Binary-stiffness Compliant Mechanism that Achieves Two Translations

This video introduces a multi-degree-of-freedom binary-stiffness compliant mechanism that achieves two different states of stiffness by being triggered using a bistable switch. One state is very compliant and allows for deformation along two orthogonal translational directions while the other state is very stiff and resists deformation in all directions.
Details about this video are published in the Journal of Composite Materials, and can be found at this link:
journals.sagepub.com/doi/full...
STL part files can be downloaded at the following Thingiverse link if you’d like to 3D print and assemble the compliant mechanism and play with it yourself:
www.thingiverse.com/thefactso...
Also, to understand more about compliant mechanisms in general, be sure to watch the other videos in my Compliant Mechanism Design series on this channel.
Acknowledgements:
I’m grateful to my students Sam Shimohara and Ryan H. Lee who helped to optimize, fabricate, and test the mechanism. I’m also grateful to my AFOSR program manager, Byung “Les” Lee who provided the funding to support the creation of this mechanism.
Donate to help support my channel:
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PayPal.me/FACTsMechDesign
Thank you for your support! It is much appreciated and helps enable me to make more content.
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.

[@simonfox_8559]

Great explanation, i like how i can understand how the mechanism works instead of it just being like ok heres a cool mechanism

[@erwinmulder2715]

With one or two design iterations it should be possible to really achieve near-zero stiffness. :) Very cool mechanism!

[@ARVash]

A joystick with variable sensitivity, simply and mechanically, sounds like a pretty useful thing to have.

[@BenRyherd]

Very neat mechanism. This exact layout seems better suited for "more limited" and "less limited" travel of the translational stage. If you're going for "no movement" or "free movement" it seems like you'd be better off to remove all of the yellow components and just make your red bistable switch have a pin on the end that locks into the translational stage.

[@alifalafel4831]

Excellent explanation, very interesting mechanism!

[@viniciusfriasaleite8016]

That is really amazing!

[@wreckervilla]

I'd like to see a binary variant that allows two or more states where the output could be set and a switch to make translating to either state less stiff

[@EmilFihlman]

Great and very interesting stuff!

[@AjSmit1]

cool mechanism. the stiffness cancellation is neat.

[@cienciaeneldesierto1095]

you are simply the best !

[@mmv365]

Well nice explanation final blue curve is my ride and handling bushing stiffness for Control arms in and other chassis structures

[@sapiosuicide1552]

Very cool

[@brettfafata3017]

Do you have any reccomended reading for compliant mechanisms? I completed my Bachelors in Mechanical Engineering and compliant mechanisms were not mentioned even once in all of my courses.

[@TheFACTsofMechanicalDesign]

Yes, Larry Howell's Book on Compliant Mechanisms is excellent.

[@CorvidianSystems]

only $120-180USD 😖

[@Mawyman2316]

@@CorvidianSystems It's free if you know where to look.

[@uirwi9142]

kinda like a big accelerometer that you could lock into place during take off, then loosen up once all the vibrations have ended, outside of the atmosphere.

[@curtmcd]

So much work and talent went into the design, implementation, paper and video. I just feel the product is bulky, unresilient and without practical application. Surely there are better use cases to showcase compliant mechanisms?

[@bahadirm]

I love compliant mechanisms, but I'd like to see real usecases, preferably something that maybe everyone uses but no one knows about it.

[@rubenexplains2640]

A simple one is the lid of a shampoo bottle. A more exotic one is the mirror alignment mechanism in the James Webb Space Telescope.

[@scambroselauntrellus3681]

I have no background in engineering and this is absolutely crazy to me.

[@rickpiller9285]

Can this be used to isolate a table with legs on four of them?

[@tomsko863]

Can someone please explain to me what F(kT1) means at 3:52? When the object is displaced +5cm (to the right), the force coming from the spring would be pulling back (to the left). Wouldn't the graph show a line from the top left to the bottom right? Is F(kT1) how much the "user" is pulling back on the object?

[@tomsko863]

@@BharatKambalur It does make sense (in all the graphs) if you assume F(kT1) is the force that the "user" would have to use to get the object to the position "x". So to keep the object in position "X" you would need to exert a force "N" on the object to keep it in that position. Basically, it's ambiguous what naming convention the author is using but the graphs are correct in amplitude.

[@michaelthompson8251]

amazing. how could this be applied to a worm gear

[@pauljs75]

In layman's terms: It looks like a way to make a joystick self-centering or non-self-centering, possibly by mechanically moving some kind of bezel around it. (At least it seems one of the most obvious applications.)

[@draganignjatovic4812]

Surely you could have used Yellow and Light-yellow instead of complicating things with Orang and Yellow? Thank you.

[@planckstudios]

'repeatable for practical applications'. I give those printed wire tuning springs < 1000 reps before they're deformed and unreliable. That's not practical compared to other solutions. It's novel and innovative for sure. flexures will be little more than a curiosity to most makers until simulations and metal printing are more common

[@andrewphillip8432]

How do you think the tuning springs would fail? There are so many of them in parallel that they might not be stressed very highly. Also they should load share pretty evenly since the plastic will creep a little bit initially, so if manufacturing tolerances cause one string to be a bit too short it will just stretch.

[@ARVash]

Strong disagree with Jonathan, I can think of long thin deformable things in machines that work for literal decades. Spring steel for example, leaf springs like this in firearms such as the sear spring in the 1911 last a very, very long time.

[@planckstudios]

@@ARVash those are metal. I said when metal printing is more common, flexures will be more useful. Until then, most plastics will deform dramatically over time given heat and stress

[@planckstudios]

@@andrewphillip8432 they won't register the same tension over time. Depending on the plastic, it can absorb water, degrade from UV, become more brittle over time - developing imperfections and differences between the springs

[@johanness6545]

As you can read in the publicly available paper "Mechanism reliability of bistable compliant mechanisms considering degradation and uncertainties: Modeling and evaluation method", there are methods to evaluate the durability. Polymer compliant mechanisms can be designed to last for hundreds of thousands of cycles. Indeed metal parts can be more durable, however they are more expensive and difficult to manufacture. There also good examples of subtractive manufactured metal parts in compliant mechanisms (often wire EDM), e.g. the mirror positioning actuators on JWST

[@denysvisser]

I think repeatability was hampered by your 3d fabrication method. It looks to be FDM? While good for hobby I don’t think it’s great for what are doing.

[@DuhDawg]

That's cool so I'm assuming this is like a scale model for earthquake protection for buildings or something

[@bekipitz472]

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