Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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.

Problems of error in the plasticity hardening model: Lamda non positive for plastic points

Please login with a confirmed email address before reporting spam

Hello every experts and comsol users, I made a simulation of laser beam welding and added a temperature dependent plasticity. When the generated stress reaches the initial yield stress, I get the error "Error in elPlastic element. - Detail: Lambda non positive for plastic point". I have seen the same problems of others, but the problems are not solved. I have tried to decrease the tolerance, the size of the meshes and the time step, but it does not work. Are there any problems in my temperature dependent yield curving in attachment? I simply did the same as the example: https://www.comsol.de/model/temperature-dependent-plasticity-in-pressure-vessel-12805. The temperature of simulation is about 1000K and the Laser worded in the first 1.5 seconds and the temperature gradients are very big.

Any help would be appreciated. Thanks in advance.



0 Replies Last Post 19 Mar 2019, 13:15 GMT-4
COMSOL Moderator

Hello Shiyu Li

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

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.