【摘要】：近些年來,聲學(xué)人工材料逐漸成為一個(gè)研究熱點(diǎn),其中具有梯度折射率的非均勻介質(zhì)的聲波操控問題也得到廣泛關(guān)注。類似于光學(xué)梯度透鏡操控光波,聲學(xué)梯度透鏡也可以對(duì)聲波進(jìn)行聚焦,由于其在聲波操控領(lǐng)域的作用,相關(guān)的研究取得了顯著的進(jìn)展。實(shí)現(xiàn)聲學(xué)梯度透鏡的一種有效的方法就是利用聲子晶體,來調(diào)控材料的折射率分布。這種方法的優(yōu)勢(shì)在于可避免使用共振單元,有助于拓展工作帶寬,并減少聲能的損耗。聲學(xué)梯度透鏡的發(fā)展證明了聲學(xué)梯度材料在聲波操控方面的潛力,也對(duì)其他類型聲學(xué)器件的設(shè)計(jì)與應(yīng)用有很大的推動(dòng)作用。聲波的偏轉(zhuǎn)也是一種重要的操控方式,對(duì)寬頻聲波的全向性偏轉(zhuǎn)操控將具有重要研究意義,并有望在噪聲控制、聲學(xué)成像等領(lǐng)域?qū)崿F(xiàn)其應(yīng)用。本文從等效參數(shù)理論出發(fā),根據(jù)聲波偏轉(zhuǎn)2π以下角度時(shí)符合的一系列近似條件,提出了基于聲學(xué)梯度折射率材料的聲波偏轉(zhuǎn)器的設(shè)計(jì)理論,并利用一種可調(diào)控等效折射率的聲子晶體單元結(jié)構(gòu)加以實(shí)現(xiàn),構(gòu)建出了一種聲偏轉(zhuǎn)器的實(shí)際結(jié)構(gòu)。此結(jié)構(gòu)中沒有共振單元,因此對(duì)寬頻有效,而且具有全向性。數(shù)值計(jì)算證明,這種聲偏轉(zhuǎn)器結(jié)構(gòu)可以對(duì)沿任意角度入射的聲波進(jìn)行偏轉(zhuǎn),使之按照預(yù)設(shè)的軌跡進(jìn)行傳播,并沿預(yù)定角度出射。本文分為以下幾個(gè)部分。第一章是緒論部分,介紹了聲子晶體、聲學(xué)超常材料和聲梯度材料的研究背景及其最新研究進(jìn)展。第二章實(shí)理論背景,介紹了伊頓透鏡及其近似方法,以及等效參數(shù)理論。第三章,根據(jù)本文提出的模型的一些近似條件,提出一種通過結(jié)構(gòu)操控等效折射率的方法,并對(duì)梯度折射率結(jié)構(gòu)和聲子晶體結(jié)構(gòu)的聲偏轉(zhuǎn)器進(jìn)行仿真計(jì)算,用有限元模擬對(duì)三個(gè)特殊偏轉(zhuǎn)角度的梯度折射率結(jié)構(gòu)和聲子晶體結(jié)構(gòu)分別做了仿真計(jì)算,驗(yàn)證了這種方法的可行性。第四章,利用上一章中提出的聲子晶體結(jié)構(gòu)聲偏轉(zhuǎn)器的設(shè)計(jì)方法,制作出聲偏轉(zhuǎn)器樣品,置于波導(dǎo)板中間模擬二維情況,通過測(cè)量波導(dǎo)板間的聲場(chǎng),利用插值算法畫出聲壓分布圖,進(jìn)一步驗(yàn)證這種聲偏轉(zhuǎn)器的可行性。第五章,給出了工作總結(jié)和對(duì)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.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：O735
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本文編號(hào)：2168905