I'm currently a masters student in nuclear engineering, as part of my thesis, I have been trying to develop a simplified mechanical model of nuclear-reactor-fuel at the pellet level with COMSOL finite-element platform. (CANDU fuel for anyone who is interested) I've run into a problem when trying to use contact pairs to model the pellet-sheath contact. While I've had success with other contact pairs in other COMSOL geometries I can't seem to get it to work in this case. The contact pairs pass through each other with zero resistance and no error message. Does anyone here have any experience with contact modeling in COMSOL? Anyone know how to fix this issue? I've spent approximately two weeks working on this problem and I'm not really any closer to a solution. Basically, I have two files, one where contact works, and one where it fails but I don't know why. PF won't let me upload the files because they are an un-recognized file type on this forum, but I've posted them on the COMSOL discussion forum along with more details about my problem. http://www.comsol.com/community/forums/general/thread/8623/ If anyone is interested in looking the files but can't get them from the COMSOL site, let me know and I'll find somewhere to host them. If anyone has any ideas please share! I'm just about at my wits-end trying to get this thing to work.