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How to fully couple thermal expansion displacement with heat transfer?

Posted 03.06.2021, 14:38 GMT-4 2 Replies

Tianyu Yang
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Dear COMSOL community,

I am trying to use solid mechanics (thermal expansion) and heat transfer to investigat how the displacement from thermal expansion affects the heat transfer in turn. I tried with fully-coupled solver but the heat transfer is still not affected by the thermal expansion. Would you give some pieces of advice about this issue? I really appreciate it.

Thank you, Tianyu

2 Replies Last Post 08.06.2021, 16:29 GMT-4
Alex Krstic
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Posted: 3 years ago 03.06.2021, 15:12 GMT-4

I am having the same issue when trying to model a joule-heating thermally actuated microgripper. The file "thermal_actuator_tem_parameterized" in the application library has one-way coupling in a thermal actuator and the file "thermal_actuator_simplified" shows how to fully couple the deformation and heat transfer using the equation view. Have you tried following the PDF guide for these models? I have attached them below in case you do did not find them.

If anyone could shed some light on this topic that would be greatly appreciated. Currently the thermal microgripper that I am modelling with both one-way and two-way coupling is greatly overheating in the hot arms which does not correspond with the real-world prototype that was already lab tested. Any help or advice would be greatly appreciated!

  • Alex
I am having the same issue when trying to model a joule-heating thermally actuated microgripper. The file "thermal_actuator_tem_parameterized" in the application library has one-way coupling in a thermal actuator and the file "thermal_actuator_simplified" shows how to fully couple the deformation and heat transfer using the equation view. Have you tried following the PDF guide for these models? I have attached them below in case you do did not find them. If anyone could shed some light on this topic that would be greatly appreciated. Currently the thermal microgripper that I am modelling with both one-way and two-way coupling is greatly overheating in the hot arms which does not correspond with the real-world prototype that was already lab tested. Any help or advice would be greatly appreciated! - Alex
Tianyu Yang
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Posted: 3 years ago 08.06.2021, 16:29 GMT-4

Thank you, Alex. It is very helpful. I checked your models and mine. When I include the geometry nonlinearity in my solver, it can not converge any more. I think that the large deformation (more than 50%) causes some troubles to the solver. I am trying to figure it out. Do you have some advice for this issue? I am thinking about adding "deformed geometry" interface to my model.

For your model, the overheating problem reminds me of the convection heat transfer coefficient. Did you check that the HTC is realistic? The electrical resistivity also depends on the temperature, where the positive feedback to heat generation could make the hot arm hotter. I would double check whether the electrical resistivity as a function of temperature matches experimental materials or not.

Thanks, Tianyu

Thank you, Alex. It is very helpful. I checked your models and mine. When I include the geometry nonlinearity in my solver, it can not converge any more. I think that the large deformation (more than 50%) causes some troubles to the solver. I am trying to figure it out. Do you have some advice for this issue? I am thinking about adding "deformed geometry" interface to my model. For your model, the overheating problem reminds me of the convection heat transfer coefficient. Did you check that the HTC is realistic? The electrical resistivity also depends on the temperature, where the positive feedback to heat generation could make the hot arm hotter. I would double check whether the electrical resistivity as a function of temperature matches experimental materials or not. Thanks, Tianyu

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