【摘要】：聲子晶體豐富的物理內(nèi)涵激發(fā)了大家的研究興趣,其豐富可調(diào)的色散關(guān)系使聲波在聲子晶體中具有多種獨特的傳播方式。本文對結(jié)構(gòu)聲表面波在表面聲子晶體中的操控進行研究,我們知道結(jié)構(gòu)聲表面波作為一種新型的表面波,近年來得到學術(shù)界的廣泛關(guān)注,它不僅具有表面波的特性,同時還具有自身的優(yōu)勢,許多表面波的物理現(xiàn)象都可以通過對結(jié)構(gòu)聲表面波的測量和分析進行研究。文中關(guān)于結(jié)構(gòu)聲表面波的研究對多功能集成聲學器件的設(shè)計具有一定指導意義。本文主要從以下幾個方面開展工作:首先,研究結(jié)構(gòu)聲表面波的色散關(guān)系受幾何參數(shù)的影響,發(fā)現(xiàn)在剛性板上刻較寬和較深的凹槽能得到局域性更好的結(jié)構(gòu)聲表面波。我們設(shè)計了刻有周期性凹槽的三維剛性板,得到了非常平坦的結(jié)構(gòu)聲表面波等頻色散線,利用等頻色散線的獨特形狀實現(xiàn)了結(jié)構(gòu)聲表面波的自準直傳輸,這將對于新型聲學器件的設(shè)計提供一定的理論指導。其次,通過一個45°楔型表面聲子晶體可以實現(xiàn)結(jié)構(gòu)聲表面波的直角轉(zhuǎn)彎及成像,所成像的半高寬為0.316λ。如若將兩楔型聲子晶體合并且引入一條線缺陷,則入射的準直波束會分為反射和透射兩部分。反射和透射的能量比可通過缺陷大小任意調(diào)節(jié)。直角轉(zhuǎn)彎機制和分波機制突破了自準直聲信號只能沿直線傳播的限制,將其推廣為未來多功能復合聲學器件中信號傳輸?shù)囊环N有效手段,對于聲學器件的集成化發(fā)展有一定的推動作用。最后,通過改變晶體中某一格點或某一排格點的幾何參數(shù)可以構(gòu)建點缺陷和線缺陷。利用有限元法與超胞法能夠十分方便地計算出表面聲子晶體的點缺陷和線缺陷對應的缺陷態(tài)帶結(jié)構(gòu),以及特定頻率的聲波局域在點缺陷與線缺陷的本征壓力場圖�；谌毕輵B(tài)的分析,我們實現(xiàn)了表面結(jié)構(gòu)聲波導。此外,研究的自準直聲束在不同平面的轉(zhuǎn)彎則是將結(jié)構(gòu)聲表面波從二維結(jié)構(gòu)表面拓展到三維空間傳輸。
[Abstract]:The rich physical connotation of phonon crystals has aroused the interest of the research, and its rich and adjustable dispersion relationship makes acoustic waves have a variety of unique modes of propagation in phononic crystals. In this paper, the manipulation of structural surface acoustic waves in surface phonon crystals is studied. We know that structural surface acoustic waves, as a new type of surface waves, have attracted extensive attention in recent years, and they not only have the characteristics of surface waves. At the same time, it has its own advantages, many of the physical phenomena of surface waves can be studied through the measurement and analysis of structural surface acoustic waves. In this paper, the study of structural surface acoustic wave has a certain guiding significance for the design of multifunctional integrated acoustic devices. The main work of this paper is as follows: firstly, the influence of geometric parameters on the dispersion of structural saw is studied. It is found that the wider and deeper grooves on rigid plates can obtain better localized structural surface acoustic waves. We design a three-dimensional rigid plate with periodic grooves, and obtain a very flat surface acoustic wave isofrequency dispersion line, and realize the self-collimation transmission of the structure surface acoustic wave by using the unique shape of the equal frequency dispersion line. This will provide some theoretical guidance for the design of new acoustic devices. Secondly, a 45 擄wedge-shaped surface phonon crystal can be used to realize the right-angle turn and imaging of the structural surface acoustic wave. The half-maximum width of the imaging is 0.316 位. If two wedge-shaped phonon crystals are combined and a line defect is introduced, the incident collimation beam will be divided into two parts: reflection and transmission. The energy ratio of reflection and transmission can be adjusted arbitrarily by defect size. The right-angle turning mechanism and the split-wave mechanism have broken through the restriction that the autocollimator acoustic signal can only propagate along the straight line, and it has been extended to be an effective means of signal transmission in the future multifunctional composite acoustic devices. It can promote the integrated development of acoustic devices. Finally, point defects and line defects can be constructed by changing the geometric parameters of a lattice or a row of lattice points in a crystal. The finite element method and the supercell method can be used to calculate the defect band structure of the point defect and the line defect of the surface phonon crystal and the intrinsic pressure field diagram of the acoustic wave localized at the point and line defect of the specific frequency. Based on the analysis of defect states, a surface structure acoustic waveguide is realized. In addition, the turning of the self-collimating sound beam in different plane is to extend the surface acoustic wave from the two-dimensional surface to the three-dimensional space.
【學位授予單位】：吉首大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O735

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本文編號：2157041