Elliptical acoustic black holes for flexural wave lensing in plates

A metamaterial consisting of an acoustic black hole plate with local resonators for broadband vibration reduction

“…These include spiral ABHs for beam terminations [10,11], periodic ABHs embedded in straight [12] and circular beams [13], ABHs on elliptical plates [14], double-leaf ABHs in plates [12,15], ring-shaped ABHs for vibration isolation [16,17] and annular ABHs for cylindrical shells [18][19][20]. It is worth mentioning that the ABH effect has been also investigated for wave manipulation (see e.g., [21][22][23][24][25] among others), though this topic is out of the scope of this paper.…”

Progress and applications of acoustic black holes

“…近年来, 利用该原理完成了二维薄板上的不同二维声学黑洞波动能量调控工作. Deng 等人 [47] 提出了一种椭圆声学黑洞作为聚焦平板弯曲波的可调谐透镜, 研究发现, 椭圆声学黑洞的中心厚度、椭圆声学 黑洞阶数和偏心距能够影响弯曲波汇聚(图 4(a)), 同时指出将多个椭圆声学黑洞排列成一排有助于弯曲波集中在 远离透镜的区域. Huang 等人 [28]…”

Low-frequency sound radiation characteristics of imperfect acoustic black hole in thin plate

“…7,8 As research progresses further, the research object is extended from one-dimensional (1D) ABH beams and two-dimensional (2D) ABH plates to double-leaf ABH, [9][10][11] periodic tunnelled ABH plates, 12 periodic nested ABH structures, 13 annular ABHs inside a cylindrical shell, 14 2D circular ABH-based dynamic vibration absorber add-on structures attached to the benchmark plate 15 and elliptical ABHs similar to a tunable lens. 16 It was discovered that the combination of ABH indentation and damping layers resulted in excellent vibration and noise reduction performance. 17,18 Placing the damping layer at the tip of a 1D ABH or at the centre of a 2D ABH yields the most significant vibration-reduction effect.…”