June 23rd, 2015

Technologist

This new compression design could be the thing that keeps you out of the auto body shop next time you accidentally back into an unseen post. The prototype above is a 3-D printed, 3.5-inch nylon structure that can repeatedly absorb the energy of a 100 mph fastball in 0.03 seconds.

Mechanical engineers at the University of Texas at Austin weren’t content with the shock absorbers commonly used in automobiles, football helmets, aerospace applications and military gear. Even the newer honeycomb-patterned materials, which can compress only once during the force of a collision, weren’t good enough.

So they rethought what happens when an object gets crushed and came up with a structure they call a negative-stiffness honeycomb, which can absorb energy from an impact and then return to its original shape. Read more and see an infographic below.

In a paper published in the journal Integrating Materials and Manufacturing Innovation, they say negative stiffness occurs when a mechanical system requires a decrease in applied force to generate an increase in displacement.

This phenomenon is illustrated in their prototype structure above. Notice the curved beams that comprise each honeycomb unit cell. These absorb energy through elastic buckling rather than plastic deformation, meaning that they return to their original position when the force is removed.

They believe this type of shock absorber could be useful in vehicle bumpers, orthotics and personal protective devices. The design can be customized to absorb different amounts of energy and have different properties.

“Whether you’re serving our country in uniform, playing in a big game, or just driving or biking to work, the potential for multiple collisions or impacts over time — however big or small — is a reality,” said mechanical engineering professor Carolyn Conner Seepersad, who led the research. “We believe that this technology, when constructed in future helmets and bumpers, could reduce or even prevent many of the blunt-force injuries we see today.”

Gif created from video courtesy of UT Austin. Infographic courtesy of UTA.