Hello!
I'm new in Comsol and trying to create a simplified track model in 2D, where I'm applying load on the top (of the sleeper). The model has 5 layers: sleeper, ballast, asphalt, sub-ballast, and subgrade. On the top and bottom of the asphalt layer, I want to put a contact pair with friction applied. But it is only possible to compute when the side of the layers have fixed boundary conditions. But there should not be any fixed BC for the first 4 layers, as there is nothing like that in reality (nothing on the sides of the structure), except for the bottom layer. When I try to compute without fixed BC on the top 4 layers, it doesn't compute (getting errors) because of incorrect BC. Do you have any ideas on how to fix this, what kind of BC (that aren't fixed) can I apply, so it will work in my case? The link to the model (Comsol 5.5) is: https://www.dropbox.com/s/d9p5sxextfik61w/NEW_MODEL.mph?dl=0 Thank you in advance!
Kind regards, Aleksandra