Tunable polarization bandgaps and elastic wave transmission in anisotropic origami metamaterials

Origami metamaterials have exhibited many extraordinary properties due to diversified configurations and excellent deformability, and widely exist in aerospace, civil engineering and other fields. This paper systematically studies elastic waves propagation characteristics of origami metamaterials in Bloch wave framework. Specifically, three-dimensional (3D) thin-shell elements are introduced to describe the continuous model of the origami structure. Through mode analysis and transmission spectrum, the underlying mechanisms that induce polarization bandgaps (BGs) can be demonstrated. The results indicate that the structure has two dominant polarization modes, shear-like polarization mode and coupling modes of longitudinal-like polarization and flexural-like polarization, which manifest the partial stopbands owing to the polarization of vibration modes. In particular, the unusual polarization transition from longitudinal to shear modes along iso-frequency contours occurs on account of extreme anisotropy of origami metamaterials, where the normal stiffness is less than shear stiffness in a certain direction. Besides, by tuning significant parameters of lattice configuration and size, customized polarization BGs characteristic with broad frequency domain can be realized, and propagation of elastic waves be controlled in metastructure. This work provides a new thought for the design of advanced materials and the manipulation of wave motion, which has potential in elastic wave functional devices with unique properties.