Deflecting flexural wave with high transmission by using pillared elastic metasurface

Abstract

This paper proposes an innovative and simple elastic metasurface, which is one kind of ultrathin metamaterial, to abnormally deflect normally and obliquely incident flexural waves. In particular, negative refraction of flexural wave is also realized. The proposed metasurface can support high transmission and full phase control for transmitted waves. The metasurface is composed of three-dimensional (3D) functional units which are combined with multiple slender pillars for phase shift accumulation. The slots are filled in the 3D functional units to avoid coupling between adjacent functional units. Firstly, based on the generalized Snell’s law, the metasurface in the sub-wavelength regime is theoretically designed. Secondly, the deflecting functionality of the metasurface for incident flexural waves is numerically demonstrated. Finally, the deflecting functionality is verified by the corresponding experiments. The proposed metasurface has a great application potential in many fields, such as ultrasonic detection, energy harvesting, and vibration control.

Flexural wave absorption by lossy gradient elastic metasurface

“…For the six piezoelectric patches in the middle, the amplified voltage is two times of that for the two outer piezoelectric patches. It should be pointed out that for different excitation frequencies, one need to adjust the distance between piezoelectric patches to generate a flexural wave Gaussian beam according to the phased array theory (Zhu et al, 2014b;Cao et al, 2018c). For example, in the central frequency of 600 Hz, the distance between piezoelectric plates is 2.5 times length of the piezoelectric patch width.…”

Disordered Elastic Metasurfaces

“…The slots are very small relative to the stretched width of the subunit. The little slot will lead to a very small flexural wave scattering, which will not affect the transmission amplitude and phase shift [27]. Therefore, the 3D subunit structure with the slot still can be equivalent to the corresponding 2D one.…”

Recent Advances in Non-Traditional Elastic Wave Manipulation by Macroscopic Artificial Structures

“…The designed refraction angles obtained by the numerical simulations were in excellent agreement with the analytical predictions (Figure 12b,c). An elastic MS that exploits local resonance of 3D column structures can support high transmission and full phase control to deflect flexural waves [150]. Elastic MSs can be applied to manipulate not only flexural waves but also Rayleigh and Love waves.…”