model on Ansys Workbench
(OP)
Hi there!
I have been reading some posts on eng-tips about singularities, so the reason I am posting this thread is that I can't quite understand what type of singularity I'm getting on my analysis. I suspect there is one because as i refine my mesh, the maximum value for the von-mises stress on the flange keeps rising with no signs of stopping. This is a problem because I want to guarantee that the yield stress for my material isn't reached. And since there is no convergence of the stress value, i can't do that.
The images i'm attaching are successive refinements and corresponding stress distributions. I hope someone can lend me some insight into the subject, as my thesis presentationnis close and I should be able to produce reliable results.
It is part of the top face of the flange. The elements are hexahedral with 20 nodes. I applied a 10 kN force in a washer that sits on the shown face.
Thank you in advance for looking at this!
I have been reading some posts on eng-tips about singularities, so the reason I am posting this thread is that I can't quite understand what type of singularity I'm getting on my analysis. I suspect there is one because as i refine my mesh, the maximum value for the von-mises stress on the flange keeps rising with no signs of stopping. This is a problem because I want to guarantee that the yield stress for my material isn't reached. And since there is no convergence of the stress value, i can't do that.
The images i'm attaching are successive refinements and corresponding stress distributions. I hope someone can lend me some insight into the subject, as my thesis presentationnis close and I should be able to produce reliable results.
It is part of the top face of the flange. The elements are hexahedral with 20 nodes. I applied a 10 kN force in a washer that sits on the shown face.
Thank you in advance for looking at this!





RE: Singularities (or not...) in 3D flange model on Ansys Workbench
RE: Singularities (or not...) in 3D flange model on Ansys Workbench
RE: Singularities (or not...) in 3D flange model on Ansys Workbench
RE: Singularities (or not...) in 3D flange model on Ansys Workbench
Personally I prefer not to use CAD models whenever possible as it takes longer to fix them than it does just to build the geometry yourself. Generally if you build the model use symmetry when possible and also check the mesh to make sure there are no gaps.
RE: Singularities (or not...) in 3D flange model on Ansys Workbench
If this is the case, your contact parameters might be too stiff for sliding mechanism between the 2 contacting parts (actually 8 contacting parts in your case - given that you have 4 of these mechanisms in every corner).
And as you are refining it, you are hitting the jackpot more and more as your domain (elements) is getting "more sensitive" with decreasing mesh sizes.
This is the only thing I can think of. Not very familiar with Ansys, above comment was only by looking at the stress & boundary condition photos. If you could put the Ansys file somewhere, someone knowledgeable with Ansys would definitely catch what is wrong at once.
Spaceship!!
Aerospace Engineer, M.Sc. / Aircraft Stress Engineer
RE: Singularities (or not...) in 3D flange model on Ansys Workbench
My thanks to corus and aerostress82 for helping me solve this problem!
Best regards!
RE: Singularities (or not...) in 3D flange model on Ansys Workbench
I think stress engineering is a very critical profession and you will also find lots of mistakes (already made) in your future FEA projects as well. This is mostly due to teams not discussing things at full length - or trying to look like they know what they are doing whereas they actually don't..
Let's clear whatever we can here on this website and in our companies, so that the safety of others is "never" compromised..
Spaceship!!
Aerospace Engineer, M.Sc. / Aircraft Stress Engineer