Learning Forum

[ActiV]

Hi, I'm performing a three-point-bending test in 2D, but the model was floating so I added an earth gravitational force, amongst the suggestions provided in my previous post: /forum/discussion/comment/131420.However, the gravity force is making my model (the middle bar/specimen) disappear during the unloading phase. It's shifting very far downwards. Probably I'm missing a constraint or boundary condition, but I can't figure out on my own what the problem is. Is there a boundary condition missing in my setup?

B=fixed.

C=-2mm displacement in 2 steps.

D = 0 displacement in x direction.

Two frictional surface contacts are defined.

[Akshay Maniyar]

I have tried creating a similar model and it is working fine. I tried creating a smaller edge on surface near support. You can also try using no separation contact, if that serves your purpose.
I will attach the model for your reference. Please check, if it solves your issue.
regards Amaniyar

[ActiV]

thank you so much for the effort, I do appreciate it. However, I'm using Ansys version 19.0 and I get a pop-up window saying you have a newer version:

Would it be possible for you to save the file in an older version? I only have a university licence supporting version 19.
I added my files as a zip file (didn't know this was possible before, but .7z is working). Maybe you can see any differences in methods, if the above is not working.
Thanks in advance.
Regards Thomas


P.s. just to make sure, you also simulated the releasing of the specimen, right? So a displacement from 0 to e.g. -2mm, back to 0.
P.p.s. I tried no separation contact, but then each node sticks to the surface and you get an inaccurate simulation. Unless there is a way to have a contact to contact no seperation.

[Akshay Maniyar]

Sorry, but I don't have 19 version. The least version I have is Ansys 2020R1. You can try to download latest student version (2021R2) and then you can open the above model. Also, I will explain the settings have used. I think the issue is because of contact. Yes, I have displaced it with 5 mm and again removed that displacement.
Please try this settings, it should solve your issue. I have attached the deformation animation which I got.
Regards Amaniyar

[ActiV]

I downloaded the latest 2021 version of Ansys student, as you suggested. However, I can't find the attached file from you previous post anymore? Would you be willing to share the file again, so I can open it? Thanks

[Akshay Maniyar]

Hi @ActiV Sorry for the trouble. But as a Ansys employee we are not allowed to share models on forum. So, it is removed.
Have you tried the changes I have mentioned in above post? Is it working with those changes?
regards amaniyar

[ActiV]

that's unfortunate. Would be easier to compare files for any differences.
However, updating from Ansys version 19.0 to 2021 R2 magically solved all issues..
Thanks so much for your help again.
Best regards, Thomas

[Akshay Maniyar]

That's great. With every version, solver will be updated. May be that solved your issue.
Regards Amaniyar

[ActiV]

the only difference I could find between your three-point-bending simulation and my simulation was this sketched line in the model. Did you add this on purpose and if so, why and how? Does it enhance contact simulation? It removes the point contact, so maybe it's used to force a non-compatible mesh? See yellow line in the picture below.


Thanks in advance Thomas