扬声器振膜的谐波失真
发布时间：2018-11-27 14:41
【摘要】：谐波失真是影响扬声器音质的一个重要因素,谐波失真的大小往往决定着扬声器品质的高低。其中总谐波失真、2次谐波失真和3次谐波失真是设计开发高品质扬声器的过程中必不可少的需要测试的物理参数。扬声器在低频时由于驱动力、支撑系统的非线性而导致的谐波失真问题已有较多的文献在这方面做了研究,而关于扬声器在中高频段由于扬声器振膜的非线性弹性振动而导致的谐波失真问题,研究文献仍比较缺乏。硕士期间,在阅读文献的基础上,主要开展了以下工作：1.推导了轴对称旋转薄壳的线性振动微分方程组,利用此微分方程组,结合锥形扬声器振膜的实际几何、材料参数和边界条件,采用有限差分数值计算方法,计算了锥形扬声器在线性振动情况下的共振频率、振型函数和频响曲线,并通过与Frankort[3]的计算结果进行对比,对本文的计算结果进行了验证。2.根据假设振型函数法的基本思想,通过用扬声器振膜在某一驱动频率力下的线性响应振型函数对连续体进行离散,从Hamilton变分方程出发推导了轴对称旋转薄壳的非线性振动方程,给出了方程中系数的积分形式的计算表达式。3.采用多尺度法求解了非线性振动方程,得到了幅频方程和3次近似解,说明了谐波项与非线性系数的关系。计算了特定实例下锥形扬声器振膜的2次、3次谐波声压和基波声压的频率响应曲线。4.通过采用数值计算方法,探讨了锥体的几何、材料参数对非线性系数的影响。并进一步通过计算锥形振膜的几何、材料参数对振型函数的影响对计算结果进行了验证。计算结果表明通过选择合适的几何、材料参数,可以使谐波失真得到一定程度的减小。5.根据轴对称旋转薄壳的一般理论,探讨分析了指数形振膜和抛物线形振膜的力学振动、声辐射和非线性特性。
[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.
【学位授予单位】：浙江师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN643
本文编号：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.
【学位授予单位】：浙江师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN643
【参考文献】
相关期刊论文 前2条
1 宗丰德,张志良;扬声器低频强非线性振动的周期解[J];声学与电子工程;2003年02期
2 张志良;刘世清;李小菊;;有内共振时的扬声器分谐波和混沌[J];声学学报;2012年04期
，本文编号：2361151
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