Tunable Stiffness Compliant Mechanism with Bistable Switch - Binary Stiffness (Part 3)

This video depicts a translational binary stiffness compliant mechanism that achieves two different states of stiffness by being triggered using a simple bistable switch. One state is very compliant while the other state is very stiff. The mechanism was designed by Reinier Kuppens while working in my lab at UCLA as a visiting scholar from Delft University.

Further details about the mechanism are published in the Journal of Mechanisms and Robotics, and can be found at this link:

A raw video of this mechanism was previously uploaded to Reinier’s YouTube channel:

but this video is intended to explain the mechanical principles behind how the mechanism works. This video is the third part of a five-part mini-series about binary-stiffness compliant mechanisms. Be sure to watch the other parts to learn more about how they work and for what applications they could be used.

The part files for this mechanism can be downloaded from Thingiverse at this link:

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:
This video would not have been possible without the brilliance of Reinier Kuppens, Just Herder, and Miguel Bessa, so a huge thanks to them.

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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.

[PianofortheSoul]

My dear son, I love hearing your delightful voice narrating genius videos like this!

[samheasmanwhite]

I recently repaired a Willomore seismometer that uses this principle to almost completely eliminate the stiffness of the springs that suspend the weight.
There is almost no force returning the weight to centre when it is properly tuned so it's resonant frequency can be less than 0.1Hz, to pick up those really slow earthquakes.

[gabethedinosaur]

I'm entering my first year of college as a mechanical engineering major; it's videos like these that inspire me to design my own mechanisms and pursue the oddities of classical mechanics! Thank you!

[soorajkadnor]

These kind of mechanisms will bring a revolution in our technologies.
Keep it up.

[paulromsky]

That plot at 1:14 is similar to a Zener Diode. Current is the Y axis and voltage is the X axis. When a Zener Diode is reversed biased, at certain point in voltage it will remain constant over a various change in current (the left knee in the graph - the Zener point). That is how Zener Diodes regulate voltage.

[darth_dan]

I've seen compliant deformation mechanisms before, but this one finally explains the concept, and now I really want to find a way to implement it in a practical application...

[jameshopkins]

Jonathan, I love your videos! It appears to be taking off like wildfire. Congratulations!

[swedneck]

oh wow this actually went from utterly inscrutable to obvious after that explanation, that's impressive!

[darkling-studios]

why am i here, when did i get here, i have never once over the course of my entire life sought out mechanical design or the application of stiff and non stiff mechanisms, but i watched, i understood, and i was intrigued the whole time.

[Andersmithy]

no idea why this showed up in my feed, but very cool nonetheless. I couldn't figure out why you'd want something like this until the end where you showed the "self-switching" ability of the device. Then it 'clicked' for me!

[andramoie]

The pacing of the explanation is perfect. Well done!

[lohikarhu]

Hey Jonathan! I had "followed" your work for a long while, but just found this channel today!
Nice to see you making this interesting work both accessible and understandable, on this platform.
I have often seen designs in industry, using "classical" bearings and sliding mechanisms, that could really have benefited from proper application of flexure-based designs... Hope that you're keeping well, and that life is treating you well!

[mohsena]

Congratulations for your success in this project. As always it's amazing to watch your innovative projects

[Princess_Sophiekins]

I love learning, and with your channel, I am never disappointed. Thank you! Happy New Year!

[goodiesohhi]

I'm glad youtube decided that THIS was was something I needed to watch haha.

[namename]

Anytime I have a system that needs stiffness cancellation, I just think about baseball or my grandma. Works every time!

[sinuture]

This is really interesting idea!
It might realise “physical computer” as I have seen a computer by using water flow. Computers without electron excite me.

[RatkingNyxu]

My mind immediately went to a failsafe mechanism or perhaps even a prop-knife. Producing a compliant mechanism that allows the blade to appear rigid until enough force is applied- at which point the bistable mechanism causes the blade to retract freely could be incredibly useful.

[aaronclair]

The application I thought of first: a vehicle suspension with a stiff on-road mode and a soft off-road mode. There are other ways to accomplish this (pneumatics, hydraulics, electromechanics), but this mechanism could probably build a two-mode suspension with just springs and shock absorbers.

[Adamsmasher]

This is very cool, thanks for sharing and for the detailed and accessible explanation!