Total conversion between the longitudinal and transverse waves by ultrathin elastic metamaterials with anisotropic resonances

Abstract

In this work, total conversions between longitudinal and transverse modes are achieved within an elastic metamaterial plate with thickness two orders smaller than the wavelength. The ultrathin metamaterial plate consists of an array of anisotropic dipolar resonators obliquely oriented, which can transfer the longitudinal movement into the transverse one, or vice versa, accounting for this effect. A mass-spring model is developed to depict analytically the mode conversion with a quantitative agreement with the simulation. The conversion rate of the metamaterial plate remains above 95% in varying solids, showing good adaptability in practical applications.

Mode conversions for elastic waves transmitted and reflected by ultrathin elastic metamaterial plates with anisotropic resonances

“…[21][22][23] However, reliance on the Fabry-Pérot resonance [18][19][20]24,25) or phase gradient 22,26) makes the size of the conversion devices of the same order as the working wavelength. Very recently, Wang et al proposed a new method 27) that did not use the effective elastic parameters or phase gradient. They use the anisotropic dipolar resonances [28][29][30][31][32] to generate sufficiently strong oblique displacements and consequently couple the P and S waves.…”

“…When the resonators are embedded in a solid background, we have to consider the conversions for both reflected and transmitted waves. The reflected system 27) can be regarded as a limit case, where half of the solid background is replaced by free space. The transitions from a general system to a limited case are also investigated in this work.…”

“…1(a), is composed of a steel cylinder coated with a layer of elliptical rubber embedded in an epoxy matrix. 27) The parameters of the materials used are 7900 kg m , q The units are arranged in a square lattice, and the band structure is plotted in Fig. 1(b).…”

“…Only part of the P wave can be converted into an S wave and total conversion is impossible in this transmitter system. But for a reflected system, as studied in Ref 27,. total conversion can be achieved.…”

Complete mode conversion between longitudinal and transverse waves by an elastic metamaterial slab with a double-scatterer structure

“…n recent years, the rise of elastic metamaterials has provided a new means for elastic wave manipulation, [1][2][3][4][5] which has attracted wide attention from researchers. The wave control of metamaterial mainly focuses on the amplitude, [6][7][8] phase [8][9][10][11][12][13] and polarization mode [14][15][16][17][18][19][20][21][22][23][24][25] of elastic wave. Among them, the conversion of the wave polarization mode is an interesting topic.…”