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Modelling Contact During Thermal Expansion

Modelling Contact During Thermal Expansion

Modelling Contact During Thermal Expansion

(OP)
Hi All,

I am trying to model the stress and heat transfer in a model of a Thermoelectric Generator (TEG) device.

The device contains an inner heat exchanging fin assembly through which a hot exhaust gas will flow. This is modelled using a surface heat flux into the fins. The heat then travels through a shunt portion and into the copper tabs and thermoelectric elements which will produce electricity. Abaqus not model thermoelectric effects, but I do not want it to in this case as I am only interested in the stresses and heat transfer/temperature. The outer tab is kept cool by a boundary condition. I've attached one of my simplest models, with a coarse mess. I modelled contact between parts using Tie Constraints.

Model: http://files.engineering.com/getfile.aspx?folder=e...
/jnl: http://files.engineering.com/getfile.aspx?folder=a...

The main issue I am having is that the stresses are very high (1-12GPa in most parts of the model). I wasn't able to upload a .odb file, i am sorry.


I have gone to a very fine mesh (0.2mm elements) and still received similar stress magnitudes, although the distribution was more realistic. Still, the stresses are very high, which leads me to suspect that the Tie Constraint does not accurately model the contact and is causing very high stresses for some reason. However, whenever I try to run the model using surface-surface contact, I get errors (normally a "Displacement increment for contact is too big" error).

I am looking for help with 3 main things:
1. Are these stresses unnaturally high, and if so, is it likely caused by a contact problem?
2. Why do I get errors when running surface-to-surface contact?
3. What, in your opinion, is the best way to model the interface between these materials?

I hope I covered everything relevant, please let me know if there is any other relevant information that you need. Also, I am relatively new to Abaqus.

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