Calculate electrical resistance - thermal transient modelling 1

[GeorgeEllwood]

Hello,
I'm trying to model a superconducting magnet quenching. This is when the temperature of the superconductor rises above a critical temperature in a zone and the electrical resistance of the conductor becomes greater than zero, heat is then generated in the resistive zone because current is flowing through it and it has a resistance. The resistive zone then increases in size due to thermal conduction and joule heating.
So far I've created a thermal transient model that can show the propagation of temperature through the model. This model uses the specific heat capacity and the thermal conductivity (both of which are functions of temperature) and after a heat pulse is added to part of the model, the temperature is then calculated.
What I would then like to do is to calculate the electrical resistance of the resistive zone using ANSYS. The electrical resistivity is a function of temperature, I've some equations/data tables that describe it. At the end of each sub-step I would like ANSYS to calculate the temperature of each element and then using the volume of the element and the resistivity data to calculate the resistance of that element. From then onwards I can then calculate the total resistance of the model. At the next time step using the resistance from the previous time step I can calculate the current drop and then go through the same process until all the current in the magnet has dissipated, whilst calculating the temperature rise and time for current to dissipate etc.
Would anyone be able to advise on how to get ANSYS to calculate the electrical resistance? I can think of a few ways to do it but they seem too clunky so I might be missing something obvious.
Any help would be greatly appreciated.
Cheers
George

 

[GeorgeEllwood]

Hello,
I think I can do what I want using element tables, the only problem I have is that I need to use a step function to calculate the resistivity, less than a certain temperature it is zero, then when it is transitioning it is a different function and then finally it is a third function. Does anyone know how I can programme this into the element table?
At anyone one point different regions of the conductor will be at different temperatures and have dramatically different resistivities so I can't use a blanket IF command outside of the table.
Any help would be greatly appreciated.
Cheers
George

 

[fuzzdoug]

does your license allow you to do a coupled thermal-electric analysis?
i use thermal-electric analysis all the time to compare lead-acid battery grids.

if you have a mechanical license, you have access to the thermal-electric analysis system.
it may give you what you are looking for.

 

[GeorgeEllwood]

Hi FuzzDoug, thanks for the reply. I've got access to coupled field licences but wanted to keep it the two environments seperate so that I could control the electrical side.
I think I've found a way to do what I wanted. I can use a DO loop to interrogate the element table of temperatures and then calculate the resistivity of each element can copy into a parameter array. I can then copy that array to an element table and then do the manipulation I want to calculate the resistance and then the heat generation.
Thanks
George