Thank youpeteroznewman nAbout the static analysis i agree with you, it should decrease a lot the computation time. I just need the transient module for a further analysis i'll have to perform if, after heating up, i apply a displacement on the steel part in order to remove that from the contact with the aluminum (for this reason i need also the frictional contact).nStill, i don't know which condition can i implement to the external surface of the aluminum. As you said it's like a large amount of aluminum is around the steel tube. I was wondering if there is a way to apply a spring for each node of the external surface, which has the same stiffness of the aluminum. I have tried the elastic support, but the stiffness is unknown and i think that ansys can compute it. For this reason i think that symmetry could fit with my problem. I tried symmetry but a simmetry normal is requested. n