problems with an easy heat model

hello,

I am starting to use Comsol and I have a problem with an easy model.

I have a heat source, that have modelled as a box of copper, and a thin shell of aluminium with an small defect. I want to see the different temperatures on the shell close to the defect. The heat function is modelled with a piecewise, it turns on for 15 seconds and then it is turned off.

The problem is that when the source turns off, it remains at the same temperature and the shells is not heated.

I can´t attach the model because of it´s size.


Thank you