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New foam-like shock-absorbing material protects like a metal

[Image credit: Will Kirk/Johns Hopkins Univeristy]

 

 

By Jason Lucas, Johns Hopkins University

A team of Johns Hopkins University researchers has created a shock-absorbing material that protects like a metal but is lighter, stronger, and reusable. The new foam-like material could be a game-changer for helmets, body armor, and automobile and aerospace parts.

"We are excited about our findings on the extreme energy absorption capability of the new material," said senior author Sung Hoon Kang, an assistant professor of mechanical engineering. "The material offers more protection from a wide range of impacts, but being lighter could reduce fuel consumption and the environmental impact of vehicles while being more comfortable for protective gear wearers."

Kang, who is also a fellow at the Hopkins Extreme Materials Institute, wanted to create a material even more energy-absorbing than current car bumpers and helmet padding. He noticed the typical materials used for these critical protective devices don't perform well at higher speeds and often aren't reusable.

The research team increased the material's ability to withstand impact by using high energy-absorbing liquid crystal elastomers (LCEs), which have been used mainly in actuators and robotics.

During experiments to test the material's ability to withstand impact, it held up against strikes from objects weighing about 4 to 15 lb coming at speeds up to about 22 mph. The tests were limited to 22 mph due to limits of the testing machines, but the team is confident the padding could safely absorb even greater impacts.

Kang and his team are exploring a collaboration with a helmet company to design, fabricate, and test next-generation helmets for athletes and the military.

The results appeared in the journal Advanced Materials. In this article, the material was described as having an energy-absorption density that "is two orders of magnitude higher than the same structure fabricated from poly(dimethylsiloxane) elastomer and is comparable to the dissipation from irreversible plastic deformation exhibited by denser metals." The article summary said, "The sequence of cell collapse can be controlled by grading the beam thickness to further promote viscous dissipation and enhance the energy-absorption density. It is envisioned that the study can contribute to the development of lightweight extreme energy-absorbing metamaterials."

Contact info for Sung Hoon Kang, assistant professor of mechanical engineering, is available here.

Published March 2022

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