材料非线性衰减系数的二次谐波测量方法研究

发布时间：2018-05-12 22:04

本文选题：二次谐波 + 衰减系数　；参考：《声学学报》2017年02期

【摘要】：采用有限幅值法测量材料在基波和非线性引起的二次谐波作用下的衰减系数:利用准线性下的KZK方程推导基波和二次谐波的声压分布,并提取波束修正系数;采用短纯音信号进行非线性实验,对检测得到的基波和二次谐波声压进行衍射修正处理,有效抑制衍射对衰减系数测量的不利影响,继而通过线性拟合的方法计算得到更精确的基波和二次谐波的衰减系数。以水为例进行实验,研究了实验测量所得衰减系数的频率依赖关系,结果表明在非线性条件下水的衰减系数与频率间存在较强的线性关系,而线性条件下衰减系数随频率呈现二次方增长的特性则不适用于非线性条件。该研究提出了准确测量非线性声波衰减系数的方法,为更有效地应用非线性超声检测提供理论依据。
[Abstract]:Finite amplitude method is used to measure the attenuation coefficient of material under the action of fundamental wave and nonlinear second harmonic. The sound pressure distribution of fundamental wave and second harmonic is deduced by using KZK equation under quasilinear condition, and the correction coefficient of beam is extracted. In order to suppress the negative effect of diffraction on the measurement of attenuation coefficient, the measured fundamental and second harmonic sound pressure is modified by nonlinear experiments with short tone signal. Then more accurate attenuation coefficients of fundamental and second harmonic waves are obtained by linear fitting method. Taking water as an example, the frequency dependence of the attenuation coefficient is studied. The results show that there is a strong linear relationship between the attenuation coefficient and the frequency of water under nonlinear conditions. But the characteristic that the attenuation coefficient increases with the frequency is not suitable for the nonlinear condition. In this study, an accurate method for measuring the attenuation coefficient of nonlinear acoustic waves is proposed, which provides a theoretical basis for the more effective application of nonlinear ultrasonic detection.
【作者单位】：中南大学交通运输工程学院;中国计量大学计量测试工程学院;
【基金】：国家自然科学基金项目(61271356,51575541) 中南大学硕士生自主探索创新项目(2016zzts330) 浙江省自然科学基金项目(LY15E050012)资助
【分类号】：O426.2

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