Menu

Discussion Forum

New Discussion
Filter

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.

A negative value of J integral before cracking

Posted May 16, 2023, 6:40 p.m. EDT 1 Reply

dingchuan xue
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi all, I wonder if you have ever got a negative value when computing the J integral? In structure mechanics module, I add a thermal strain which can evolve with time. In this case, the J integral is a negative number. It seems that the thermal strain affected the computational process. Any solution to this problem?

1 Reply Last Post May 22, 2023, 7:50 a.m. EDT
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 2 years ago May 22, 2023, 7:50 a.m. EDT

The derivation of the standard path independent J-integral makes use of the fact that the stress tensor is divergence-free. This rules out (most) body loads, as well as thermal strains.

A correction term (a surface integral) is needed. You can find an expression for this term (Eq. 26) in https://www.researchgate.net/publication/200092866_Numerical_Aspects_of_the_Path-Dependence_of_the_J-Integration_in_Incremental_Plasticity .

-------------------
Henrik Sönnerlind
COMSOL
The derivation of the standard path independent J-integral makes use of the fact that the stress tensor is divergence-free. This rules out (most) body loads, as well as thermal strains. A correction term (a surface integral) is needed. You can find an expression for this term (Eq. 26) in .

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