Q值测量的等效声阻抗法

回顾了实验室中超声波测量Ｑ值的四种常用方法：上升时间法、回声法、频谱振比法和波形反演法。在综合了回声法和频谱振幅比法优点的基础上，提出等效声阻抗法。该方法借助于参考样品，利用其一、二次波的振幅谱，计算换能器和耦合层的等效声阻抗，进而由等测样品的一、二次波振幅普计算其衰减，求得其与频率有关的Ｑ值。对振幅谱进行了扩散校正，并利用方法一了有机玻璃和饱水岩石样品的Ｑ值。对该方法的可靠性也进行了讨论。

Equivalent Acoustic Impedance Technique for Measuring Q Value

The four common ultrasonic methods for measuring Q value in the laboratory, rise time, pulse echo, spectral ration and waveform inversion techniques are reviewed. Based on synthesizing advantages of the pulse echo and spectral ration techniques, a new method, the equivalent acoustic impedance technique is proposed. Using spectra of the first and second waves in reference, the equivalent acoustic impedance of the transducer and couplet is calculated; attenuation of the sample is estimated by analyzing the spectra of the first and second waves in it, and the Q value spectrum for the sample is obtained from the attenuation finally. Diffraction for the spectra is corrected and the Q values of organic glass and water-saturated rock samples are measured. The reliability of this method is also discussed.