Wrap a solid part?

marcel_robitaille742

Hi,

I am trying to wrap a solid part onto a cylindrical surface. I would like to create a carbon nanotube like this: https://www.researchgate.net/figure/9-Types-of-carbon-nanotubes-a-armchair-b-zigzag-c-chiral-Reproduced-from-55_fig9_305766738

I want to do it in a very general way so I can change the chirality (armchair, zig-zag, anything in between, see previous image). I created an unwrapped hexagon grid where I can choose the angle to wrap with. Then, I dynamically create a cylinder with the correct diameter and angle, and I take the intersection of my grid with a rectangle rotated at that angle. The problem I am facing is that I can't wrap this part around my cylinder.

https://cad.onshape.com/documents/50ac3adf2caa6a34ef62284b/w/c54a3fa352972f0d6fccdf70/e/e271e671b6571f5fea5b2e0e

I also considered wrapping the sketch, but I don't know of any way to dynamically take the intersection of the sketch of the hexagon grid and the rectangle, or to dynamically add thickness to the edges of the wrapped surfaces on the cylinder. I know how to manually do it with the cut tool and by meticulously clicking each edge of the wrapped surfaces, but that breaks as soon as I change the angle.

Is there any good way to achieve this carbon nanotube effect?

NeilCooke

You can take a look at how I made this stent https://cad.onshape.com/documents/b83dc10d6b29c75030524556

marcel_robitaille742

Thanks for the answer, but that's not what I'm looking for. In this example, you are wrapping a sketch onto a cylinder and then extruding that sketch. My issue is different. I already have a 3D structure that I want to wrap onto a cylinder. I cannot do the former for reasons I discuss in my original post.

shawn_crocker

Just trying to be sure I'm getting what your intent is.  Simply put, you want to make a primitive shape (cylinder).  You want to also have another more complex object that will be patterned onto the primitive (or wrapped) in a way where the pattern shape automatically reforms itself to maintain perfect spacing.  You then want to be left with a solid in the shape of the primitive (cylinder) but constructed of the patterned object.  you want to be able to control the thickness of the finished solid.
Is this correct?

steve_shubin

@marcel_robitaille742

https://cad.onshape.com/documents/c98fbdae3809fbf91e3b336e/w/09b4fc4001e5fb93fcaffd0a/e/f7dcd57e17acccad6009cb87

If you’re looking for one part studio where you can modify one variable and change it from zigzag to armchair or chiral, well that’s not what I’m doing here.

I’ll give you one part studio for an adjustable zigzag and another part studio for an adjustable armchair. And MAYBE another part studio for an adjustable chiral

To have the ability to do all of those from one part studio, well I’d have to think about that for a while. Can’t guarantee anything

OK, but for the meantime, here is zigzag

Now I might be giving you a little bit more with regards to zigzag than you’re asking for, in that you can adjust the thickness and the width all using variables.

I can modify this part studio and give you armchair, maybe later this evening if I get some time to do that

In order to adjust either of these parts studios, do it only from the variables. And within those variables, the only thing you should tweak is the number or the amount

Take note that once you adjust a variable, it takes a little time for this thing to regenerate

steve_shubin

@marcel_robitaille742

Armchair has been added in to the above document

To make the ends of the nanotubes look good, it’s going to require a couple MOVE FACE features. And every time you modify the nanotube, you’re going to have to tweak these. So save these two adjustments for the very last

steve_shubin

@marcel_robitaille742

I looked closer at the link that showed the three different examples and I noticed a couple things that I didn’t catch the first time

These nanotubes are not circular. They’re  faceted when viewed from overhead or from plan view or top view. So the way I see it now, wrapping doesn’t seem to make sense because wrapping is applying something to a circular surface and these things are not circular

The other thing my eyes didn’t catch the first time — is that they are round tubes. So what I’ve done is not going to make any sense for what you’re looking for

I did notice that you had a part studio where it looks like you did a pretty good job. So now you can plug in some variables so you can adjust the diameter or hexagon size and what not. Maybe the size of the tube. That type of thing.

But it looks like you’re getting it figured out

eric_pesty

Haven't gone deep into this but isn't each "ring" always the same size? In which case it should just be different patterns of solids with no actual "deformation happening? Or do the rings get distorted in the chiral configuration?

Maybe you would just need to start with a "cloud" of 3D points and "connect the dots", could the "Frame" (or Beams feature) help here?

marcel_robitaille742

Thanks for all the responses. You are all so kind for helping me Sorry for the delay. I got very busy.

@shawn_crocker

Just trying to be sure I'm getting what your intent is. Simply put, you want to make a primitive shape (cylinder). You want to also have another more complex object that will be patterned onto the primitive (or wrapped) in a way where the pattern shape automatically reforms itself to maintain perfect spacing. You then want to be left with a solid in the shape of the primitive (cylinder) but constructed of the patterned object. you want to be able to control the thickness of the finished solid. Is this correct?

Yes, that was my idea, but maybe it's not the best way to do this.

@steve_shubin

Thank you so much for taking the time to make a document with this!

These nanotubes are not circular. They’re faceted when viewed from overhead or from plan view or top view. So the way I see it now, wrapping doesn’t seem to make sense because wrapping is applying something to a circular surface and these things are not circular

That is correct. Making them cylindrical is a compromise I was willing to make. I thought it would be easier. The carbon atoms should all be on the surface of a cylinder, but you're right, the bonds between them are not. I am just trying to make a figure to explain someone what a carbon nanotube is who has never seen one.

I did notice that you had a part studio where it looks like you did a pretty good job. So now you can plug in some variables so you can adjust the diameter or hexagon size and what not. Maybe the size of the tube. That type of thing.

But it looks like you’re getting it figured out

If you mean the other part studios, those are all tests. They are not general, and I think I only managed to make zigzag, I couldn't even figure out armchair. The zigzag one is similar to what I want, but I want to produce all other chiralities just by changing some parameters.

@eric_pesty

Haven't gone deep into this but isn't each "ring" always the same size? In which case it should just be different patterns of solids with no actual "deformation happening? Or do the rings get distorted in the chiral configuration?

No the rings are not always the same size. Even for the same angle (like armchair), the diameter can change by adding an extra carbon atom to the ring.

Maybe you would just need to start with a "cloud" of 3D points and "connect the dots", could the "Frame" (or Beams feature) help here?

I haven't used those before. I thought of something like that, but I didn't know how to do it in a general way. I was thinking to use Featurescript or openscad but if you recommended it, maybe there's a way in OnShape? I also didn't know a good way to make a cloud of points in OnShape. I know some softwares have 3D sketches, but I don't think OnShape does. I will look into it. Thank you.

eric_pesty

I believe there is a custom feature for a bunch op points (called 3D point cloud or something like it) but I haven't used it so I don't know if you can "configure it" on the go...
I still think the key is to find the smallest "chunk" you need to draw before you can create the rest with a pattern (and a few boolean / cuts at the end to clean things up). 

Just to be clear when I was talking about "rings", I meant hexagon of 6 C atoms, not "slice" of the tube. I would expect these to be all the same shape at least within each "configuration" of the nanotube so I would start with modelling one of these and then look at ways to pattern them (rather than try to draw "the whole thing").