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## Assembled Sweeps

Hi, I have been creating sweeps of a small rectangular sketch attached to a spiral trajectory. I am trying to create a bimetallic coil, like the one in the photo below. I wish to model it in Ansys. However, to do this there needs to be two different materials (i.e. red and blue in the below photo are separate materials, and therefore separate objects).

My problem is that I have created the two spiral sweeps, and I'm having difficulty creating an assembly of the two joined together. They tend to overlap at the very center, and are constantly at 'partially constrained' status.

If anyone could help I would be very very grateful. The only constraints are that the entire assembly must fit into an envelope size of 50mm x 20mm x 15mm, so i left my outer spiral sweep with an outer diameter of 20mm. And that each material must be no less than 0.5mm thick. Thanks!
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## Re: Assembled Sweeps

FYI for others, the posted models are educational version and can not be opened with a commercial license.

I would propose you do this using the following technique.

Use curve from equation to create a logarithmic spiral base curve. This curve would represent a curve that lies on the shared surface of the two "coils" as they are wound together as shown in your pictures. You can use this base curve to create both the red and blue coils as sweeps and then assemble each of them to a single assembly using the default constraint. Sweep one to one side of this base curve and the second coil to the opposite side, they will then line up when assembled.

You will need 3 files to do this red coil part, blue coil part, and an assembly containing both. Hint, once you create the first coil perform a save as to rename it and then flip the z direction in the sweep to create the second coil quickly.

In a cylindrical frame of reference the parametric curve for a log spiral is: r=A*exp(B*t)

where r is the radius and A & B are scalar quantities.

For example the equation in the  creo curve feature would take this form. Z=0 if the spiral lies within a single plane.

``````A=d11/2+2.6
B=0.348
z=0
theta=t*360
r=A*exp(B*t)``````

7 REPLIES 7
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## Re: Assembled Sweeps

If I were trying to assemble two coils like this I'd build both of the metallic coils based on a common set of datum planes, axes, or some other reference features. That way the assembly process would be simple.

## Re: Assembled Sweeps

@IBB98 wrote:
Hi, I have been creating sweeps of a small rectangular sketch attached to a spiral trajectory. I am trying to create a bimetallic coil, like the one in the photo below. I wish to model it in Ansys. However, to do this there needs to be two different materials (i.e. red and blue in the below photo are separate materials, and therefore separate objects).

My problem is that I have created the two spiral sweeps, and I'm having difficulty creating an assembly of the two joined together. They tend to overlap at the very center, and are constantly at 'partially constrained' status.

If anyone could help I would be very very grateful. The only constraints are that the entire assembly must fit into an envelope size of 50mm x 20mm x 15mm, so i left my outer spiral sweep with an outer diameter of 20mm. And that each material must be no less than 0.5mm thick. Thanks!

Hi,

upload your files (in zip archive), if you can. Maybe someone will investigate them and give you some advice.

Martin Hanák
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## Re: Assembled Sweeps

Thanks for the advice Martin, please see attached folder containing the two separate pieces and a failed attempt to assemble them.

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## Re: Assembled Sweeps

FYI for others, the posted models are educational version and can not be opened with a commercial license.

I would propose you do this using the following technique.

Use curve from equation to create a logarithmic spiral base curve. This curve would represent a curve that lies on the shared surface of the two "coils" as they are wound together as shown in your pictures. You can use this base curve to create both the red and blue coils as sweeps and then assemble each of them to a single assembly using the default constraint. Sweep one to one side of this base curve and the second coil to the opposite side, they will then line up when assembled.

You will need 3 files to do this red coil part, blue coil part, and an assembly containing both. Hint, once you create the first coil perform a save as to rename it and then flip the z direction in the sweep to create the second coil quickly.

In a cylindrical frame of reference the parametric curve for a log spiral is: r=A*exp(B*t)

where r is the radius and A & B are scalar quantities.

For example the equation in the  creo curve feature would take this form. Z=0 if the spiral lies within a single plane.

``````A=d11/2+2.6
B=0.348
z=0
theta=t*360
r=A*exp(B*t)``````

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## Re: Assembled Sweeps

I didn't even think about the fact I'm using an educational license slipped my mind, thanks for pointing that out.

Thanks so much for this incredibly detailed response, I will try it now and see does it work. Can i ask, is the dimension d11 used in the equation for A, equal to the outer diameter or is it another dimension?

Thanks so much again for your help!
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## Re: Assembled Sweeps

Ignore the stuff to the right of the = sign in the example for A, it is not directly relevant to your particular spiral, it was taken as an example of a spiral used to develop a volute for fluid flow.

A is the base radius that the spiral starts from. If you look at the form of the equation A represents the radius at theta=0 and it expands outward from that value.

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## Re: Assembled Sweeps

Thanks so much for your help, I have tried following your advice and it worked perfectly! I changed the values of A and B around, and after some trial and error, I now have a perfect working assembly that can be imported into Ansys for further testing.

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