Elmer Discussion Forum

I downloaded both meshes and the sif file. I turned on the paraview post processing file to view the deformations in the coarse mesh and there appeared to be an issue. The two vertical wires are not full constrained in 3D space therefore they start moving unconstrained, once impacted with a force. Note that dynamics are on, this is not just a static analysis by default. Once the unrestrained wires are loaded acceleration will occur and they will start moving in space unrestrained, and unrestrained motion results in large deflections.

I modified the sif to restrain all four wires form rigid body motion and both the coarse and fine mesh solves without issue.

I don't think this is a contact surface issue.

Hi Maike

I'm afraid there is not much news. I did add a way to compute a mortar projector for generic geometries. It is used in test case "RotatingBCPoisson3DNT". The idea is to go trough the slave elements and use local normal-tangential coordinate system for the candidate master elements. The initial distance is used to make the rough cut.

The good news is that the generic projector seems to work. The bad news is that for contact mechanics it would probably require some modifications. I did not get it to work out-of the box. You can of course try to play a little with it but I think some coding may be required.

-Peter

Hi Kevin,

thank you for your effort and time. I got my case running by re-meshing and slightly altering the parameters in Salome (e.g. max element size 0.031 instead of 0.03). Which was tiring, because sometimes I had to re-mesh 10 times until it finally worked.

I also did biaxial tensile tests, where I pull both the vertical and horizontal wires, e.g. in y- respectively x- direction and prohibit the displacement of the other ends of the wires in every direction (I attached a picture). This means there should not be any unrestrained movements. I encountered the same problems. In fact there were even cases when I finally found a mesh that worked for the uniaxial case, but that did not work for the biaxial case. Or even cases when a mesh worked for the x,y-biaxial pull but did not for a e.g. -x,-y-biaxial pull.

Sincerely
Maike

Hi Peter,

thank you for your answer. Unfortunately I don't think I will find the time to get into coding.

But if someday somebody manages to make the projector work for contact I'd be happy to get back to Elmer!

Sincerely
Maike

HI Maike,

What's your schedule? There is more time for coding now as all meetings are cancelled due to the virus. I might have a 2nd look some day.

-Peter

Hi Peter,

this project has been put on hold and I now have to work on other projects. And despite of the situation I still have to go to work

So it would be nice if you'd find the time but there is no rush.

Sincerely
Maike