Researchers from the University of Glasgow working with the Polytechnic University of Marche, the University of L’Aquila, and the National Institute for Nuclear Physics in Italy, have developed a 3D printed material that can twist under impact, offering the potential for adaptive crash protection in vehicles.
“The protective materials used in most vehicles today are static, designed for specific impact scenarios and unable to adapt to varying conditions. This study introduces adaptive twisting metamaterials as a new class of metamaterials that don’t require any complex electronics or hydraulics to adapt. Instead, they can adapt simply through mechanical control of rotation. When we apply compression, the gyroid lattice translates it into twist, and by changing the boundary conditions, we can tune the energy absorption characteristics. These materials can adapt and change their own characteristics depending on the impact type and severity to mitigate effects,” said Professor Shanmugam Kumar of the University of Glasgow’s James Watt School of Engineering, who led the study.
Adaptive Twisting Design
Described in Advanced Materials, the paper titled ‘Adaptive Twisting Metamaterials’ employs a distinctive gyroid lattice structure. Unlike traditional foams or crumple zones that offer fixed resistance, this material can mechanically adjust its response to different types of impacts. It can be tuned to provide stiffer resistance for heavier collisions or softer cushioning for lighter ones.
Made from steel using AM, the process allows precise control over the material’s intricate, highly porous lattice. When compressed, the gyroid structure twists in a corkscrew-like motion, dissipating impact energy.
Laboratory tests examined three configurations of the material under rapid impacts and gradually increasing strains. When prevented from twisting, it achieved maximum stiffness and absorbed 15.36 joules of energy per gram. Allowing it to twist freely reduced stiffness and energy absorption by about 10%, while over-twisting decreased energy absorption by 33%. These results suggest the material can offer a spectrum of protection, from rigid shielding to softer cushioning.
The experiments were supported by theoretical and computational models that predict the behavior of twisting gyroid lattices under varying strain rates. Geometric imperfections from the 3D printing process were quantified using micro-CT scans to ensure accurate alignment between simulations and experiments.
“We believe the material could find applications in both automotive and aerospace safety in the future, providing a single new class of material capable of adapting to different needs as required. It could also support the development of novel forms of energy harvesting, by converting impacts into rotational kinetic energy,” said Kumar.
Research in 3D printed lattices
Beyond vehicle safety, similar 3D printed lattices are being developed to enhance stiffness, energy absorption, and vibration management in other fields.
At RMIT University, researchers created a bio-inspired double-lattice structure inspired by the deep-sea sponge Venus’ flower basket. This lattice achieves 13× stiffness and 10% higher energy absorption than conventional auxetic materials, maintaining auxetic behavior over a 60% larger strain range. According to the paper published in Composite Structures, applications could include construction, protective gear, and medical implants. As Dr. Jiaming Ma, lead author of the study explained, the research addresses this limitation by developing a double-lattice structure that optimizes load distribution and deformation resistance.
In another development, a team led by Professor Chiara Daraio from ETH Zurich developed a rigid plastic lattice with embedded steel cubes capable of absorbing vibrations while supporting weight. The steel cubes functioned as resonators, prevented vibrations from propagating through the structure, and made it suitable for spacecraft, turbine rotors, and rockets. “Instead of the vibrations travelling through the whole structure, they are trapped by the steel cubes and the inner plastic grid rods, so the other end of the structure does not move,” explained Kathryn Matlack, a postdoctoral researcher in the group.
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Image featured shows experimental and computational comparison of adaptive twisting metamaterials. Image via University of Glasgow.
