發(fā)布時間：2018-07-03 10:07

  本文選題：徑向振動壓電換能器 + 等效電路　； 參考：《浙江師范大學(xué)》2014年碩士論文

【摘要】：功率超聲換能器是電能與聲能(或機械能)互為轉(zhuǎn)換的一種超聲設(shè)備。在功率超聲技術(shù)領(lǐng)域應(yīng)用較廣的是夾心式縱向振動壓電超聲換能器,這類換能器的設(shè)計理論基本完善。為滿足應(yīng)用的需求,發(fā)展起來一類大功率徑向復(fù)合壓電換能器,由于該類徑向復(fù)合超聲換能器的功率密度大、聲輻射效率高、徑向聲輻射指向性均勻,因此在液體超聲處理領(lǐng)域中的應(yīng)用前景十分廣闊,并逐漸成為該領(lǐng)域的研究熱點。 目前有不少學(xué)者對兩元或者三元徑向復(fù)合壓電換能器的徑向振動、縱徑耦合振動模式進行了一定研究,但這類換能器基本采用熱脹冷縮法進行裝配,需要較高的加工工藝,且預(yù)應(yīng)力大小、均勻性不容易控制,熱穩(wěn)定性仍需提高。 本文針對上述大功率換能器應(yīng)用中存在的問題,對三元徑向復(fù)合壓電換能器進行了改進和初步研究。徑向復(fù)合換能器主要由三部分組成：內(nèi)外層均為金屬預(yù)應(yīng)力管,中間層為壓電陶瓷晶片。不同的是,本文中單層結(jié)構(gòu)的徑向復(fù)合換能器中的壓電單元采用的是壓電薄圓片環(huán)形排列而成。根據(jù)夾心式縱向振動壓電換能器的理論設(shè)計,本文對這類三元徑向振動壓電換能器還做了進一步改進,提出了層疊式三元徑向復(fù)合壓電換能器。為了使復(fù)雜的裝配工藝簡單化以及解決預(yù)應(yīng)力均勻性等問題,本文將內(nèi)部金屬預(yù)應(yīng)力管替換為一種柱形彈性膨脹內(nèi)芯,該內(nèi)芯不需要高精度的熱加工,可隨意拆卸。本文通過理論、有限元法以及實驗對單層和雙層壓電陶瓷三元徑向復(fù)合超聲換能器的徑向振動特性分別進行了分析,實驗測試值與理論結(jié)果基本一致。具體進行了如下的工作： 1.分別對各向同性的金屬薄圓盤、薄圓環(huán)以及薄壁短管徑向振動特性進行了簡要的研究。由機電類比原理,得到了各組分的等效電路、共振頻率方程。 2.對單層壓電陶瓷三元徑向復(fù)合壓電超聲換能器的徑向振動特性進行了研究,導(dǎo)出了分割處理的壓電陶瓷管準(zhǔn)厚度模振動機電等效電路,通過連續(xù)邊界條件,進而得到了換能器的徑向振動等效電路及頻率方程。探討了換能器的性能參數(shù)與其管壁厚度、壓電陶瓷位置之間的關(guān)系。 3.根據(jù)夾心式縱向振動壓電換能器的設(shè)計方法,在單層結(jié)構(gòu)基礎(chǔ)上,提出了復(fù)合層(一般為偶數(shù)層)夾心式徑向振動壓電超聲換能器。由網(wǎng)絡(luò)級聯(lián)理論得到了復(fù)合層壓電陶瓷晶的準(zhǔn)厚度振動機電等效電路模型,從而建立了夾心式徑向振動壓電換能器的機電類比電路,得出了其共振、反共振頻率方程。分析了該換能器第一、二階徑向共振頻率、有效機電耦合系數(shù)與其幾何尺寸之間的依賴關(guān)系。 4.利用ANSYS有限元仿真軟件,對夾心式徑向復(fù)合壓電換能器的徑向振動進行了模態(tài)分析。在理論和有限元分析的基礎(chǔ)上,分別制作加工了幾個管壁厚度不同的單層及雙層壓電陶瓷徑向復(fù)合換能器樣品,對其共振頻率進行了實驗測試。結(jié)果表明,理論計算與有限元仿真結(jié)果以及實驗測試結(jié)果基本符合。
[Abstract]:The power ultrasonic transducer is a kind of ultrasonic equipment which converts between the electric energy and the sound energy (or the mechanical energy). It is widely used in the field of power ultrasonic technology, the sandwich type longitudinal vibration piezoelectric ultrasonic transducer, the design theory of this type of transducer is basically perfect. In order to meet the demand of the application, a kind of high-power radial composite piezoelectric transducer is developed. Because of the high power density, high efficiency of sound radiation and uniform directivity of radial sound radiation, the radial composite ultrasonic transducer is widely used in the field of liquid ultrasonic treatment, and has gradually become a hot topic in this field.
At present, a lot of scholars have studied the radial vibration and longitudinal coupling vibration mode of the dual or three element radial composite piezoelectric transducer. However, this type of transducer basically adopts the heat expansion and contraction method to assemble. It needs higher processing technology, and the size of prestress is not easy to control, and the thermal stability needs to be improved.
In this paper, in view of the problems existing in the application of the high power transducer, the three element radial composite piezoelectric transducer is improved and preliminarily studied. The radial composite transducer consists mainly of three parts: the inner and outer layers are all metal prestressing tubes and the middle layers are piezoelectric ceramic wafers. According to the theoretical design of the sandwich longitudinal vibration piezoelectric transducer, this kind of three element radial vibration piezoelectric transducer is further improved, and a laminated three element radial composite piezoelectric transducer is proposed in this paper, which makes the complex assembly process simple and solved. In this paper, the internal metal prestressed tube is replaced by a cylindrical elastic expansion inner core, which does not need high precision hot working and can be dismantled at will. The radial vibration characteristics of the three element radial composite ultrasonic transducer are carried out by the theory, the finite element method and the experiment. The experimental results are basically consistent with the theoretical results.
1. the radial vibration characteristics of isotropic thin metal disk, thin circular ring and thin wall tube are briefly studied. The equivalent circuit and resonance frequency equation of each component are obtained by the principle of mechanical and electrical analogy.
2. the radial vibration characteristics of the single layer piezoelectric ceramic three element radial composite piezoelectric ultrasonic transducer are studied. The electromechanical equivalent circuit of the quasi thickness mode vibration of the piezoelectric ceramic tube is derived. The equivalent circuit and frequency equation of the radial vibration of the transducer are obtained through the continuous boundary conditions. The relationship between the number and the thickness of the tube wall and the position of the piezoelectric ceramic.
3. based on the design method of the sandwich longitudinal vibration piezoelectric transducer, a composite layer (usually even layer) sandwich radial vibration piezoelectric ultrasonic transducer is proposed on the basis of a single layer structure. The quasi thickness vibration electromechanical equivalent circuit model of the composite laminating piezoelectric Tao Cijing is obtained by the network cascade theory, and the radial vibration of the sandwich type is established. The electromechanical analog circuit of the piezoelectric transducer has obtained its resonance and the inverse resonance frequency equation. The dependence of the first, second order radial resonance frequency on the transducer, the effective electromechanical coupling coefficient and its geometric size is analyzed.
4. using the ANSYS finite element simulation software, the radial vibration of the sandwich radial composite piezoelectric transducer is analyzed. On the basis of the theory and the finite element analysis, several single layer and double-layer piezoelectric ceramic radial composite transducer with different thickness of the tube wall are fabricated, and the resonance frequency is tested. The results show that the theoretical calculation is basically consistent with the finite element simulation and experimental results.
【學(xué)位授予單位】：浙江師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TB552

【參考文獻】

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1 胡文容,錢夢，

本文編號：2093284