Thermal-electric transient problem

[lebasi]

Hi

After my first question in this forum, problems keep going with Ansys, so I have new headache, new question.. In my model, Tig welding torch, I need to set current flow ( 150 amperes). I think what I m doing is not good; I have changed specify heat and then temperatures dont change. If I change resistivity material cable, they change just a little ( for example from 330.33 to 330.34. Also graphic of electric flux density vector is very strange, without scale ..all red.
My analysis is transient and it might the load is gone, I dont know what is wrong.
I wrote this code to set the excitation:
ASEL,S, , , 392 !area cable to set my excitation
NSLA,R,1 !select node of that area
NPLOT
F,all,AMPS,i/node !set current flow, if I want 300 Amperes, divide by nodes number in that area.

Some advice will be welcome
thanks
isabel

 

[cbrn]

Hi,
1- are you sure you use element type(s) which is(are) compatible with thermo-electric coupled-field analysis?
2- are you sure the units are consistent for every input property of the material(s)? and for every boundary condition?
3- are you sure the transient duration in not too long, so that whatever you input for specific heat, conductivity, resistivity, etc, everything ends up to be at the same equilibrium temperature? Check your model with a very short duration: disuniformities should emphasize.
4- be sure you have "stepped loads" selected in the transient settings, otherwise the current intensity will be progressively ramped through all the analysis steps, giving you absurd results
5- check the concept of your analysis with a simplified model: for example, a "cube" where one face is held at constant reference temperature and the other is subjected to a thermal load
6- you say the temperatures and flux density plots are strange (I'd say "non-existing", i.e. constant, if you see them "all red"): but at which time step?

These are only some ideas... Hope it helps...

Regards