光声方法测量粘弹介质声衰减的研究

Research on Acoustic Attenuation Measurement of the Viscoelastic Materials with Opto-acoustic Method

衰减是材料的一项重要参数,测量衰减将有助于评估材料的空隙率、微观裂纹分布、颗粒尺度、材料强度及软体组织结构等。该文利用光声手段对介质的表面波衰减进行了测量研究。由激光激发表面波,换能器检测。对连续采样所获得的表面波信号进行加窗、滤波、FFT处理及相干分析,得出介质衰减与频率的关系。实验结果表明,利用光声手段及表面波方法是对固体材料衰减测量的有效手段之一。

Attenuation is an important parameter of materials. Attenuation measurement of materials would help us to evaluate the void ratio, the microscopic crack distribution, the grain dimension, the soft issue structure and the materials strength. This research uses optical and acoustic means to quantify the frequency-dependent attenuation losses of Rayleigh waves in viscoelastic materials. The high fidelity, large frequency bandwidth, steady output and noncontact nature of laser excitation makes this an ideal methodology to measure attenuation in these materials. Through the signal process of windows, filtering, FFT and coherent analysis to the Rayleigh signal, the relation between attenuation and frequency is obtained. The measurement results show that opto-acoustics method is effective to the attenuation measurement of viscoelastic materials.