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Plasticity should not cause any major difficulties with your global
iterations. Your residuals look your load steps are elastic all
the way until it fails. Are you sure that your applied boundary
conditions have a unique solutions? In particular, are you applying
forces to a perfect plasticity problem that are leading to gross
plastic flow? Perhaps try applying driving displacement boundary
conditions.<br>
-sg<br>
<br>
<div class="moz-cite-prefix">On 7/5/17 9:24 AM, Maximilian Hartig
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CABO2ERRtn-ZDNaMEyADEhKuMYX_ZT0mVPmnhOOBLrEKqHLsrdw@mail.gmail.com">
<div dir="ltr">
<div>
<div>The solver goes on for some timesteps, then it gets hung
up in step 10. The output is as follows:<br>
<br>
28 SNES Function norm 7.825649542035e-06 <br>
0 KSP preconditioned resid norm 5.335581451751e+00
true resid norm 7.825649542035e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 3.875747966342e-13
true resid norm 3.082821236889e-15 ||r(i)||/||b||
3.939380648635e-10<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
29 SNES Function norm 7.825641650401e-06 <br>
0 KSP preconditioned resid norm 5.335568660325e+00
true resid norm 7.825641650401e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 1.169064646930e-13
true resid norm 2.949237553452e-15 ||r(i)||/||b||
3.768684646199e-10<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
30 SNES Function norm 7.825633758775e-06 <br>
0 KSP preconditioned resid norm 5.335575714181e+00
true resid norm 7.825633758775e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 3.626528075820e-13
true resid norm 7.454935467844e-16 ||r(i)||/||b||
9.526302530432e-11<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
31 SNES Function norm 7.825625867144e-06 <br>
0 KSP preconditioned resid norm 5.335574289757e+00
true resid norm 7.825625867144e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 1.220021201426e-13
true resid norm 6.140701297052e-16 ||r(i)||/||b||
7.846913973787e-11<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
32 SNES Function norm 7.825617975525e-06 <br>
0 KSP preconditioned resid norm 5.335556211708e+00
true resid norm 7.825617975525e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 3.238615954344e-14
true resid norm 1.639170816829e-15 ||r(i)||/||b||
2.094621564655e-10<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
33 SNES Function norm 7.825610083913e-06 <br>
0 KSP preconditioned resid norm 5.335545135100e+00
true resid norm 7.825610083913e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 8.328043430360e-14
true resid norm 7.902728010647e-16 ||r(i)||/||b||
1.009854557780e-10<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
34 SNES Function norm 7.825609294752e-06 <br>
0 KSP preconditioned resid norm 5.335519330054e+00
true resid norm 7.825609294752e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 1.176339150741e-13
true resid norm 2.137240765649e-15 ||r(i)||/||b||
2.731085446703e-10<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
35 SNES Function norm 7.825608505592e-06 <br>
0 KSP preconditioned resid norm 5.335552250936e+00
true resid norm 7.825608505592e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 2.388837462586e-13
true resid norm 3.899327292367e-16 ||r(i)||/||b||
4.982778386601e-11<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
36 SNES Function norm 7.825607716432e-06 <br>
0 KSP preconditioned resid norm 1.017554264638e-01
true resid norm 7.825607716432e-06 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 2.758703070887e-14
true resid norm 1.990491888342e-16 ||r(i)||/||b||
2.543562059932e-11<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
37 SNES Function norm 3.815837655573e-08 <br>
0 KSP preconditioned resid norm 7.197730150406e+00
true resid norm 3.815837655573e-08 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 7.114599045039e-12
true resid norm 4.763264085142e-16 ||r(i)||/||b||
1.248287929175e-08<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
38 SNES Function norm 3.790245121284e-08 <br>
0 KSP preconditioned resid norm 7.127517791828e+00
true resid norm 3.790245121284e-08 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 2.500976336448e-11
true resid norm 1.692661771456e-15 ||r(i)||/||b||
4.465837214461e-08<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
39 SNES Function norm 3.758101652998e-08 <br>
0 KSP preconditioned resid norm 1.931834799209e-02
true resid norm 3.758101652998e-08 ||r(i)||/||b||
1.000000000000e+00<br>
1 KSP preconditioned resid norm 5.958979968059e-16
true resid norm 2.588244438237e-18 ||r(i)||/||b||
6.887105983875e-11<br>
Linear solve converged due to CONVERGED_RTOL iterations
1<br>
Nonlinear solve did not converge due to
DIVERGED_FUNCTION_COUNT iterations 39<br>
[0]PETSC ERROR: --------------------- Error Message
--------------------------------------------------------------<br>
[0]PETSC ERROR: <br>
[0]PETSC ERROR: TSStep has failed due to
DIVERGED_NONLINEAR_SOLVE, increase -ts_max_snes_failures or
make negative to attempt recovery<br>
[0]PETSC ERROR: See <a
href="http://www.mcs.anl.gov/petsc/documentation/faq.html"
moz-do-not-send="true">http://www.mcs.anl.gov/petsc/documentation/faq.html</a>
for trouble shooting.<br>
[0]PETSC ERROR: Petsc Development GIT revision:
v3.7.5-3342-gb122798 GIT Date: 2017-03-22 17:42:51 -0500<br>
[0]PETSC ERROR: ./miniFEM on a arch-linux2-c-debug named
iket127138 by hartig Wed Jul 5 18:09:53 2017<br>
[0]PETSC ERROR: Configure options
PETSC_ARCH=arch-linux2-c-debug --with-cc=mpigcc
--with-cxx=mpicxx --with-fc=mpif90 --download-ml
--download-parmetis --download-metis --download-hypre
--download-mumps --download-scalapack<br>
[0]PETSC ERROR: #1 TSStep() line 3818 in
/home/hartig/petsc/src/ts/interface/ts.c<br>
[0]PETSC ERROR: #2 TSSolve() line 4054 in
/home/hartig/petsc/src/ts/interface/ts.c<br>
[0]PETSC ERROR: #3 main() line 1829 in
/home/hartig/Nextcloud/Dissertation/Code/Debugging/miniFEM.c<br>
[0]PETSC ERROR: PETSc Option Table entries:<br>
[0]PETSC ERROR: -def_petscspace_order 2<br>
[0]PETSC ERROR: -eplast_petscspace_order 2<br>
[0]PETSC ERROR: -ksp_converged_reason<br>
[0]PETSC ERROR: -ksp_monitor_true_residual<br>
[0]PETSC ERROR: -pc_type lu<br>
[0]PETSC ERROR: -plast<br>
[0]PETSC ERROR: -snes_converged_reason<br>
[0]PETSC ERROR: -snes_fd<br>
[0]PETSC ERROR: -snes_monitor<br>
[0]PETSC ERROR: -snes_type newtonls<br>
[0]PETSC ERROR: -ts_monitor<br>
[0]PETSC ERROR: -vel_petscspace_order 2<br>
[0]PETSC ERROR: ----------------End of Error Message
-------send entire error message to
<a class="moz-txt-link-abbreviated" href="mailto:petsc-maint@mcs.anl.gov">petsc-maint@mcs.anl.gov</a>----------<br>
<br>
</div>
<div><br>
</div>
Thanks,<br>
</div>
Max<br>
<div>
<div><br>
</div>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2017-06-30 17:14 GMT+02:00 Barry Smith
<span dir="ltr"><<a href="mailto:bsmith@mcs.anl.gov"
target="_blank" moz-do-not-send="true">bsmith@mcs.anl.gov</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
What is the output from<br>
<br>
-snes_monitor -ksp_monitor_true_residual -pc_type lu
-ksp_converged_reason -snes_converged_reason<br>
<div class="HOEnZb">
<div class="h5"><br>
<br>
> On Jun 30, 2017, at 3:45 AM, Maximilian Hartig <<a
href="mailto:imilian.hartig@gmail.com"
moz-do-not-send="true">imilian.hartig@gmail.com</a>>
wrote:<br>
><br>
> Hello,<br>
><br>
> I’m trying to implement plasticity and have
problems getting the Petsc SNES to converge. To check if
my residual formulation is correct I tried running with
-snes_fd for an easy example as the Petsc FAQ suggest. I
cannot seem to get the solver to converge at any cost.<br>
> I already tried to impose bounds on the solution
and moved to vinewtonrsls as a nonlinear solver. I
checked and rechecked my residuals but I do not find an
error there. I now have the suspicion that the -snes_fd
option is not made for handling residuals who’s first
derivatives are not continuous (e.g. have an “if”
condition in them for the plasticity/ flow-condition).
Can you confirm my suspicion? And is there another way
to test my residual formulation separate from my
hand-coded jacobian?<br>
><br>
><br>
> Thanks,<br>
> Max<br>
<br>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</blockquote>
<br>
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