Discussion Forum

David,

there had recently been a couple of posts about helices with certain cross sections. I would recommend to search the forum. Your picture shows something that goes far beyond a helix.

Cheers
Edgar

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Edgar J. Kaiser
emPhys Physical Technology

Hi Edgar,

I did see a few related posts before I wrote mine -- they seem to seek different things, however.

Perhaps I shouldn't have used the term cross-section. I'm happy with the wire being circular. I want the shape into which it's *wrapped* to be non-circular. So really, I don't want a helix so much as I want a spiralling shape -- the kind of shape you get when wrapping wire around an arbitrarily-shaped former.

Do you have any ideas on how to achieve this? I suspect it might be wise to use another package to make the model, then import this into COMSOL for the simulation phase.

David,

you could try to find a suitable parameterization of the wire trajectory of your coil and then sweep a circular cross section (the wire) along this trajectory.
You would probably have to do something similar in any CAD software too, wouldn't you? It is in general better to generate the geometry in COMSOL rather than importing it. Importing may be an advantage in case the geoemtry already exists in a CAD format.
Explicitely modeling a coil as the one you showed in the picture will result in a huge mesh and respective memory requirements.

Can you approximate the coil by a multiturn coil domain?

Cheers
Edgar

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Edgar J. Kaiser
emPhys Physical Technology

Hi Edgar,

I did attempt to model the coil by sweeping through a parametric curve. Unfortunately, I was unable to find a curve that was easily meshable and computationally affordable. This could have been because I mostly limited myself to considering variants on the superellipse. Do you have any other ideas for parametrised shapes I might try?

I looked into the multi-turn coil domain when I began this project. As I understand it, the multi-turn coil domain is useful for electromagnetic properties, but does not give turn-by-turn simulation of mechanical properties. Please, though, correct me if I am mistaken --in this case, it would be wonderful to find that I am wrong!

Ok, I realize, that it is all about mechanics. Well, regardless of the parameterization you will end up with cross sections of many circles touching each other. This is always difficult to mesh.
What mechanical properties exactly are you after? Is the coil a loose bunch of windings or is it embedded into a resin matrix? Do you need to resolve the wire structure or can you approximate by a solid body?

If you really need to explicitely resolve the wires, can you start with a 2D axially symmetric model and look how it behaves?

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Edgar J. Kaiser
emPhys Physical Technology

Good point RE meshing.

I am interested in tryino get thermally induced stress and strain on a wire by wire basis. I am interested in motors with and without resin.

I have managed something like a 2D simulation. This is my attempt to extend it.