New shock-absorbing material as strong as metal but as light as foam

Researchers at Johns Hopkins University have developed a new shock-absorbing material that’s super lightweight, while still providing the protection of metal.

The material could lead to lighter, stronger and, above all, reusable helmets, armor and vehicle parts.

The key to the new material is something called liquid crystal elastomers (LCE). They are networks of elastic polymers in the liquid crystalline phase which give them a useful combination of elasticity and stability. LCEs are normally used to make actuators and artificial muscles for robotics, but for the new study, the researchers investigated the material’s ability to absorb energy.

The team created materials consisting of angled LCE beams sandwiched between rigid support structures. This basic unit has been repeated across the material in multiple layers, so they deflect at different speeds on impact, effectively dissipating energy.

In a series of experiments, the team tested the material’s ability to withstand impacts from different masses at different speeds. The materials were struck by objects weighing between 1.8 and 6.8 kg at speeds up to 35.4 km/h and, indeed, they resisted.

As expected, the material performed better with more cell layers. A four-layered structure, for example, had nearly twice the energy absorption density of a single-layered structure.

Although the materials have so far only been tested with impacts of up to 22 mph, the team says they should also be able to absorb impacts at higher speeds.

Researchers say the material could be used to improve the safety of helmets, body armor, car bumpers and other vehicle and aircraft parts by effectively dissipating impact energy while remaining light.

We are delighted with our findings on the extreme energy absorption capacity of the new material. The material offers more protection against a wide range of impacts, but being lighter could reduce fuel consumption and the environmental impact of vehicles, while being more comfortable for wearers of protective equipment.

Sung Hoon Kang, associate professor of mechanical engineering.

The first use case will be helmets, as the team is currently working with a company to design and test this type of protective gear for athletes and the military.

More information: (English text).


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