# Convergence issue with small load **URL:** \ **Category:** Uncategorized\ **Created:** [May 9, 2025, 4:17pm UTC](https://calculix.discourse.group/t/convergence-issue-with-small-load/2737 "2025-05-09T16:17:34Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![kraviteja](https://avatars.discourse-cdn.com/v4/letter/k/bbe5ce/32.png) [@kraviteja](https://calculix.discourse.group/u/kraviteja)\ **Post date:** [May 9, 2025, 4:17pm UTC](https://calculix.discourse.group/t/convergence-issue-with-small-load/2737/1 "2025-05-09T16:17:34Z")
Greetings, I have a [model of a nozzle in a cylinder](https://www.dropbox.com/scl/fo/eu4snmxf71jdjphbr0lfh/ACcZK8CXvmGH-2o-GeE-lm4?rlkey=dy0ga9vcj7g6ynsmlv37ndlnq&st=62jj1tt5&dl=0) and I am having convergence problems when I run the model in ccx2.20 with an elastic-plastic material model and NLGEOM=YES. It is strange because the load is so small. The model converges when I use a larger force or when I use an elastic model. It even converges when I set the initial step to 0.1001 instead of 0.1. I’ve also attached the log file from my run. Can someone please help me understand what is going wrong here. ---
**Author:** ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74)\ **Post date:** [May 9, 2025, 6:04pm UTC](https://calculix.discourse.group/t/convergence-issue-with-small-load/2737/2 "2025-05-09T18:04:35Z")
check if you have same issue using solver pardiso or spooles instead of pastix ---
**Author:** ![vicmw](https://avatars.discourse-cdn.com/v4/letter/v/6de8d8/32.png) [@vicmw](https://calculix.discourse.group/u/vicmw)\ **Post date:** [May 10, 2025, 7:07pm UTC](https://calculix.discourse.group/t/convergence-issue-with-small-load/2737/3 "2025-05-10T19:07:04Z")
Often it doesn’t converge when there’s no load, so a very small load might be the same. ---
**Author:** ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74)\ **Post date:** [May 10, 2025, 8:44pm UTC](https://calculix.discourse.group/t/convergence-issue-with-small-load/2737/4 "2025-05-10T20:44:12Z")
I think that for that special cases the controls card needs adjustments ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 12, 2025, 11:46am UTC](https://calculix.discourse.group/t/convergence-issue-with-small-load/2737/6 "2025-05-12T11:46:14Z")
Now I understand better your problem. The issue is due to the initial time step. I did not read carefully your explanation sorry. This is the .sta results for decreassing initial time steps. \*Step, Nlgeom, Inc=300 \*Static, Solver=Pardiso **0.25** , 1., 1E-05, 1. SUMMARY OF JOB INFORMATION STEP INC ATT ITRS TOT TIME STEP TIME INC TIME 1 1 1 2 **0.250000E+00 0.250000E+00** 0.250000E+00 1 2 1 2 0.500000E+00 0.500000E+00 0.250000E+00 1 3 1 2 0.875000E+00 0.875000E+00 0.375000E+00 1 4 1 2 0.100000E+01 0.100000E+01 0.125000E+00 \*Step, Nlgeom, Inc=300 \*Static, Solver=Pardiso **0.15** , 1., 1E-05, 1. SUMMARY OF JOB INFORMATION STEP INC ATT ITRS TOT TIME STEP TIME INC TIME 1 1 1 2 **0.150000E+00 0.150000E+00** 0.150000E+00 1 2 1 2 0.300000E+00 0.300000E+00 0.150000E+00 1 3 1 2 0.525000E+00 0.525000E+00 0.225000E+00 1 4 1 2 0.862500E+00 0.862500E+00 0.337500E+00 1 5 1 2 0.100000E+01 0.100000E+01 0.137500E+00 \*Step, Nlgeom, Inc=300 \*Static, Solver=Pardiso **0.10** , 1., 1E-05, 1. SUMMARY OF JOB INFORMATION STEP INC ATT ITRS TOT TIME STEP TIME INC TIME 1 1 1U 9 **0.000000E+00 0.000000E+00** 0.100000E+00 1 1 2 3 0.250000E-01 0.250000E-01 0.250000E-01 1 2 1 2 0.500000E-01 0.500000E-01 0.250000E-01 1 3 1 4 0.875000E-01 0.875000E-01 0.375000E-01 1 4 1U 6 0.875000E-01 0.875000E-01 0.562500E-01 1 4 2U 4 0.875000E-01 0.875000E-01 0.140625E-01 1 4 3U 4 0.875000E-01 0.875000E-01 0.351563E-02 1 4 4 3 0.883789E-01 0.883789E-01 0.878906E-03 1 5 1U 7 0.883789E-01 0.883789E-01 0.878906E-03 1 5 2U 4 0.883789E-01 0.883789E-01 0.219727E-03 1 5 3U 6 0.883789E-01 0.883789E-01 0.549316E-04 1 5 4U 6 0.883789E-01 0.883789E-01 0.137329E-04 First two end properly. Last one (0.1) fails to converge. Curiosuly the initial step time is 0