Lego-like Compliant-mechanism Building Blocks that Maintain their DOFs
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- Опубликовано: 4 окт 2024
- This video introduces the concept of configuration-indifferent compliant building blocks that can be assembled like Legos in any configuration or arrangement to produce compliant mechanisms of any complexity that achieve the same degrees of freedom (DOFs) as their constituent building blocks.
To learn more about how to design these special building blocks, see the published Precision Engineering journal article at this link:
www.sciencedir...
The reference for the paper is:
McCarthy, B., Nail, E., Nagarajan, A., McCullough, J., Hopkins, J.B., 2023, “Design of Configuration Indifferent Compliant Building Blocks,” Precision Engineering, 81: pp. 60-67
Part files to fabricate the examples shown in the video can be downloaded on Thingiverse using these two links:
www.thingivers...
www.thingivers...
Acknowledgements:
Special thanks to Jason Ma, Bennett McCarthy, Alexander McClelland, John McCullough, Naya Menezes, Michael Munguia, Mohammad sina Nabiee, Ashvin Nagarajan, Aditya Navghare, Johnny Nguyen, Phi Nguyen, Tommy Nguyen, Elizabeth Nail, Jimmy Penaloza, Supreethi Penmetcha, Wendyl Perez, and Shivam Kumar Panda.
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Disclaimer:
Responsibility for the content of this video is my own. The University of California, Los Angeles is not involved with this channel nor does it endorse its content.
Every new video from this channel is a treat! And sharing the designs with the public makes it even better. Thanks!
This channel is invaluable, thanks to the whole team
Fascinating! More genius insights into flexures just waiting to be used in practical desired mechanisms!
I wonder if this can be used against earthquakes.
This is really interesting. Plus, i like that the designs are so openly shared :) very nice.
We have an amazing application for that
How do we calculate fatigue for a device like this?
I am going to assume you mean material fatigue. You would need to know the material stress-strain curve, i.e., the maximum before ductile deformation, and design your device with those parameters in mind. Though typically on compliant devices: stops(limiters) are used to prevent over stressing the mechanism.
@@hadensnodgrass3472 thank you. Yes, that is what I was curious about. I'm not trained in the area of engineering that covers this. Can you recommend a place to start learning about stress-strain curves? How to understand them?
@@TracyNorrell At a very basic level, most stress-strain curves can be split into two parts: elastic and plastic deformation. The elastic part of the curve is often linear, with the slope being the Young's Modulus of the material. At some point the curve will change slope, which is the yield strength of the material. Now you're in the plastic deformation stage of the material, where it will be permanently deformed.
The Wikipedia article on stress strain curves isn't a bad place to start looking for more info.
So for flexures you want to keep the total stress in the material in the elastic region, below the yield strength of the material you're working with.
@@teguh.hofstee Thank you both for this great thread. I was also curious about this subject and found this illuminating video I think you'll like: ruclips.net/video/WSRqJdT2COE/видео.html
Prodigious !
I'm not sure that the structure at 3:50 really does have the same rotational stiffness as the original block as would usually be understood. Since each stack is off-centre of the rotation of the combined block, a rotation of the overall structure necessarily has additional translational motion on top of the same rotational motion, which should introduce additional stiffness. I suspect the stiffness would instead be the same as an equivalent off-centre rotation of the original block. I suppose that means the rotational motion is not truly fully scalable the same way translational is, at least with this simple setup.
Yes, the translations "scale" as you say but the rotations only do if you compare similar axes, which you can do because the rotational DOF can be any axis that is orthogonal to the two translations.
Interesting!
Do you know of any mechanical designs that might use something like this?
Because I don't normally design mechanical systems, but I am working on something that might use Compliant Mechanisms.
And to me, this is interesting... but I wonder what kind of applications it has. Many, I know, but I wonder what people use it in!
I suppose i could see it being used in a Game Controller, to allow a control stick to move (like the 3DS controller).
But there are more uses I'm sure...
I'm answering my own question, now.
:)
Anyway! Thank you for the video! :)
Cool
What material did you use to print those?
2:40
hold on
flip that upside down and rotate it 45 degrees.
thi figure is the same, but the 45 degree rotation still happened, so we can assume the starting thing can move in 4 directions, 2 orthogonal and 2 diagonal, with still the rotation.
Translating in X and Y is equivalent to translating along axes at 45 degrees, in the directions X+Y and X-Y. Both are saying you can translate in the 2D plane. That's still two degrees of freedom even though there are a lot more than two axes within the plane of motion. Is that what you were pointing out, or did I misunderstand?
@@jamiekawabata7101 oh, i thought the axes were seperate (not able to be done together)
good to know.
How about building those mechanism with molecules like phenol as the platform and another structure tu build the beams of your second hexagonal structure?
it is like proteins, same sequences repeat in DNA for multiple proteins, nature does the same.
I love this. Insightful.
Earthquakes begone.
not everything which is modular is necessarily Lego-like
I think that in this case "Lego-like" is a good description.
@@sethbettwieser It's really not, given the fact that Lego blocks do not change properties when configured in series or parallel arrangements whereas these flexures do, which is also clearly stated in the video as explained by the range of deformation and material stiffness. The only comparison is building blocks, but a brick house is more akin to Lego than these flexures are, modularity isn't a good argument for calling things Lego-like when there's really no other similarities; it's a false equivalence fallacy, no different from comparing apples to oranges.
@@xaytana counterpoint, they fit together by a nub on the top fitting into a slot in the bottom.
I do love a good semantics debate, and on that note... on the spectrum of Lego-like and generic modular constructs. I would place this device in the more lego-like portion of the spectrum on account of it having a nearly identical nub like protrusions in the vertical axis.
@@sethbettwieser Terrible counterpoint. Lego uses a partial-depth stud that relies on friction and some amount of flexion within the joint, not a full-depth rod that relies on no friction at all. The connection method here is quite literally a locating pin.
coming soon to an earthquake zone near you
"Lego" is a proper name and a trademark, and is never pluralized. The term you meant to use was "Lego bricks," not "Legos."
Lego doesn't own the place in my brain where the word Lego is stored. As long as meaning is conveyed, everything is fine. Language is constantly changing. Everyone knows that Legos would be more than one lego. Someone could easily infer that if you said "two Lego", you meant it as a plural noun. I will say Legos every time to save me from having to say the word "block" after it.
@@russelllukenbill edgelord
@@Barnaclebeard No need for ad hominems, just giving my opinion. Have a great day, I wish the best for you. Take care. 😸
@@BarnaclebeardNerd. Look up colloquialism. Language changes.
If the video creator is concerned about the legal repurcussions of how they represented the Lego brand, then this advice makes sense.
If they are just trying to speak their own dialect of English, then "Lego" as a collective noun could sound incorrect/like an affectation and would distract from the educational goals of the video.
I suspect Lego didn't focus on their preferred nomenclature in their marketing when the product first hit the US, and the accepted US plural was made without their input decades ago.