Granular materials have always been a fascinating subject of study due to their unique properties. The ability of sand to behave like a liquid when placed in an hourglass, while remaining solid when walked upon at the beach, has intrigued scientists for years. However, the compressibility of these materials has always posed a challenge. Until now, researchers from the University of Amsterdam and Santiago in Chile have successfully designed new granular materials that can be easily compressed, opening up a world of possibilities for applications such as shock dampening.
On the coast of Japan, one can find tetrapods, giant four-legged concrete blocks that serve the purpose of preventing erosion. These tetrapods form a granular metamaterial, designed by humans to mimic the properties of sand. The unique shape of tetrapods, with extended legs, prevents them from flowing like regular boulders. This example illustrates how creating a granular system that is almost incompressible and less flowable than sand is relatively simple. However, the challenge lies in developing materials that are easy to compress and flow better than sand.
The groundbreaking research published in the Proceedings of the National Academy of Sciences by the researchers from Amsterdam and Santiago marks a significant shift in the field of metamaterials. By manipulating the geometry of materials, researchers were able to create grains that shrink radially under external pressure, leading to a material that is highly compressible and flows like a liquid. This innovative approach opens up avenues for creating packings that are both easy to compress and flow effortlessly.
One of the key applications of these new granular materials is in shock dampening. The researchers demonstrated that dropping a metal disk into a packing of the new grains resulted in a gradual slowdown and minimal bounce back. This mechanism allows for a more consistent and homogeneous transfer of energy, making it ideal for scenarios such as cushioning a fall in a speed skating race. The use of these new grains could potentially reduce the impact on the individual and improve overall safety.
The development of easily compressible granular materials that flow better than traditional sand represents a significant advancement in material science. The ability to fine-tune the properties of these materials opens up a realm of possibilities for various applications, particularly in shock dampening. The research conducted by the team from Amsterdam and Santiago highlights the importance of innovative approaches in material design and paves the way for future advancements in the field of granular materials.