揚(yáng)聲器振膜的諧波失真
發(fā)布時(shí)間：2018-11-27 14:41
【摘要】：諧波失真是影響揚(yáng)聲器音質(zhì)的一個(gè)重要因素,諧波失真的大小往往決定著揚(yáng)聲器品質(zhì)的高低。其中總諧波失真、2次諧波失真和3次諧波失真是設(shè)計(jì)開發(fā)高品質(zhì)揚(yáng)聲器的過程中必不可少的需要測(cè)試的物理參數(shù)。揚(yáng)聲器在低頻時(shí)由于驅(qū)動(dòng)力、支撐系統(tǒng)的非線性而導(dǎo)致的諧波失真問題已有較多的文獻(xiàn)在這方面做了研究,而關(guān)于揚(yáng)聲器在中高頻段由于揚(yáng)聲器振膜的非線性彈性振動(dòng)而導(dǎo)致的諧波失真問題,研究文獻(xiàn)仍比較缺乏。碩士期間,在閱讀文獻(xiàn)的基礎(chǔ)上,主要開展了以下工作：1.推導(dǎo)了軸對(duì)稱旋轉(zhuǎn)薄殼的線性振動(dòng)微分方程組,利用此微分方程組,結(jié)合錐形揚(yáng)聲器振膜的實(shí)際幾何、材料參數(shù)和邊界條件,采用有限差分?jǐn)?shù)值計(jì)算方法,計(jì)算了錐形揚(yáng)聲器在線性振動(dòng)情況下的共振頻率、振型函數(shù)和頻響曲線,并通過與Frankort[3]的計(jì)算結(jié)果進(jìn)行對(duì)比,對(duì)本文的計(jì)算結(jié)果進(jìn)行了驗(yàn)證。2.根據(jù)假設(shè)振型函數(shù)法的基本思想,通過用揚(yáng)聲器振膜在某一驅(qū)動(dòng)頻率力下的線性響應(yīng)振型函數(shù)對(duì)連續(xù)體進(jìn)行離散,從Hamilton變分方程出發(fā)推導(dǎo)了軸對(duì)稱旋轉(zhuǎn)薄殼的非線性振動(dòng)方程,給出了方程中系數(shù)的積分形式的計(jì)算表達(dá)式。3.采用多尺度法求解了非線性振動(dòng)方程,得到了幅頻方程和3次近似解,說明了諧波項(xiàng)與非線性系數(shù)的關(guān)系。計(jì)算了特定實(shí)例下錐形揚(yáng)聲器振膜的2次、3次諧波聲壓和基波聲壓的頻率響應(yīng)曲線。4.通過采用數(shù)值計(jì)算方法,探討了錐體的幾何、材料參數(shù)對(duì)非線性系數(shù)的影響。并進(jìn)一步通過計(jì)算錐形振膜的幾何、材料參數(shù)對(duì)振型函數(shù)的影響對(duì)計(jì)算結(jié)果進(jìn)行了驗(yàn)證。計(jì)算結(jié)果表明通過選擇合適的幾何、材料參數(shù),可以使諧波失真得到一定程度的減小。5.根據(jù)軸對(duì)稱旋轉(zhuǎn)薄殼的一般理論,探討分析了指數(shù)形振膜和拋物線形振膜的力學(xué)振動(dòng)、聲輻射和非線性特性。
[Abstract]:Harmonic distortion is an important factor that affects the sound quality of loudspeakers. The magnitude of harmonic distortion often determines the quality of loudspeakers. The total harmonic distortion, the second harmonic distortion and the third harmonic distortion are essential physical parameters to be tested in the design and development of high quality loudspeakers. The problem of harmonic distortion caused by driving force and nonlinear supporting system in loudspeakers at low frequency has been studied in many literatures. However, the harmonic distortion caused by the nonlinear elastic vibration of loudspeakers in the medium and high frequency band is still lacking. During the master period, on the basis of reading the literature, the main work carried out the following: 1. The linear vibration differential equations of axisymmetric thin rotating shells are derived. The finite difference numerical method is used to calculate the vibration characteristics of thin axisymmetric shells by using the finite difference method, combining with the actual geometry, material parameters and boundary conditions of conical loudspeakers. The resonance frequency, mode function and frequency response curve of conical loudspeaker under linear vibration are calculated and compared with that of Frankort [3]. According to the basic idea of the hypothetical mode function method, the nonlinear vibration equation of axisymmetric rotating thin shell is derived from the Hamilton variational equation by using the linear response mode function of the loudspeaker diaphragm under a certain driving frequency force. The expression of integral form of coefficient in the equation is given. The nonlinear vibration equation is solved by multi-scale method. The amplitude frequency equation and the cubic approximate solution are obtained. The relationship between the harmonic term and the nonlinear coefficient is explained. The frequency response curves of the second and third harmonic sound pressure and the fundamental wave sound pressure of conical loudspeaker are calculated. 4. The effects of cone geometry and material parameters on nonlinear coefficients are discussed by numerical method. Furthermore, the calculation results are verified by calculating the geometry of the conical diaphragm and the influence of material parameters on the mode function. The calculation results show that the harmonic distortion can be reduced to a certain extent by selecting appropriate geometry and material parameters. Based on the general theory of axisymmetric rotating thin shell, the mechanical vibration, acoustic radiation and nonlinear characteristics of exponential and parabolic diaphragm are discussed and analyzed.
【學(xué)位授予單位】：浙江師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN643
本文編號(hào)：2361151
[Abstract]:Harmonic distortion is an important factor that affects the sound quality of loudspeakers. The magnitude of harmonic distortion often determines the quality of loudspeakers. The total harmonic distortion, the second harmonic distortion and the third harmonic distortion are essential physical parameters to be tested in the design and development of high quality loudspeakers. The problem of harmonic distortion caused by driving force and nonlinear supporting system in loudspeakers at low frequency has been studied in many literatures. However, the harmonic distortion caused by the nonlinear elastic vibration of loudspeakers in the medium and high frequency band is still lacking. During the master period, on the basis of reading the literature, the main work carried out the following: 1. The linear vibration differential equations of axisymmetric thin rotating shells are derived. The finite difference numerical method is used to calculate the vibration characteristics of thin axisymmetric shells by using the finite difference method, combining with the actual geometry, material parameters and boundary conditions of conical loudspeakers. The resonance frequency, mode function and frequency response curve of conical loudspeaker under linear vibration are calculated and compared with that of Frankort [3]. According to the basic idea of the hypothetical mode function method, the nonlinear vibration equation of axisymmetric rotating thin shell is derived from the Hamilton variational equation by using the linear response mode function of the loudspeaker diaphragm under a certain driving frequency force. The expression of integral form of coefficient in the equation is given. The nonlinear vibration equation is solved by multi-scale method. The amplitude frequency equation and the cubic approximate solution are obtained. The relationship between the harmonic term and the nonlinear coefficient is explained. The frequency response curves of the second and third harmonic sound pressure and the fundamental wave sound pressure of conical loudspeaker are calculated. 4. The effects of cone geometry and material parameters on nonlinear coefficients are discussed by numerical method. Furthermore, the calculation results are verified by calculating the geometry of the conical diaphragm and the influence of material parameters on the mode function. The calculation results show that the harmonic distortion can be reduced to a certain extent by selecting appropriate geometry and material parameters. Based on the general theory of axisymmetric rotating thin shell, the mechanical vibration, acoustic radiation and nonlinear characteristics of exponential and parabolic diaphragm are discussed and analyzed.
【學(xué)位授予單位】：浙江師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN643
【參考文獻(xiàn)】
相關(guān)期刊論文 前2條
1 宗豐德,張志良;揚(yáng)聲器低頻強(qiáng)非線性振動(dòng)的周期解[J];聲學(xué)與電子工程;2003年02期
2 張志良;劉世清;李小菊;;有內(nèi)共振時(shí)的揚(yáng)聲器分諧波和混沌[J];聲學(xué)學(xué)報(bào);2012年04期
，本文編號(hào)：2361151
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