Flexible mechanics make their mark on the world of machines

Transforming mechanical engineering

A sturdy, lightweight, powerful clamp, but without bolts or rivets... a dream.
A one-piece switch? Let's see!
A 25m2 panel that fits into 1m3? Powder, perhaps? Yet all these technical promises have been realized.

At the frontier between mathematics, engineering and origami, flexible mechanics opens up a new era in mechanical engineering.

Robust mechanics

Robustness is one of the most sought-after characteristics in mechanical engineering. It's important for a machine to last a long time, and to get the job done without failing. At the root of most mechanical failures are the joints between moving parts. These same joints are usually also the most complex parts. How can we reduce their number? The question is simple, and to answer it, we had to question a basic mechanical principle: rigidity.

Considered an essential quality, rigidity helps to avoid undesirable oscillations, material fatigue and parasitic vibrations, which can lead to premature wear, noise and breakage. The more rigid, the better...

With the evolution of our knowledge of materials and structures, engineering now makes it possible to design materials with varying degrees of flexibility and virtually infinite duration, as long as the application remains within the given parameters of temperature, pressure or tension. So why not use flexible materials instead of joints? That's what Larry Howell, a mechanical engineer at Brigham Young University, did.

One by one, he dismantled entrenched beliefs, demonstrating, for example, that rigidity and strength really aren't the same thing, that something can be flexible AND strong, and that strength depends on both the material, the structure and how the stresses are applied.

Getting closer to the ideal!

By playing with thicknesses, orientations, shapes and materials, designers achieve a level of simplicity approaching that of art, architecture or even biology. Of course, a great deal of expertise is required, including a thorough knowledge of materials, their properties and their shaping, but the result opens up prospects in almost every field, from agriculture to space and medicine.

Flexible mechanics (compliant mechanics) pursues several ideals, the 8 P's:

• Minimum number of parts: the number of parts is reduced by using flexible parts instead of springs, hinges, joints, bearings, etc.
  
  
• Production simplicity: The use of new materials radically simplifies production, assembly and handling.
  
  
• Price: By limiting parts and assembly, it goes without saying that price comes down. Especially when you can extrude or 3D print at marginal cost.
  
  
• Accuracy: Depending on the production process, in the absence of joints, the level of accuracy exceeds that possible with conventional mechanics.
  
  
• Performance: No need for lubrication, silent, lighter, increased performance and durability.
  
  
• Proportionality: You can change scale and materials as required, while retaining the same principles: flexibility is also relative to size, from tiny to huge.
  
  
• Portability: lighter, thanks to fewer and simpler parts.
  
  
• Predictability: products maintain their performance over time, and are generally more reliable.
  

To achieve these objectives, simplicity and the absence of joints are two of the principles pursued.

Origami to the rescue

Origami makes it possible to create 3D shapes from 2D plans, which are then unfolded in various directions to form a continuous, seamless structure. The practical relationship with flexible mechanics is a natural one. With 3D processing software, of which you'll find a few examples in the references, origami can enter the world of engineering. Not only have designers been guided by tradition, they have taken origami to a new level, creating structures that are both useful and aesthetically pleasing.

We're only at the beginning of this discipline, and already its applications have entered our daily lives without us even noticing. You may have already noticed some flexible mechanisms in recent electronic devices. But that's just the beginning! This knowledge is spreading fast and is starting to enter engineering faculties...

References

BYU Compliant Mechanisms Research Group - https://www.compliantmechanisms.byu.edu/

Why Machines That Bend Are Better - https://www.youtube.com/watch?v=97t7Xj_iBv0

Handbook of Compliant Mechanisms by Larry L Howell - on Google books
https://books.google.ca/books?hl=en&lr=&id=obD5SnfVUxkC&oi=fnd&pg=PR11&ots=ixfa-FdE-g&sig=ls1L3iiTdzb--A0LptdlPfEwmIw#v=onepage

Handbook of Compliant Mechanisms by Larry L Howell - on Amazon
https://amzn.to/2uS7ZIq

Origami Applications

• Origami Draw App (iOS)
• Free Form Origami and Origamizer (Windows)
• ORI-REVO: Design Tool for 3D Origami of Revolution - Mac OS and Windows
• Origami simulator
• Fold - Powerful origami java applications