Using separate contact behavior on unloading vs loading

Submitted by willroc7 on Tue, 01/24/2012 - 16:46

Is it possible to use a separate contact law (force vs displacement) on unloading versus what is used during loading? Thanks in advance!

Forums:

moritzhoefert | Wed, 01/25/2012 - 09:02

You could assign type 1 to your particles while you are loading the silo, then change the type to 2 and then unload.

ckloss's picture

ckloss | Wed, 01/25/2012 - 09:11

Currently there is no Walton-Braun style or similar in LIGGGHTS, but of course it would be possible to implement that. I got some code from Sam Bateman / US NRL where they started with that, but I currently have no time to work on that. If you are interested, let me know and I can give you the code and/or connect you with Sam.

Cheers, Christoph

maxxum | Mon, 05/13/2013 - 12:27

Hello,
I wonder if the Walton-Braun is now included in LIGGGHTS. On similar lines, is there a list of contact models that are available with the software along with their formulation (equations)?

Thanks

ckloss's picture

ckloss | Tue, 05/14/2013 - 12:51

>>I wonder if the Walton-Braun is now included in LIGGGHTS.
No - but this would be fairly easy to code

>>On similar lines, is there a list of contact models that are available with the software along with their formulation
See doc of pair gran. I know it's not in a good shape at the moment, but there's no one volunteering to clean this up :-)

Christoph

maxxum | Wed, 05/15/2013 - 11:54

Thanks for the response. One day hopefully I will be able to code and contribute :)
I do see a hooke/history/hysteresis model in an example, which can do plastic deformation combined with adhesion. Is a documentation entry for this model in the works? Until one gets a hang of the actual code, it is a little hard to figure out what parameters to use with that model.
So the next question is, how does one locate the piece of code where the contact model was written?

aaigner's picture

aaigner | Fri, 05/17/2013 - 12:05

Hi Maxxum!
Until now I have not written the documentation for the hooke/history/hysteresis pair style. It is based on the work of Stefan Luding [Luding, S. (2008). Cohesive, frictional powders: contact models for tension. Granular Matter, 10(4), 235–246.].

The pair style is implemented in the files, pair_gran_hooke_history_hystereses.*.

Cheers,
Andreas

Mohammad Manjiu... | Tue, 10/02/2018 - 08:52

Hi all,

I have read all of the above comment, I think I can get some idea from here, I want to change pair gran hertz/stiffness model as it has plastic and elastic deformation upon the applied force. But I want a history remains to it when I stop applying force on particle the particle should not go to the initial particle position the particle should be in the position where it started to the plastic deformation. Thanks