Feature Request: Compliant Mechanism Design

[brotherdustautodesk]

It would be very cool if F360 had native design and manufacturing workflows to produce assemblies or parts with integrated compliant mechanisms.

Why would this be useful?

1. Currently the best way to produce these types of mechanisms is iteratively, which is very time-intensive and requires a lot of trial and error. Recently, some research has been published describing how to produce CM's computationally. There's an entire lecture series on CM's and the research here: (38) Compliant Mechanisms Lecture Series - YouTube
2. In the context of, say, FFF manufacturing, these mechanisms are ideal: they can be made from the substrate material and printed in-place without additional parts. They are precise, durable, and simple.
3. Having a native, parametric design workspace that supports these will make them scalable, documentable, and encourage interest in their design.

What would a CM design workflow look like in Fusion360?

Since the method is computational, it might be similar to generative design, but have a few unique features:

• Constraints on displacement (usually no more than 30%)
• Additional material parameters (temperature sensitivity vs elasticity, etc)
• Warnings about poorly anchored mechanisms that might cause weaknesses

etc. I'm sure I'll think of more as time goes on, but at least wanted to get the conversation started.

[TrippyLighting]

Can you perhaps share an example?

I am not tempted to sift through a lengthy series of videos to figure our what you are referring to in my spare time 😉 

[TheCADWhisperer]

@TrippyLighting 

Search on Veritasium compliant mechanisms machines that bend are better. YouTube 

[brotherdustautodesk]

Here’s the referenced video: https://youtu.be/97t7Xj_iBv0

@CadWhisperer, do you think this would be a useful feature? If so, how would it be useful to you?

[TrippyLighting]

@TheCADWhisperer @brotherdustautodesk ahh, now it clicks. I had seen that (and other videos) before. Very interesting stuff!

Yes, I believe a feature set that would help develop these mechanisms would be right down Fusion 360's alley, so to speak.  I've posted a link to this thread on the Fusion 360 Slack channel soliciting some feedback.

[ElizabethGreene]

My 3D printable die filer is an example of a compliant mechanism in F360.   
Youtube: https://www.youtube.com/watch?v=IMSI0ZdddDE

.jpg and .f3d file on GitHub here: https://github.com/ElizabethGreene/3D-Printable-Die-Filer 

As the crank turns, the component named "Flexure" bends up and down to provide linear reciprocating motion.  I couldn't figure out how to model things that bend in F3D, so I didn't joint this component to the assembly.

Right now I'm trying to figure out how to increase the off-axis stiffness of it, and being able to model it would save me 3D printing a number of iterations to accomplish that.   That said, including how something like this deforms in an assembly "feels" like a super hard software problem, and I completely understand if it's not doable.

Thanks!

[brotherdustautodesk]

Thanks for sharing that!

Modeling a CM is a fairly well-understood problem space. I think the reason we perhaps don’t see (easily accessible) implementations is that the material properties must be characterized in a way that is more specific that just plugging in some numbers from a datasheet (though that would be a great place to start!).

In the context of FDM, many more variables are introduced: layer orientation, height, width, extrusion temperature, and so on.

As I said, it would be nice if Autodesk would consider this feature seriously; even a way to create a dead-simple flexure joint would be helpful.