3D-printed programmable mechanical metamaterials for vibration isolation and buckling control

Vibration isolation performance at low-frequency ranges before resonance is a vital characteristic that conventional springs cannot exhibit. This paper introduces a novel zero Poisson’s ratio graded cylindrical metamaterial to fulfill two main goals: (1) vibration isolation performance in lowfrequency bands prior to resonance and (2) global buckling control of a long cylindrical tube. For this purpose, “soft and stiff” re-entrant unit cells with varying stiffness were developed. The cylindrical metamaterials were then fabricated using a multi-jet fusion HP three-dimensional (3D) printer. The finite element analyses (FEA) and experimental results demonstrate that the simultaneous existence of multi-stiffness unit cells leads to quasi-zero stiffness (QZS) regions in the forcedisplacement relationship of a cylindrical metamaterial under compression. They possess significant vibration isolation performance at frequency ranges between 10 and 30 Hz. The proposed multi-stiffness re-entrant unit cells also offer global buckling control of long cylindrical tubes (with a length to diameter ratio of 3.7). The simultaneous existence of multi-stiffness re-entrant unit cells provides a feature for designers to adjust and control the deformation patterns and unit cells’ densification throughout cylindrical tubes.