Two-dimensional traditional acoustic black hole (ABH) embedded in the plate has been recognized as a highly effective tool for wave energy harvesting, which enables wave trajectories to converge into a confined area. Traditional ABH is a rotational symmetrical circular indentation, and the residual thickness platform is always located in the center. This type of ABH has been widely investigated in previous study. However, the discussion on the structure configuration and layout of the residual thickness platform is rare. In this paper, two types of unconventional ABHs embedded in the plate are proposed and studied, namely “Heteromorphic ABH” and “Eccentric ABH,” which represent that the shape of indentation is no longer a circle and the inner platform is not located in the center, respectively. These unconventional ABHs can also converge the flexural wave, but the focalization phenomenon is obviously distinct from that of the traditional ABH. The converging performances are characterized through the ray-tracing method based on the geometrical acoustic method. The validation of calculated results is conducted using the finite element simulation. Moreover, the effects of ABH geometric parameters are investigated in detail. The unconventional ABH demonstrates the multiplicity in structure and shows the potential of the flexible manipulation for flexural waves.
PelatAGautierFConlonSC, et al. The acoustic black hole: a review of theory and applications. J Sound Vib2020; 476: 115316.
2.
DengJGuaschOZhengL, et al. Semi-analytical model of an acoustic black hole piezoelectric bimorph cantilever for energy harvesting. J Sound Vib2021; 494: 115790.
3.
JiHLiangYQiuJ, et al. Enhancement of vibration based energy harvesting using compound acoustic black holes. Mech Syst Signal Process2019; 132: 441–456.
4.
ZhaoLConlonSCSemperlottiF. An experimental study of vibration based energy harvesting in dynamically tailored structures with embedded acoustic black holes. Smart Mater Struct2015; 24: 065039.
5.
JiHWangNZhangC, et al. A vibration absorber based on two-dimensional acoustic black holes. J Sound Vib2021; 500: 116024.
6.
TangLGaoNXuJ, et al. A light-weight periodic plate with embedded acoustic black holes and bandgaps for broadband sound radiation reduction. J Acoust Soc Am2021; 150: 3532–3543.
7.
MaLChengL. Numerical and experimental benchmark solutions on vibration and sound radiation of an acoustic black hole plate. Appl Acoust2020; 163: 107223.
8.
WangXJiHQiuJ, et al. Wavenumber domain analyses of vibro-acoustic decoupling and noise attenuation in a plate-cavity system enclosed by an acoustic black hole plate. J Acoust Soc Am2019; 146: 72–84.
9.
WangXLiuXTaiJ, et al. A novel method of reducing the acoustic emission wave reflected by boundary based on acoustic black hole. Ultrasonics2019; 94: 292–304.
10.
ZhuHSemperlottiF. Phononic thin plates with embedded acoustic black holes. Phys Rev B2015; 91: 104304.
11.
ZhuHSemperlottiF. Two-dimensional structure-embedded acoustic lenses based on periodic acoustic black holes. J Appl Phys2017; 122: 065104.
12.
NingLWangYWangY. Active control of a black hole or concentrator for flexural waves in an elastic metamaterial plate. Mech Mater2020; 142: 103300.
13.
KrylovVV. Overview of localised flexural waves in wedges of power-law profile and comments on their relationship with the acoustic black hole effect. J Sound Vib2020; 468: 115100.
14.
HuangWJiHQiuJ, et al. Wave energy focalization in a plate with imperfect two-dimensional acoustic black hole indentation. J Vib Acoust2016; 138: 061004.
15.
KrylovVVTilmanFJBS. Acoustic “black holes” for flexural waves as effective vibration dampers. J Sound Vib2004; 274: 605–619.
16.
HuangWTaoCJiH, et al. Enhancement of wave energy dissipation in two-dimensional acoustic black hole by simultaneous optimization of profile and damping layer. J Sound Vib2021; 491: 115764.
17.
HeMDingQ. Data-driven optimization of the periodic beam with multiple acoustic black holes. J Sound Vib2021; 493: 115816.
18.
McCormickCAShepherdMR. Design optimization and performance comparison of three styles of one-dimensional acoustic black hole vibration absorbers. J Sound Vib2020; 470: 115164.
19.
DengJZhengLGuaschO, et al. Gaussian expansion for the vibration analysis of plates with multiple acoustic black holes indentations. Mech Syst Signal Process2019; 131: 317–334.
20.
BowyerEPKrylovVV. Experimental study of sound radiation by plates containing circular indentations of power-law profile. Appl Acoust2015; 88: 30–37.
21.
ZhouTTangLJiH, et al. Dynamic and static properties of double-layered compound acoustic black hole structures. Int J Appl Mech2017; 9: 1750074.
22.
ZhouTChengL. Planar swirl-shaped acoustic black hole absorbers for multi-directional vibration suppression. J Sound Vib2022; 516: 116500.
23.
DengJZhengLGuaschO. Elliptical acoustic black holes for flexural wave lensing in plates. Appl Acoust2021; 174: 107744.
24.
HuangWJiHQiuJ, et al. Analysis of ray trajectories of flexural waves propagating over generalized acoustic black hole indentations. J Sound Vib2018; 417: 216–226.
25.
ClimenteATorrentDSanchez-DehesaJ. Gradient index lenses for flexural waves based on thickness variations. Appl Phys Lett2014; 105: 064101.
26.
JiHZhaoXWangN, et al. A circular eccentric vibration absorber with circumferentially graded acoustic black hole features. J Vib Acoust2022; 144: 1–35.
27.
GantiSSLiuTSemperlottiF. Topological edge states in phononic plates with embedded acoustic black hole. J Sound Vib2020; 466: 115060.
28.
KrylovVV. Transmission of Rayleigh waves through smooth large-scale surface irregularities. Sov Phys: Acoust1988; 34: 613–618.
29.
KrylovVV. Conditions for validity of the geometrical-acoustics approximation in application to waves in an acute-angle solid wedge. Sov Phys: Acoust1989; 35: 176–180.
30.
YanSLomonosovAMShenZ. Numerical and experimental study of Lamb wave propagation in a two-dimensional acoustic black hole. J Appl Phys2016; 119: 214902.
31.
LomonosovAMYanSHanB, et al. Orbital-type trapping of elastic Lamb waves. Ultrasonics2016; 64: 58–61.
32.
JiHHanBChengL, et al. Frequency attenuation band with low vibration transmission in a finite-size plate strip embedded with 2D acoustic black holes. Mech Syst Signal Process2022; 163: 108149.
33.
KarlosAElliottSJCheerJ. Higher-order WKB analysis of reflection from tapered elastic wedges. J Sound Vib2019; 449: 368–388.
34.
PierceAD. Physical interpretation of the WKB or eikonal approximation for waves and vibrations in inhomogeneous beams and plates. J Acoust Soc Am1970; 48: 275–284.
35.
CaoSLeeHPLimKM. Estimation of wave reflection coefficient by semi-analytical method in an acoustic black hole beam. Int J Appl Mech2020; 12: 20500040.
36.
ClimenteATorrentDSanchez-DehesaJ. Omnidirectional broadband insulating device for flexural waves in thin plates. J Appl Phys2013; 114: 214903.
37.
MironovMA. Propagation of a flexural wave in a plate whose thickness decreases smoothly to zero in a finite interval. Sov Phys: Acoust1988; 34: 318–319.
