弹性超表面驱动弯曲 Lamb 波源幻觉装置

40 浏览量更新于2024-08-31 收藏 1.1MB PDF 举报

"源错觉装置在柔性Lamb波弹性元表面的应用研究" 本文探讨了源错觉设备在利用弹性元表面操控柔性Lamb波领域的创新技术。Lamb波是一种在薄板或层状结构中传播的波动，特别是在无损检测和超声成像等应用中具有重要意义。近期，电磁隐形衣（metasurfaces）的概念被用于实现对电磁波的类似操作，即创造局部区域内的波前控制。作者Yongquan Liu、Zixian Liang、Fu Liu、Owen Diba、Alistair Lamb和Jensen Li来自英国伯明翰大学物理与天文学学院以及中国深圳大学电子科学与技术学院，他们在此研究中提出了一个突破性的方法，利用弹性元表面设计出能实现灵活波源操作的设备。这种技术的独特之处在于，它克服了传统变换方法中形式不变性的问题，特别适用于处理柔性材料中的波动。实验展示了源错觉装置如何实现波源位置的移动、形状变换以及分裂，这些操作都是在紧凑且易于实施的弹性元表面上完成的。结果表明，这些效果具有宽频带特性，对源位置的变化表现出良好的鲁棒性，与数值模拟和胡伊根斯-菲涅尔理论的预测高度一致。这种方法对于非破坏性检测、高分辨率超声成像等应用具有巨大的潜力，因为它提供了对波动行为的精确控制，有助于提高测量精度并减少对测试环境的影响。这项研究不仅扩展了弹性元表面在操控波动领域的应用范围，也为未来开发新型的声学隐身设备和精确波操控技术打下了坚实的基础。通过源错觉装置，研究人员可以设计出更高效、更具适应性的柔性波管理工具，这对于推动相关行业如材料科学、航空航天以及医疗诊断的发展具有深远意义。"

Source Illusion Devices for Flexural Lamb Waves Using Elastic Metasurfaces

Yongquan Liu,

Zixian Liang,

Fu Liu,

Owen Diba,

Alistair Lamb,

and Jensen Li

1,*

School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom

College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060, China

(Received 10 January 2017; published 21 July 2017)

Inspired by recent demonstrations of metasurfaces in achieving reduced versions of electromagnetic

cloaks, we propose and experimentally demonstrate source illusion devices to manipulate flexural waves

using metasurfaces. The approach is particularly useful for elastic waves due to the lack of form invariance

in usual transformation methods. We demonstrate compact and simple-to-implement metasurfaces for

shifting, transforming, and splitting a point source. The effects are measured to be broadband and robust

against a change of source positions, with agreement from numerical simu lations and the Huygens-Fresnel

theory. The proposed method is potentially useful for applications such as nondestructive testing,

high-resolution ultrasonography, and advanced signal modulation.

DOI: 10.1103/PhysRevLett.119.034301

The ability to make objects invisible has captured our

imagination since ancient times and has become reachable

very recently due to the appearance of metamaterials [1]

together with transformation optics [2–5]. A family of more

general illusion effects has also been established based on

the transformation approach. Either scattering [6,7] or

source radiation [8] can be transformed to prescribed target

patterns. Furthermore, the transformation approach has

been extended to control acoustic waves [9–11] and heat

flows [12–14]. Although some elastic cloaks have been

studied and designed with approximations [15,16], the

transformation method, together with elastic metamaterials

[17–22], is nonuniversal to manipulate elastic waves, as the

governing equation in elastodynamics (i.e., the Navier

equation) cannot keep its form under a general coordinate

transformation [23], unless further approximations [24] are

applied or the proposed Willis media [25] can be realized

and employed with a complex cross-coupling response. It

makes the application of the transformation approach on

elastic waves nontrivial and more generic illusion appli-

cations, which may use negative-index metamaterials with

unavoidable loss and fabrication issues, very challenging.

On the other hand, the recently proposed metasurface

[26–33], a kind of artificial sheet material with subwave-

length-scaled patterns and thickness, can modulate wave

fronts on demand through specific boundary conditions.

The metasurface approach shows the simplicity in fabri-

cation with a low-loss, compact form factor but without

losing the extreme functionality of bulk metamaterials. It

has already been demonstrated as an effective way to

manipulate wave fronts in both optics and acoustics,

including generating an anomalous refraction or reflection,

arbitrary surface plasmon profiles, high-efficiency holo-

grams [26–32], and even an ultrathin invisibility cloak

[33,34], which is a simplified version of a carpet cloak

originally using bulk metamaterials in the transformation

approach [35]. Therefore, the extension of metasurfaces to

elastic waves is expected to be very effective to demonstrate

nontrivial wave phenomena, which associate with richer

physics [20–22] due to its more degrees of freedom than

acoustic and electromagnetic counterparts and a wide range

of potential applications in nondestructive testing, medical

ultrasonography, and earthquake resistance in civil engi-

neering [18,36–40]. Until very recently, Zhu and

Semperlotti [41] have presented the first experimental

demonstration of elastic metasurfaces to achieve the

anomalous refraction of guided waves in solids, based

on a “cross-polarization” conversion (from symmetric S

antisymmetric A

mode) with a transmission efficiency

around 18%, comparing to the theoretical maximum

efficiency 25% in the case of electromagnetic waves

[42,43]. A higher transmission efficiency, together with a

suitable design framework, will be an enabling key to a

much wider range of applications of elastic metasurfaces.

In this Letter, we develop a theoretical framework and

experimental realization of source illusion devices using

elastic metasurfaces. Our approach requires neither the

fore-mentioned form invariance of elastodynamics nor bulk

metamaterials with negative indices yet allows us to

demonstrate a series of all-angle elastic illusion effects.

Figure 1(a) shows a schematic diagram illustrating the

design strategy. The target wave profile, living in the virtual

space, is described by its phase profile ϕ

tar

ðx; yÞ [left-hand

side of Fig. 1(a)]. At the moment, we neglect the con-

tribution of the amplitude profile for simplicity. Suppose

that we have an original source, with a wave field

characterized by its phase ϕ

ori

ðx; yÞ, and a ring-type

metasurface with the phase discontinuity of ϕ

tar

− ϕ

ori

being evaluated at the location of the metasurface, will turn

this original incident field into an arbitrary target profile

[right-hand side of Fig. 1(a)]. A photograph of a metasur-

face sample is shown in Fig. 2(a) as well. By doing this, an

observer outside the metasurface (the black dashed circle)

finds the same target field pattern in the physical space as

PRL 119, 034301 (2017)

PHYSICAL REVIEW LETTERS

week ending

21 JULY 2017

下载后可阅读完整内容，剩余5页未读，立即下载

weixin_38674992

粉丝: 7
资源: 963

弹性超表面驱动弯曲 Lamb 波源幻觉装置

Particle_illusion_for_AE CS4

Illusion_Wizzard

Opticall Illusion Wallpaper for New Tab-crx插件

Particle Illusion for AECS4插件

IllusionBBS:非官方 Illusion BBS v3.0 (DOS Pascal Source)

Illusion3.0

Particle Illusion

Illusion_Deformers

optical illusion test

illusion粒子效果教程

最新资源