Learning Forum

[Tim Fricke]

Hey Everyone,

I have a problem with my transient thermal calculation. I have two components that are connected to each other with a contact. 

Now I apply a heat load for one second and ramped to 220°C,  to the smaller part in the middle. After that I deactivate the heatload and want to observe the cooling behavior of 16 sec.

So far so good. But If I now look at the temperature results, the maximum temperature after the heatload is deactivated continues to rise up to 343 degrees. How is this even possible?

Does anyone know how this could happen? 

Best regard 

Tim

[dlooman]

Also, there is a negative temperature which is non-physical.  This issue appears to be the result of using too small a time-step relative to the 2nd order element size.  The smallest time-step that can be used is given in Section 3.4.3.2 of the APDL Thermal Analysis Guide.  Workarounds are using a finer mesh, increasing the time step or using first order (Linear) elements.