Menu

Discussion Forum

New Discussion
Filtrer

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Simple ball compression with contact

Posted 9 mars 2020, 08:45 UTC−4 Structural & Acoustics, Structural Mechanics Version 5.4 1 Reply

Arthur Biomedical Engineering
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hello everyone,

I am trying to solve a simple Solid Mechanics model in which I want to compress a ball in between two plates. The ball and plates are in contact, but for some reason the model takes forever to solve or returns with an error. I always have this problem as soon as I introduce contact between geometries.

I have uploaded the model below. I hope someone can tell me what I am doing wrong.

Thanks a lot!

-------------------
Avk
1 Reply Last Post 9 mars 2020, 10:55 UTC−4
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 5 years ago 9 mars 2020, 10:55 UTC−4
Updated: 5 years ago 9 mars 2020, 11:09 UTC−4

Hi,

Your model is severely underconstrained. The ball can roll in arbitrary directions, and the upper plate is free to float in the vertical direction. Once contact is established, this may not be a problem, but then some friction would also be needed to avoid that the ball slides.

Also, the fixed constraint at a point in the ball will create a singularity, where the material model will break down if you were to get that far.

I suggest that you add a suitable set of springs to suppress the singularities. This is discussed in the user´s guide. Also, employing symmetry will both speed up the analysis and stabilize the model. .

-------------------
Henrik Sönnerlind
COMSOL
Hi, Your model is severely underconstrained. The ball can roll in arbitrary directions, and the upper plate is free to float in the vertical direction. Once contact is established, this may not be a problem, but then some friction would also be needed to avoid that the ball slides. Also, the fixed constraint at a point in the ball will create a singularity, where the material model will break down if you were to get that far. I suggest that you add a suitable set of springs to suppress the singularities. This is discussed in the user´s guide. Also, employing symmetry will both speed up the analysis and stabilize the model. .

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content