基于梯度折射率材料的声偏转器研究
发布时间：2018-08-06 20:31
【摘要】：近些年来,声学人工材料逐渐成为一个研究热点,其中具有梯度折射率的非均匀介质的声波操控问题也得到广泛关注。类似于光学梯度透镜操控光波,声学梯度透镜也可以对声波进行聚焦,由于其在声波操控领域的作用,相关的研究取得了显著的进展。实现声学梯度透镜的一种有效的方法就是利用声子晶体,来调控材料的折射率分布。这种方法的优势在于可避免使用共振单元,有助于拓展工作带宽,并减少声能的损耗。声学梯度透镜的发展证明了声学梯度材料在声波操控方面的潜力,也对其他类型声学器件的设计与应用有很大的推动作用。声波的偏转也是一种重要的操控方式,对宽频声波的全向性偏转操控将具有重要研究意义,并有望在噪声控制、声学成像等领域实现其应用。本文从等效参数理论出发,根据声波偏转2π以下角度时符合的一系列近似条件,提出了基于声学梯度折射率材料的声波偏转器的设计理论,并利用一种可调控等效折射率的声子晶体单元结构加以实现,构建出了一种声偏转器的实际结构。此结构中没有共振单元,因此对宽频有效,而且具有全向性。数值计算证明,这种声偏转器结构可以对沿任意角度入射的声波进行偏转,使之按照预设的轨迹进行传播,并沿预定角度出射。本文分为以下几个部分。第一章是绪论部分,介绍了声子晶体、声学超常材料和声梯度材料的研究背景及其最新研究进展。第二章实理论背景,介绍了伊顿透镜及其近似方法,以及等效参数理论。第三章,根据本文提出的模型的一些近似条件,提出一种通过结构操控等效折射率的方法,并对梯度折射率结构和声子晶体结构的声偏转器进行仿真计算,用有限元模拟对三个特殊偏转角度的梯度折射率结构和声子晶体结构分别做了仿真计算,验证了这种方法的可行性。第四章,利用上一章中提出的声子晶体结构声偏转器的设计方法,制作出声偏转器样品,置于波导板中间模拟二维情况,通过测量波导板间的声场,利用插值算法画出声压分布图,进一步验证这种声偏转器的可行性。第五章,给出了工作总结和对今后的展望。
[Abstract]:In recent years, acoustic artificial materials have gradually become a hot spot of research. Acoustic manipulation in heterogeneous media with gradient refractive index is also widely concerned. Similar to optical gradient lenses, acoustic gradient lenses can also focus on sound waves. Due to their role in the field of acoustic manipulation, related research is taken. An effective way to realize the acoustic gradient lens is to use the phononic crystal to regulate the refractive index distribution of the material. The advantage of this method is to avoid the use of the resonant unit, to expand the bandwidth of the work, and to reduce the loss of the sound energy. The development of the acoustic gradient lens proves the acoustic gradient material in sound. The potential of wave manipulation also plays an important role in the design and application of other types of acoustic devices. The deflection of sound waves is also an important mode of manipulation. The omnidirectional deflection manipulation of the broadband sound wave will be of great significance, and it is expected to be applied in the field of noise control, acoustic imaging and other fields. This paper from the equivalent parameters In theory, based on a series of approximate conditions when the sound wave deflects below 2 pi angles, the design theory of acoustic deflector based on acoustic gradient refractive index material is proposed, and a sound phononic unit structure which can control the equivalent refractive index is realized, and the actual structure of a kind of acoustic deflector is constructed. The resonant unit is effective and omnidirectional. The numerical calculation shows that the structure of the acoustic deflector can deflect the sound waves incident at any angle, propagate it in accordance with the predetermined trajectory and go out along the predetermined angle. This paper is divided into the following parts. The first chapter is the introduction part, which introduces the phononic crystal and the sound. The research background and the latest research progress of supernormal materials and acoustic gradient materials. The second chapter real theory background, introduce the Eaton lens and its approximate method, and the equivalent parameter theory. In the third chapter, according to some approximate conditions of the model proposed in this paper, a method of manipulating the equivalent refractive index through the structure is proposed, and the gradient index rate is applied to the gradient index. The structure and phononic crystal structure of the acoustic deflector are simulated. The finite element simulation is used to simulate the gradient index structure and the phononic structure of three special deflection angles. The feasibility of this method is verified. The fourth chapter makes use of the design method of the phononic crystal structure acoustic deflector proposed in the last chapter. The sample of the acoustic deflector is placed in the middle of the waveguide plate to simulate the two-dimensional situation. By measuring the sound field between the waveguide plates, the interpolation algorithm is used to draw the sound pressure distribution map, and the feasibility of the acoustic deflector is further verified. In the fifth chapter, the summary of the work and the future prospect are given.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O735
，
本文编号：2168905
[Abstract]:In recent years, acoustic artificial materials have gradually become a hot spot of research. Acoustic manipulation in heterogeneous media with gradient refractive index is also widely concerned. Similar to optical gradient lenses, acoustic gradient lenses can also focus on sound waves. Due to their role in the field of acoustic manipulation, related research is taken. An effective way to realize the acoustic gradient lens is to use the phononic crystal to regulate the refractive index distribution of the material. The advantage of this method is to avoid the use of the resonant unit, to expand the bandwidth of the work, and to reduce the loss of the sound energy. The development of the acoustic gradient lens proves the acoustic gradient material in sound. The potential of wave manipulation also plays an important role in the design and application of other types of acoustic devices. The deflection of sound waves is also an important mode of manipulation. The omnidirectional deflection manipulation of the broadband sound wave will be of great significance, and it is expected to be applied in the field of noise control, acoustic imaging and other fields. This paper from the equivalent parameters In theory, based on a series of approximate conditions when the sound wave deflects below 2 pi angles, the design theory of acoustic deflector based on acoustic gradient refractive index material is proposed, and a sound phononic unit structure which can control the equivalent refractive index is realized, and the actual structure of a kind of acoustic deflector is constructed. The resonant unit is effective and omnidirectional. The numerical calculation shows that the structure of the acoustic deflector can deflect the sound waves incident at any angle, propagate it in accordance with the predetermined trajectory and go out along the predetermined angle. This paper is divided into the following parts. The first chapter is the introduction part, which introduces the phononic crystal and the sound. The research background and the latest research progress of supernormal materials and acoustic gradient materials. The second chapter real theory background, introduce the Eaton lens and its approximate method, and the equivalent parameter theory. In the third chapter, according to some approximate conditions of the model proposed in this paper, a method of manipulating the equivalent refractive index through the structure is proposed, and the gradient index rate is applied to the gradient index. The structure and phononic crystal structure of the acoustic deflector are simulated. The finite element simulation is used to simulate the gradient index structure and the phononic structure of three special deflection angles. The feasibility of this method is verified. The fourth chapter makes use of the design method of the phononic crystal structure acoustic deflector proposed in the last chapter. The sample of the acoustic deflector is placed in the middle of the waveguide plate to simulate the two-dimensional situation. By measuring the sound field between the waveguide plates, the interpolation algorithm is used to draw the sound pressure distribution map, and the feasibility of the acoustic deflector is further verified. In the fifth chapter, the summary of the work and the future prospect are given.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O735
，
本文编号：2168905
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