At the Cockrell School of Engineering at The University of Texas, researchers have developed a new energy-absorbing structure that follows the honeycomb structure pattern. The design, called negative stiffness (NS) honeycombs, is proved to withstand blunt impact and provide repeated protection from multiple impacts.
Improved honeycomb structure (Source: CockrellSchool)
Existing honeycomb technology, which can be found in automobiles and aircraft, features insular panels of repeating, hexagonal-shaped cells with different sizes and configurations. These conventional honeycombs, however, lose their protective properties in just a single impact because of the plastic buckling – not returning to their original shape once a compression is absorbed.
This is what NS sets apart from the conventional honeycomb. What was done by the researchers is to design a cell geometry that can buckle elastically rather than plastically, providing resilience to recover their energy-absorbing shape and properties after impact.
Improved honeycomb structure (Source: University of Texas)
A prototype was manufactured by the researchers which has cell dimensions of 3.5 inches. It has a force threshold level of 200 Newtons, but can absorb a 100 mph fastball in 0.03 seconds. It was made from nylon using selective laser sintering for experimentation.
The technology, once perfected, is useful in the automotive and military industry for protective hardware