Yade

unloading - servo-control

Asked by Chiara Modenese

Hi there,

have you ever experienced problems with UNLOADING a sample, say from a certain condition, to reach a new stress state? I use TriaxialStressController and I set the same "gain" paramaters as I do when I load. However, oscillations are much bigger in unloading than loading, given the same "gain". I can tune again the control for unloading, but am wondering about the difference between the two cases as I thought the control should work the same way for both loading and unloading.

Thanks a lot for suggestions,
Chiara

Question information

Language:
English Edit question
Status:
Expired
For:
Yade Edit question
Assignee:
No assignee Edit question
Last query:
Last reply:
Revision history for this message
Bruno Chareyre (bruno-chareyre) said : 		#1

This is strange. It should not happen and I never got this problem.
Maybe you go from stress=something to stress=0 in only one or very few
steps? then I would understand it is unstable.
If this is what happens, you could reduce max strain rate (max_vel) to
avoid that.

Bruno

Revision history for this message
Chiara Modenese (chiara-modenese) said : 		#2

On 8 June 2011 17:11, Chareyre <email address hidden> wrote:

> Your question #160730 on Yade changed:
> https://answers.launchpad.net/yade/+question/160730
>
> Status: Open => Answered
>
> Chareyre proposed the following answer:
> This is strange. It should not happen and I never got this problem.
>
Hi, I have solved it by tuning again the parameters involved.

However I have another problem now (I use this thread as it is related to
the servo-control). I would like to assign stress increments in order to
follow a specific stress path (different from the triaxial one) in
stress-control. Would you have any suggestion how to do that using
TriaxialStressController?

Thanks,
Chiara

> Maybe you go from stress=something to stress=0 in only one or very few
> steps? then I would understand it is unstable.
> If this is what happens, you could reduce max strain rate (max_vel) to
> avoid that.
>
> Bruno
>
> --
> If this answers your question, please go to the following page to let us
> know that it is solved:
> https://answers.launchpad.net/yade/+question/160730/+confirm?answer_id=0
>
> If you still need help, you can reply to this email or go to the
> following page to enter your feedback:
> https://answers.launchpad.net/yade/+question/160730
>
> You received this question notification because you asked the question.
>

Revision history for this message
Launchpad Janitor (janitor) said : 		#3

This question was expired because it remained in the 'Open' state without activity for the last 15 days.