I’m very much obliged to you if you would be so kinds help me. I am trying to design washing machine. Initially I want to try doing a static analysis. For this, I have modeled cylinder (shell) and, placing them on the solid ribs. After this i have applied boundary condition to the assembly, and also a load (centrifugal). For only Tie connection between cylinder and rib, I got simulation but less strain at rib region. I want more stiffness at connecting rib, that’s I am going to contact analysis.I am doing shell tria3 to solid tetra4.I have defined an interaction (Surface-to Surface) between the cylinder and the rib with Normal Contact condition. I am getting an error saying 1)" The slave surface nodes are penetrating the Master surface” 2) The system matrix has negative eigenvalues. 3) Model is not working Can suggest a solution to this problem and if possible say whether i will get what i am expecting after doing all this. Thanks a lot in advance...Regards