基于声学人工材料的声功能器件研究

发布时间：2018-07-23 13:34

【摘要】：近十年来,声人工材料及其在声功能器件方面的应用一直受到了广泛的关注。声人工材料是指人工复合的具有自然界物质所不具备的超常声波传输特性的结构或者介质。声波在其中的传播特性除了会受到构成材料的影响,更与其几何结构有很大的关系。周期的或者其他特殊的微结构单元会对传输声波起到一定的调制作用,从而表现出各种奇特的物理现象,如负折射、自准直、超透射等。这些特殊的物理性质突破了传统声学理论的一些基础概念,为人们自由地调控声波提供了新的途径,也为新型声功能器件的开发提供了全新的思路和理念,在声隐身、声超透镜、集成声功能器件等诸多领域具有重要的应用前景。本文基于声人工材料提出了几种新型的声功能器件,并系统地对声波在其中的传播进行了理论数值研究和实验验证。这几种新型的声功能器件主要包括相位调控型声开关和声逻辑门,Fano共振型声传感器以及环形流场声子晶体中自准直声波的单向传输。第一章绪论部分主要回顾了本文相关的声人工材料的研究背景以及最新进展,并概述了本文研究工作的主要内容。第二章中,基于二维声子晶体中声波的自准直效应,提出了声开关及声逻辑门。该二维声子晶体的对角线方向的线缺陷起到3 dB分束器的作用,通过调整两输入声信号的相位可以控制输出端声波的幅值大小。在特殊的输入相位差下可以实现声开关以及声逻辑门的功能。通过仿真和实验研究,实现了与门、或门、异或门以及非门的基本逻辑门功能。并且由于自准直声波无衍射拓宽的特性,上述的基本逻辑门还可以互相级联以实现更多复杂的逻辑门,如与非门、或非门以及同或门。第三章中,基于零密度超材料,提出了一种波长尺度的可变型的声开关和声逻辑门。基本的逻辑门单元由一个三端口的声波导填入卷曲空间超材料组成,整个逻辑门尺寸大约为工作波长的0.82倍。由于零密度材料的特性,两入射声波可以在出射端以近乎可以忽略的相位延迟以及近乎不变的波阵面相互叠加,使出射声波的幅值可以通过调整输入相位差来控制。分别从理论和实验两方面实现了声逻辑与门、或门、异或门和非门。并且更多复杂的逻辑门以及逻辑运算,如与非门、或非门,“I1+I2×I3”等逻辑运算可以通过级联不同形状的基本逻辑门单元来实现。第四章中,实现了二维声子晶体中自准直声波的Fano共振。该Fano共振器由二维声子晶体中单层或多层的Z字形线缺陷以及两层同样呈Z字形排列的钢柱构成。研究发现构成Fano共振的连续态和离散态可以通过调整谐振器的结构参数来调控,这使得Fano共振的共振频率以及非对称线型的连续自由调控称为可能。由于Fano共振线型具有急剧变化的特点,其在声传感方面具有重要的应用。本章将该Fano共振应用到乙醇溶液中乙醇质量分数的探测中,并取得了很好的效果。第五章中,理论上实现了自准直声波的单向自准直传播。通过构造非对称的散射柱以及引入环形流场,分别打破系统的空间对称性和时间反转对称性,从而支持声波的单向传输。在一定频率范围内该单向声波还可以自准直传播,反向输入时输出声波的声能级相差可以达到30 dB。当该声子晶体的流场流速呈渐变分布时,自准直声波在其中的传播方向也会逐渐改变最终折返回入射界面,这种声路可设计的环形流场声子晶体为声波传输的调控提供了一种新的思路。第六章中,对全文进行了简单的总结以及对未来工作的展望。
[Abstract]:In the last ten years, acoustic artificial materials and their applications in acoustic functional devices have been widely concerned. Acoustic artificial material is a structure or medium with a complex transmission characteristic of a supernormal sound wave, which is not possessed by natural materials. The structure has a great relationship. Periodic or other special microstructural units will modulate the transmission sound wave, which shows a variety of strange physical phenomena, such as negative refraction, self collimation, ultra transmission, etc. these special physical properties break through some basic concepts of traditional acoustic theory and regulate sound freely for people. The wave provides a new way and provides new ideas and ideas for the development of a new acoustic function device. It has an important application prospect in many fields, such as acoustic stealth, acoustic hyperlens, integrated sound function device and so on. In this paper, several new acoustic function devices are proposed based on acoustic artificial materials, and the propagation of sound waves in it is systematically carried out. Theoretical numerical research and experimental verification are carried out. These new acoustic functions mainly include phase regulated sound switch and acoustic logic gate, Fano resonant acoustic sensor and unidirectional transmission of self collimated sound in the Phonon Crystal of annular flow field. The first chapter mainly reviews the research background of the related acoustic artificial materials. In the second chapter, based on the self collimation effect of acoustic wave in the two-dimensional phononic crystal, the sound switch and the acoustic logic gate are proposed in the second chapter. The line defect of the diagonal direction of the two-dimensional phononic crystal plays the role of the 3 dB beam splitter, and the output end can be controlled by adjusting the phase of the two input sound signal. The amplitude of sound wave. The function of sound switch and sound logic gate can be realized under special input phase difference. Through simulation and experimental study, the basic logic gate functions of the door, or gate, the gate, the gate and the non gate are realized. And the basic logic gates above can be cascaded to each other because of the characteristics of the non diffraction widening of the self collimation sound sound. To achieve more complex logic gates, such as NAND gate, or non gate, and the same or gate, the third chapter, based on zero density supermaterial, presents a wavelength scale variable sound switch and acoustic logic gate. The basic logic gate unit is composed of a three port acoustic waveguide filled with curled space supermaterial, and the whole logic gate size is about the work. 0.82 times of the wavelength. Due to the characteristics of zero density materials, the two incident sound wave can be overlapped with almost negligible phase delay and almost invariable wavefront at the ejection end. The amplitude of the acoustic wave can be controlled by the adjustment of the input phase difference. From the theoretical and experimental two aspects, the acoustic logic and the door, or gate, or different or different, are realized. The gate and the non gate. And more complex logic gates and logic operations, such as the non gate, or the non gate, the "I1+I2 x I3" and other logic operations can be realized by cascading the basic logic gate units with different shapes. In the fourth chapter, the self collimated sound waves in the two-dimensional phononic crystal are realized. The Fano resonator is single layer in the two-dimensional phononic crystal. It is found that the continuous and discrete states of the Fano resonance can be regulated by adjusting the structural parameters of the resonator, which makes the continuous free control of the resonance frequency of the Fano resonance and the continuous free regulation of the asymmetric line form as possible. Because of the Fano resonance line type, the Z resonance's continuous and discrete state can be regulated by the structure of a Z shaped steel column. In this chapter, the Fano resonance is applied to the detection of ethanol concentration in ethanol solution and has achieved good results in this chapter. In the fifth chapter, the unidirectional self collimation of self collimated sound waves is realized in theory. The asymmetric scattering column and the introduction of the annular flow field are constructed. The spatial symmetry of the system and the time reversal symmetry are broken to support the one-way transmission of sound waves. The one-way sound wave can also be propagated from the collimation in a certain frequency range. The acoustic energy level difference of the output sound wave can reach 30 dB. when the reverse input is used. When the flow velocity of the phononic crystal is gradually distributed, the self collimation sound wave is in it The direction of propagation will also gradually change and return to the incident interface. This sound circuit can provide a new way of thinking for the regulation of acoustic transmission. In the sixth chapter, a brief summary of the full text and the prospect of the future work are made.
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TB51

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