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.

Solid Mechanics equation doesn't line up with documentation

Please login with a confirmed email address before reporting spam

Hello,

I'm trying to better understand the workings of the solid mechanics module, and I came across an apparent discrepancy between the documentation and the module itself.

The momentum balance equation in the module itself (Solid Mechanics -> Equation) for a stationary solution is:

,

but according to the documentation, the correct equation is:

.

I feel like I must be missing something simple here. Does the solver assume that the strain is small, and therefore ? Or is there maybe one of the gradients in terms of the materials frame and one is not?

Cheers, Adam


2 Replies Last Post Nov 13, 2018, 9:17 a.m. EST
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 5 years ago Nov 13, 2018, 6:59 a.m. EST

Hi Adam,

What you see in the GUI is, as you suspect, the geometrically linear form. If you select the Include geometric nonlinearity check box in the study, the displayed equation will change accordingly.

Regards,
Henrik

-------------------
Henrik Sönnerlind
COMSOL
Hi Adam, What you see in the GUI is, as you suspect, the geometrically linear form. If you select the *Include geometric nonlinearity* check box in the study, the displayed equation will change accordingly. Regards, Henrik

Please login with a confirmed email address before reporting spam

Posted: 5 years ago Nov 13, 2018, 9:17 a.m. EST

Henrik,

Thanks so much, that was indeed the problem!

Adam

Henrik, Thanks so much, that was indeed the problem! Adam

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.