version 16.4 contact

jacob

Hello, what happened with contact in version 16.4?

Why do I get this error,

L'algorithme de Newton a échoué lors de la projection du point de coordonnées ║
[1,0]<stdout>: ║ (-538.151403,-55.444273,76.281255) ║
[1,0]<stdout>: ║ sur la maille 0. ║
[1,0]<stdout>: ║ Erreur de définition de la maille ou projection difficile.

for older versions like 15.4. and 16.2 there is no problem.

Guillaume_G

Hello,

I am fighting with the same problem using 16.4 and 17 versions. I am not sure if the problem appeared in 16.4, I can not check with older versions because I need certain features from latest versions.

It is happening with QU4 elements and never with TRI3 elements. Reviewing the code, it seems that the problem occurs during the pairing procedure with continuous contact. The procedure relies on the projection of the slave node onto master elements and uses a Newton algorithm. Maybe the fact that TRI3 elements are strictly flat is making convergence easier.

Replacing in bibfor/cont_pair/mmnewt.F90 the line 159

if (type_elem .ne. 'QU4' .and. type_elem .ne. 'QU8') then

if (type_elem .ne. 'QU8') then

is improving the situation by a lot. Now it converges most of the time with QU4 elements, but still randomly crashes in some cases where nothing seems to justify it. I assume there was a reason why the part of the code considering local curvature was not activated for QU4 elements, so the modification suggested above is likely not making the subroutine 100% correct.

It would be great if someone that knows this part of the code better could suggest a change to make it possible to work with QU4 elements without random crashes.

jacob

Yes, I also found out later that tor tria as target it works for my case.
However for simple 3d beams with all hexa contact worked even for q4, for both contact and target. So it seems for planar q4 it works.

Where do I found bibfor/cont_pair/mmnewt.F90 if I have only .sif container?

Guillaume_G

jacob You would need to download the source code and compile yourself if you want to make changes

AsterO'dactyle

Hello,

We've also detected some problems recently.
It seems to be due to a change in version 16.3.1, linked to developments for the HPC version.

Guillaume_G

AsterO'dactyle Thank you. Can you indicate the exact commit where the problem was introduced ? Do you already know what would need to be changed in which file to solve the issue ?