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## Main Question or Discussion Point

So I am doing a FEA simulation on Joule heating of a busbar and consequently its thermal expansion. So the idea is that if I only use 1 study step, and have the temperature output from the joule heating as an input for thermal expansion, COMSOL calls this as a weakly coupled system, and they don't like it.

Instead, they recommend breaking down the study into 2 steps, the first step to just calculate the joule heating, and the second step just calculate the thermal expansion. The input is still the same.

Personally I feel like nothing mattered, it's just like instead of achieving 1, we choose to do 0.5 + 0.5. I tried both ways, and the answer does not change much from one another. I tried to google the definitions of weakly and strongly coupled systems, and couldn't find any for some reason. So maybe you could explain it to me?

here is the excerpt from the manual I am working from:

"The Joule heating effect is independent of the stresses and strains in the busbar, assuming small deformations and ignoring the effects of electric contact pressure. This means that you can run the simulation using the temperature as input to the structural analysis. In other words, the extended multiphysics problem is weakly coupled. As such, you can solve it in two separate study steps—one for the strongly coupled Joule heating problem and a second one for the structural analysis."

Instead, they recommend breaking down the study into 2 steps, the first step to just calculate the joule heating, and the second step just calculate the thermal expansion. The input is still the same.

Personally I feel like nothing mattered, it's just like instead of achieving 1, we choose to do 0.5 + 0.5. I tried both ways, and the answer does not change much from one another. I tried to google the definitions of weakly and strongly coupled systems, and couldn't find any for some reason. So maybe you could explain it to me?

here is the excerpt from the manual I am working from:

"The Joule heating effect is independent of the stresses and strains in the busbar, assuming small deformations and ignoring the effects of electric contact pressure. This means that you can run the simulation using the temperature as input to the structural analysis. In other words, the extended multiphysics problem is weakly coupled. As such, you can solve it in two separate study steps—one for the strongly coupled Joule heating problem and a second one for the structural analysis."