Project Update #9: Compliant mechanisms printed with PolyFlex!

We have been asked many times on the potential applications of PolyFlex. Well, we have already provided examples such as belts (like the one in the video), shoes, phone cases, toys, etc. But the question is always: what else?  

I was recently introduced to the website of Compliant Mechanisms Research at Brigham Young University (CMR@BYU). I was instantly amazed by the fascinating concept of compliant mechanisms. To explain this, we should first see what a mechanism is. By definition, a mechanism is “a mechanical device used to transfer or transform motion, force, or energy”. Traditional mechanisms are mostly rigid-body mechanisms that consist of rigid links connected at movable joints. In contrast, compliant mechanisms “gain at least some of their mobility from the deflection of flexible members rather than from movable joints only”. Let’s see an example that is provided on the website:


In the example, the crimping mechanism of the vice grips is realized in two ways: rigid-body mechanism (left) and fully compliant mechanism (right). They are both capable of transferring the input force to the output port.  

So why are compliant mechanisms important? It is because they have several key advantage over traditional rigid-body mechanisms: 

1. Compliant mechanisms often require a much smaller number of parts to perform a certain task. Consider the example again, the vice grips based on the rigid-body mechanism are composed of more than 10 parts (if I counted right) assembly together. And how many parts do you need for the compliant mechanism? Only one! The dramatic reduction in parts can greatly simply manufacturing time/complexity, assembly time, product weight, cost, and reduce wear and the need for lubrication. 

2. In compliant mechanisms some energy is stored in the form of strain energy in the flexible members (similar to the potential energy in a compressed spring). This can be good or bad actually, but it can certainly be utilized to accomplish tasks more easily in some applications. 

3. Compliant mechanisms can be more easily miniaturized, making them ideal for applications such as microstructures, actuators, sensors, and even microelectromechanical systems (MEMS). 

Another advantage, in our opinion, is that you can easily prototype or even make real devices based on compliant mechanisms using 3D printing! And PolyFlex is the ideal material (“flexible member”) for this, given its good flexiblity. We have printed the vice grips example ourselves. 





CMR@BYU has generously provided many examples of compliant mechanisms that are free to download from their website: It is a great toolbox for designers and engineers who use 3D printing. Most of the provided examples can be easily printed with PolyFlex.

You can also view a list of commercialized applications of compliant mechanisms here:  Some of them are really interesting! 

Hope you enjoy this update!