Menu

Discussion Forum

New Discussion
Filtrer

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Electrical resistance in a structure

Posted 11 mars 2013, 07:39 UTC−4 Low-Frequency Electromagnetics, Structural Mechanics Version 4.3 11 Replies

Ehsan Rezaei
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

hello everybody,
I need to have a simulation of electrical potential in 1D beam elements in a structure. I want to give potential to one point of the model and ground to another point and observe the current flow inside the beam. in fact I need to calculate the whole electrical resistance inthe structure.
when I use Electrical Current in AC/DC module, it tells me that it is not applicable to select a point as a "point electric potential" or "point ground".
I have attached a picture of a sample structure.
How can I do this. should I use another module?

Thanks in advance
Ehsan

Attachments:

11 Replies Last Post 18 mars 2013, 06:38 UTC−4
Ehsan Rezaei
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 14 mars 2013, 10:03 UTC−4
plz, does anybody knows about this?
plz, does anybody knows about this?
Edgar Kaiser
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 14 mars 2013, 10:43 UTC−4

I am wondering if it makes sense to implement this in a COMSOL model or any FE model in general.

Do you have any interaction of the currents in the wire with the geometry in mind? Are the wires interacting by electric or magnetic fields? Is the resistance of the wires affected by their arrangement? And how do you specify the resistivity of the wires?

If it is just about static resistance within this network you could represent the wires by resistors proportional to their length in a circuit simulator like LT Spice.

Cheers
Edgar
I am wondering if it makes sense to implement this in a COMSOL model or any FE model in general. Do you have any interaction of the currents in the wire with the geometry in mind? Are the wires interacting by electric or magnetic fields? Is the resistance of the wires affected by their arrangement? And how do you specify the resistivity of the wires? If it is just about static resistance within this network you could represent the wires by resistors proportional to their length in a circuit simulator like LT Spice. Cheers Edgar
Ehsan Rezaei
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 14 mars 2013, 10:56 UTC−4
Thanks Edgar for your kind answer,
actually the structure will go undet tension and I want to see the electrical resistance change during the tensile loading. thats the reason to do it in comsol.
two side of the structure are connected to a power supply and by loading the current changes in each section.
the structure is not made of wires, it is a cellular material so based on their diameter they have a specific resistance.

Thanks again,
Ehsan
Thanks Edgar for your kind answer, actually the structure will go undet tension and I want to see the electrical resistance change during the tensile loading. thats the reason to do it in comsol. two side of the structure are connected to a power supply and by loading the current changes in each section. the structure is not made of wires, it is a cellular material so based on their diameter they have a specific resistance. Thanks again, Ehsan
Edgar Kaiser
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 14 mars 2013, 12:00 UTC−4
Ehsan,

then you must implement the structure as physical domains, e.g. thin cylinders. The cylinder ends can be defined with a terminal BC and you can connect the terminals to a circuit physics node and measure impedances.

Cheers
Edgar
Ehsan, then you must implement the structure as physical domains, e.g. thin cylinders. The cylinder ends can be defined with a terminal BC and you can connect the terminals to a circuit physics node and measure impedances. Cheers Edgar
Ehsan Rezaei
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 14 mars 2013, 12:07 UTC−4
Dear Edgar,
do you mean using 3d elements? or I got it wrong.
I have touse 1D element(so just lines) because the model is huge and it will be very expensive to model it in 3D.

to use terminals as you said I have to use AC/DC lectrical circuit module?(I'm beginner in COMSOL, specially for electrical simulations)

thanks again
Ehsan
Dear Edgar, do you mean using 3d elements? or I got it wrong. I have touse 1D element(so just lines) because the model is huge and it will be very expensive to model it in 3D. to use terminals as you said I have to use AC/DC lectrical circuit module?(I'm beginner in COMSOL, specially for electrical simulations) thanks again Ehsan
Edgar Kaiser
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 14 mars 2013, 12:16 UTC−4

I think you can't do it with lines in a 3D model.

And yes, you can use the AC/DC circuit physics together with electrical currents.

Cheers
Edgar
I think you can't do it with lines in a 3D model. And yes, you can use the AC/DC circuit physics together with electrical currents. Cheers Edgar
Ehsan Rezaei
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 14 mars 2013, 13:56 UTC−4
Thanks Edgar for all your help :)

Saluti,
Ehsan
Thanks Edgar for all your help :) Saluti, Ehsan
Sven Friedel COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 15 mars 2013, 04:57 UTC−4
Hi Ehsan (and Edgar),

as there is hardly anything that can't be done in COMSOL there is also a solution for edge currents in 3D.

You can very easily use the coefficient form on edges to model that. The attached model shows a wire cube
(the kind that electrical engineering students at my study time needed to solder in their base practicals).

Two corners are connected to ground and a potential. The picture shows the potential and the current density.
For symmetry reasons one branch is completely current free.

If you want to wrap that equation into a physics interface you can also do that using the physics interface builder.

Best regards,
Sven
Hi Ehsan (and Edgar), as there is hardly anything that can't be done in COMSOL there is also a solution for edge currents in 3D. You can very easily use the coefficient form on edges to model that. The attached model shows a wire cube (the kind that electrical engineering students at my study time needed to solder in their base practicals). Two corners are connected to ground and a potential. The picture shows the potential and the current density. For symmetry reasons one branch is completely current free. If you want to wrap that equation into a physics interface you can also do that using the physics interface builder. Best regards, Sven
Sven Friedel COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 15 mars 2013, 04:58 UTC−4
correction: two edges are current free
correction: two edges are current free
Edgar Kaiser
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 15 mars 2013, 08:11 UTC−4
Hi Sven,

that's amazing, thank you for this one! I might as well have applications for that. I will really need to have a deeper look into the PDE interface. And you are right: saying "you can't do that" in COMSOL may sometimes be correct regarding a specific application module but mostly not in the context of complete COMSOL.

Cheers
Edgar
Hi Sven, that's amazing, thank you for this one! I might as well have applications for that. I will really need to have a deeper look into the PDE interface. And you are right: saying "you can't do that" in COMSOL may sometimes be correct regarding a specific application module but mostly not in the context of complete COMSOL. Cheers Edgar
Ehsan Rezaei
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 18 mars 2013, 06:38 UTC−4
Dear Sven,
Thanks a lot for the model you sent. It solved my problem :)
Dear Sven, Thanks a lot for the model you sent. It solved my problem :)

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content