Hi all,

I have to conduct a coupled structural and heat transfer analysis. The aim is to calculate displacements in a part subjected to heat sources varying with time. So far, I've never done heat transfer analysises, so I'm looking for some expert input before I calculate rubbish.
My first question would be what elements I should use for the coupled thermal and structural analysis. The choice would be between tetra8 (eight-noded parabolic tetrahedrons) and hexa8/hexa20 (linear or parabolic bricks) elements. I did not include the tetra 4 because of its poor structural performance. The bricks promise to be the "best choice", but as far as I can see now, the geometry can't be easily mapped meshed, so this can be prohibitive for the bricks. How much should the thermal performance of the tetrahedrons be estimated to differ from the brick elements? How much does the parabolic element formulation improve the elements' performance in the thermal analysis?

Secondly, I can't guarantee to be able to create a mesh of very high quality. It may be that there will be a few elements with bad distortion values and/or high aspect ratios. I know that this will compromise the accuracy of the structural analysis. How about the thermal part? Is its the accuracy affected in the same way?

Thirdly, as implied above, I guess I have to performe a transient analysis because the heat sources vary over time at different locations. For a steady state solution, it would be easy to "split" those two analysises in a way, that first the temperature distrubution is simulated and then the displacements/stresses that result from that temperature distribution. Is there a way to equally split the two analysises in case of a transient simulation?

Any help on these topics would be highly appreciated.
Cheers,
Daniel