Thermal expansion in a core wire

Hello, We are trying to simulate the thermal expansion of a guide wire from the medical industry, when it is exposed to 4 different temperatures in 4 different ovens. We are using the solid mechanics module, add the thermal expansion node to add the reference temperature and the temperature in the oven, and the initial stress and strain node. Also we used 4 different physics of solid mechanics to model the 4 ovens. The initial stress and strain node was used to stablish the initial strain and stress of the second oven due to the first one and so on.
However, We are having problems to define the boundary conditions to model this problem, and we are not sure if the model it´s well define. We are pretty new at comsol. Can you help us please?