As we have always used bricks in the past, one thing we had to watch out for when analyzing assemblies using brick elements was that the nodes between to mating parts had to line up. Sometimes this meant meshing with finer meshes or adding refinement points to get the nodes on the faces of two adjacent parts to line up.
Are the meshes of two adjacent surfaces required to match when using tetrahedral elements?
The few analyses that I ran seem to work just fine using tetraheldral elements and not having the meshes between two adjacent surfaces match.
The requirements for matching meshes are the same for brick and tet elements. What those requirements are depend on the analysis type and the type of contact. See the page "Help > Autodesk Simulation > Mesh Models > Mesh Overview > Contact Pairs > Types of Contact" for details. The table near the top of the page gives all of the different combinations.
John Holtz, P.E.
Senior User Experience Designer, Simulation
Current version of Mechanical & Multiphysics: 2013 SP1 (2013.01.00.0012 28-Jun-2012)