Basket-Inspired Metamaterials Combine Stiffness With Resilience
Engineers at the University of Michigan have turned basket-weaving principles into lightweight, resilient metamaterials. These structures combine stiffness with the ability to recover after strong compression. They could support new designs for buildings, vehicles, robots, exoskeletons and other products that face repeated loads or impacts.
Basket weaving has existed for thousands of years. The craft allows flat ribbons to form complex three-dimensional shapes. However, the researchers found that weaving also offers clear mechanical benefits. It spreads stress across a wide area instead of allowing pressure to gather at weak points.
Recovering From Extreme Compression
The team wove thin Mylar polyester ribbons across each other at right angles. They then shaped the flat weaves into three-dimensional structures. Four corner designs connected three, four, five or six planes. The researchers also made identical forms from continuous, unwoven sheets of Mylar.
The woven boxes measured 17 centimetres tall. They returned to their original shape after the team compressed them by 14 centimetres. At that point, the boxes stood at less than 20 per cent of their original height. In contrast, the continuous-sheet structures suffered permanent damage under much lower pressure.
High-resolution 3D scans explained this difference. The woven structure spread stress across a larger area. The continuous sheets concentrated stress at individual points, where the material buckled and lost its shape.
Stiff Yet Flexible
Designers often associate woven structures with flexibility rather than strength. However, the woven samples reached about 70 per cent of the stiffness of the continuous-sheet versions.
More complex prototypes showed the design’s wider potential. An L-shaped structure, similar to a robotic arm, carried 80 times its own weight. It also remained flexible enough to bend upwards. A four-legged woven robot carried 25 times its weight while moving its legs. After the team crushed it with a larger load, the robot recovered its shape and strength.
The researchers also designed a woven exoskeleton concept. It could provide different levels of stiffness across the body while allowing movement and absorbing shocks.
Potential For Longer-Lasting Products
The modular corner system can create complex, lightweight structures that recover from repeated damage. This quality could extend product lifespans and reduce material use. However, the study examined mechanical performance rather than environmental impact.
The team now plans to add active electronic materials. These could help the structures sense their surroundings and change shape. Recycled, biobased or easy-to-separate ribbons could also make the system more useful for circular architecture, mobility and product design.
Source & image: University of Michigan