Greetings,
I have a model of a nozzle in a cylinder 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.
check if you have same issue using solver pardiso or spooles instead of pastix
Often it doesn’t converge when there’s no load, so a very small load might be the same.
I think that for that special cases the controls card needs adjustments
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