Experimental analysis on nonlinear elastic wave characteristics of metallic origami cylinder

Abstract

This paper presents an experimental investigation on the origami patterned cylinder made of Tachi-Miura Polyhedron (TMP) unit cell. The unit cell shows strain-softening behavior under compression load. To analyze the effect of nonlinear behavior on the elastic wave propagation in TMP cylinder, fabrication of metallic origami cylinder and impact test were conducted. The thin metallic structure was fabricated using the vacuum bag method. The pressure was applied evenly to the aluminum facets, which have compliant hinges that behave like torsional springs. The first unit cell of the cylinder structure was connected to the dynamic shaker and the pulse load was applied. To measure the dynamic behavior of unit cells during elastic wave propagation, the stereo pattern recognition (SPR) camera system was employed. The experimental result shows that the compressive wave, induced by impact load, was attenuated due to the nonlinear characteristics of the TMP unit cell. Furthermore, the tensile wave, which emerged later, arrived first on the last unit cell. It means that the tensile wave overtook the compressive wave. The speed of the elastic wave is affected by the stiffness of the structure. Based on the strain-softening behavior of the TMP unit cell, the compressive wave is slower than the tensile wave. It induced the attenuation of compressive impact and overtaking of tensile elastic wave. We can expect that this nonlinear characteristic of the origami-based structure can be applied to the shock mitigation structure.