Hi ArraynYour suggestion did not help. nHowever, I somehow came to check the element type that I am using. I've never defined to use shell181 elements because I thought that it was the default shell element. The only commands I had used before in the preprocessor were:nnKEYOPT,1,1,0nSECTYPE,1,SHELLnSECDATA,12,,,15nnNow I've added: ET,matid,181nAnd my simulation finally works. Now I am really curious about what is the default shell element? I can't find it anywhere unfortunately, maybe it is somewhere in the files on my PC?. I always thought that the default was shell181 whenever you create a flat geometry with a certain thickness.. Hopefully you can give me answer to this.nKind regards,nJoost