Irregular contact force

Good morning,

I am modeling a rotor composed by three components: shaft, magnet and surrounding fiber.

I would like to evaluate the effect of thermal expansion, simulating the contact between the three components.

I have some difficulties with contacts (the contact force is not constant, as expected). Differences are quite small, but I would like to ask you if there are any errors in my model or if there are any possibilities to obtain better results (I have already tried with s2s option in contact definition and with expertnl param).

Thank you so much for your kindness

Enrico