Indeed, this is exactly how we do quasistatic analysis for solid mechanics in Ratel (https://gitlab.com/micromorph/ratel) -- make sure to choose an L-stable integrator (backward Euler being the most natural choice). Implicit dynamics can be done by choosing a suitable integrator, like TSALPHA2, with almost no code change to the residual (only adding the mass term in DMTSSetI2Function()).
Matthew Knepley <knep...@gmail.com> writes: > On Mon, Dec 19, 2022 at 6:12 AM TARDIEU Nicolas via petsc-users < > petsc-users@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/>
