Design and compressive behaviors of the gradient re-entrant origami honeycomb metamaterials

In recent years, origami honeycomb metamaterials have garnered extensive attention from researchers. Reentrant origami honeycomb metamaterials exhibit excellent mechanical performances by virtue of lightweight, high -energy -absorbing characteristics and diverse configurations. In this study, the gradient re-entrant origami honeycomb metamaterials are designed by changing significant geometric parameters. To investigate the effects of geometric parameters variations on compressive behaviors, the theoretical analysis model of the re-entrant origami honeycomb is built to predict the compression stress under low -velocity and high -velocity impact. Subsequently, the energy absorption of the uniform re-entrant origami honeycomb (UROH), the gradientthickness re-entrant origami honeycombs (GTROHs) and the gradient -angle re-entrant origami honeycomb (GAROHs)are investigated under different compression velocities. The impact resistances of UROH, GTROHs and GAROHs are discussed systematically. By adjusting the gradient distribution of thickness, the deformation modes and Poisson's ratio curves of the structure could be altered. Furthermore, under the high -velocity impact, the specific energy absorption (SEA) of the unidirectionally negative GTROH is increased by 36% than that of UROH at the strain of 0.29. The SEA of the unidirectionally positive GTROH is higher by 14.4% than that of UROH at the strain of 0.8. In addition, the unidirectionally positive GTROH exhibits better impact resistance performance than UROH by comparing the peak stress and SEA value under different compression velocities. This study is expected to provide the new route for designing advanced origami -inspired honeycomb structures and improving buffer protection devices.