An impedance-mobility model of stacked membrane-type acoustic metamaterials

Abstract

Membrane-type acoustic metamaterials have been proven to exhibit high low-frequency transmission loss despite their small thickness and light weight. To date, analysis has focused primarily on experimental studies in plane-wave tubes and numerical modeling using finite element methods. These methods are inefficient when used for applications that require iterative changes to the structure of the material. In addition, high sound transmission loss with a single layer of such metamaterial only occurs in a narrow frequency range. To facilitate design and optimization of stacked membrane-type acoustic metamaterials, a computationally efficient dynamic model based on the impedance-mobility approach is proposed. Results are verified against a finite element model. Single and double layer transmission loss characteristics are compared. Wide-band high-transmission-loss acoustic metamaterials can be achieved by double layer membranes and using the proposed approach for optimization. The impedance-mobility approach is shown to be very efficient for modeling and optimization of such materials, compared against the conventional finite element approach.

Achieving Enhanced Sound Insulation through Micromembranes-Type Acoustic Metamaterials

“…Acoustic metamaterials (AMMs), as a family of macroscopic artificial composites, typically consist of many subwavelength-scaled structures arranged in a specific pattern so that they produce an optimized combination, not available in nature, of two or more responses to acoustic excitation [1]. In recent years, many acousticians have shown great interest in studying acoustic metamaterials [1][2][3][4][5] and have uncovered many new phenomena different from those associated with traditional acoustic materials [6][7][8][9][10][11][12][13].…”

A lightweight low-frequency sound insulation membrane-type acoustic metamaterial

“…Subsequently, a great many locally resonant sonic materials were investigated by many researchers, [3][4][5][6][7][8][9][10][11] and some achievements have been obtained, but seldom have these materials been used in engineering applications due to the heavy weight. Recently, the membrane-type acoustic metamaterials were proposed, [12][13][14][15][16][17][18] which had broadened the realm of elastic wave characteristics achievable by phononic crystals. By attaching an adjustable small mass block onto the membrane with clamped boundaries, a negative mass density can be obtained at a specific frequency band, thus realizing the total reflection of low-frequency sound and breaking the mass law.…”

“…By attaching an adjustable small mass block onto the membrane with clamped boundaries, a negative mass density can be obtained at a specific frequency band, thus realizing the total reflection of low-frequency sound and breaking the mass law. 12 The effects of the membrane and mass properties on the transmission loss have been investigated, [13][14][15][16][17][18] and the sound insulation at low frequencies can be tuned by varying the acoustic metamaterial structure. Layered on no-mass-attached membrane structures with negative mass density below a cut-off frequency have been demonstrated by Lee et al 19 Yao et al 20 pointed out that a rectangular solid waveguide with clamped boundary a Author to whom correspondence should be addressed.…”