Analytical modeling and design of negative stiffness honeycombs

Negative stiffness honeycombs (NSHs) have multiple advantages compared to traditional honeycomb structures. These advantages include recoverable elastic buckling, shock absorption, and vibration isolation. As a result, NSHs have great potential in applications such as acoustic wave guiding, shape morphing, design of impact-protection devices and robotic grippers. In this paper, we present a design methodology for metamaterial consisting of negative stiffness beams assembled in a honeycomb structure. Based on analytical results, our methodology allows designing NSH mesostructures with predetermined buckling sequence. An NSH prototype was designed based on our algorithm and fabricated using a 3D printer with a nylon filament. The validity of our approach was experimentally verified by performing displacement controlled compression force measurements. Our methodology gives the ability to design NSH mesostructures with desired force-displacement characteristics.