[petsc-users] SNES and TS for nonlinear quasi-static problems

[Matthew Knepley]

On Mon, Dec 19, 2022 at 6:12 AM TARDIEU Nicolas via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Dear PETSc users,
>
> I plan to solve nonlinear quasi-static problems with PETSc. More
> precisely, these are solid mechanics problems with elasto-plasticity.
> So they do not involve  "physical time", rather  "pseudo time", which is
> mandatory to describe the stepping of the loading application.
> In general, the loading vector F(x, t) is expressed as the following
> product  F(x, t)=F0(x)*g(t), where g is a scalar function of the
> pseudo-time.
>
> I see how to use a SNES in order to solve a certain step of the loading
> history but I wonder if a TS can be used to deal with the loading history
> through the definition of this g(t) function ?
>

I believe so. We would want you to formulate it as a differential equation,

  F(x, \dot x, t) = G(x)

which is your case is easy

  F(x, t) = 0

so you would just put your function completely into the IFunction. Since
there is no \dot x term, this is a DAE,
and you need to use one of the solvers for that.


> Furthermore, since too large load steps can lead to non-convergence, a
> stepping strategy is almost always required to restart a load step that
> failed. Does TS offer such a feature ?
>

I think you can use PETSc adaptation. There is a PID option, which might be
able to capture your behavior.

  Thanks,

      Matt


> Thank you for your answers.
> Regards,
> Nicolas
> --
> *Nicolas Tardieu*
> *Ing PhD Computational Mechanics*
> EDF - R&D Dpt ERMES
> PARIS-SACLAY, FRANCE
>
>
> Ce message et toutes les pièces jointes (ci-après le 'Message') sont
> établis à l'intention exclusive des destinataires et les informations qui y
> figurent sont strictement confidentielles. Toute utilisation de ce Message
> non conforme à sa destination, toute diffusion ou toute publication totale
> ou partielle, est interdite sauf autorisation expresse.
>
> Si vous n'êtes pas le destinataire de ce Message, il vous est interdit de
> le copier, de le faire suivre, de le divulguer ou d'en utiliser tout ou
> partie. Si vous avez reçu ce Message par erreur, merci de le supprimer de
> votre système, ainsi que toutes ses copies, et de n'en garder aucune trace
> sur quelque support que ce soit. Nous vous remercions également d'en
> avertir immédiatement l'expéditeur par retour du message.
>
> Il est impossible de garantir que les communications par messagerie
> électronique arrivent en temps utile, sont sécurisées ou dénuées de toute
> erreur ou virus.
> ____________________________________________________
>
> This message and any attachments (the 'Message') are intended solely for
> the addressees. The information contained in this Message is confidential.
> Any use of information contained in this Message not in accord with its
> purpose, any dissemination or disclosure, either whole or partial, is
> prohibited except formal approval.
>
> If you are not the addressee, you may not copy, forward, disclose or use
> any part of it. If you have received this message in error, please delete
> it and all copies from your system and notify the sender immediately by
> return message.
>
> E-mail communication cannot be guaranteed to be timely secure, error or
> virus-free.
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20221219/693a53f9/attachment.html>