How to reproduce phisical deformation?


#1

Hi,
I am wondering how to reproduce some phisical deformed shapes, like a chain that is twisted with a machine, and then pressed to form a typical jewellery item.
To be clear I add a link to an image of such a deformed chain.
http://www.alchemian.com/catena-alluminio-maglia-ritorta-13x9mm-diamantata-argento-1m.html

I have tried 3 ways:
1 - make an elliptic path, twist it, sweep 1 rail a section on it.
2 - make an elliptic path, sweep 1 rail a section on it, twist the nurbs surf.
3 - make an elliptic path, sweep 1 rail a section on it, create a cage (3x3x3), twist the edit points of the cage.

All these 3 methods give very different results…wich is the closer one to the actual deformation of a chain?

Last but not easier, how to “press” the chain and obtain the final shape…?
Thank you!

Leonardo


(Kyle Houchens) #2

here’s my crack at it!
https://dl.dropboxusercontent.com/u/3443930/chain.zip


#3

Thanks,

but this is related to a simple torus…what if you have to model a chain that has a non round section?
Why did you cut the torus and blended it?
Thank you!
Best


#4

Rhino has no way of doing this automatically…that I’m aware of…you’ll need to just model the final shape from scratch as you imagine it.


#5

Leonardo,
As has been discussed there is no easy automatic way of doing this in Rhino as of now although there might be some kind of plugin out there that is doing realistic physical deformation modeling.
As you work on a manual solution, a good guide point is to remember that whatever is deformed will retain the same total volume as the input shape. So a chain link in this example, after being squeezed down will have the same amount of gold in it. Thus you can start to map our how the final link will look with a box that is lower in height and wider, that has identical volume. From there you can start modeling the shape of the link accordingly. (though to be honest, after zooming into those chain links in your original post, I almost think the flats are being ground off, not pressed, as I see no indication of elongation/deformation at the transition areas from flat to cylindrical. Or the links are being cast that way.)


#6

Hi,
thank you for your reply.
Actually those kind opf chains are pressed, the shown one is only an example but not exactly what I was trying to model.
Another related question is about the 3 different ways (explained in my first post), that give very different results.
I would like that someone at McNeel would tell us wich twisted model is the more realistic…
What do you think?
Best,


#7

Kyle, nice job on this btw. Looks good to me.


#8

Leo, I think expecting someone from McNeel to be an expert on metallurgical deformations of gold chain links is asking a bit much. You might be better off taking the 3 versions of your model (screenshots, dwgs) and either analyzing/reverse engineering some links yourself or taking to another expert in that specific field.
As I keep getting closer to the heart of the topic for you, I’m thinking that you are looking for something more like simulation software. Here’s something from a quick Google: http://www.simufact.de/en/news/nr_21_10_2013.html

Accurately simulating the deformation of metal is an incredibly complex process. Fast computers and better software has made it realistically achievable, but Rhino is not your app for this. However if you are just looking for a very close approximation then Rhino can indeed be the app for modeling it yourself.


(Kyle Houchens) #9

for non round section, I’d use a circle deformed to the correct shape then sweep1 with the profile you wanted. The blends in my file came from the kinks when I deformed the torus- I just split them out with split by isocurve- then blend to make a nice smooth transition-