Auxetics are materials that store energy internally rather than bulging out. In this way they can store more energy when squeezed or struck and disperse it more regularly. Historically, however, these materials have had sharp corners that could break easily with enough pressure. Now researchers at Queen Mary University of London and University of Cambridge have discovered a way to use auxetics in a more efficient and less fragile way. In this way you can create systems that store energy and release it mechanically multiple thousands of times.
“The exciting future of new materials designs is that they can start replacing devices and robots. All the smart functionality is embedded in the material, for example the repeated ability to latch onto objects the way eagles latch onto prey, and keep a vice-like grip without spending any more force or effort,” said Queen Marry University’s Dr. Stoyan Smoukov. For example, a robot using this system can close its hand over and object and keep it closed until its time to let go. There is no need to continue sending power to the claw or hand until it is time to open up and drop the object.
“A major problem for materials exposed to harsh conditions, such as high temperature, is their expansion. A material could now be designed so its expansion properties continuously vary to match a gradient of temperature farther and closer to a heat source. This way, it will be able to adjust itself naturally to repeated and severe changes,” said Eesha Khare, an undergrad who worked on the project.
The project used 3D printing to make small clips that grab a toothed actuator. To release the energy, you pull on the opposite sides of the object to release the teeth. While the entire thing looks quite simple the fact that this object stores energy without bulging is important. The same technology can be used to “grab” bullets as they strike armor, resulting in better durability.