声表面波渡越时间法检测黏弹性介质表面凹痕深度的研究  

Study on depth detection of surface notches using time-of-flight method with surface acoustic waves in viscoelastic media

作　　者：孙宏祥[1,2] 许伯强[2] 张淑仪[1] 

机构地区：[1]南京大学声学研究所近代声学实验室,南京210093 [2]江苏大学理学院,镇江212013

出　　处：《声学学报》2011年第2期139-144,共6页Acta Acustica

基　　金：国家自然科学基金资助项目(11074125);江苏省高校自然科学重大基础研究资助项目(10KJA140006)

摘　　要：研究声表面波渡越时间法检测黏弹性介质表面凹痕的深度。基于频域动力学平衡方程,采用有限元方法分别在有表面凹痕的弹性和黏弹性介质中,建立激光激发声表面波的数值模型。研究材料的黏性引起的声表面波波速和频散的变化,对表面凹痕检测的影响,在此基础上,根据反射和透射声表面波的传播路径及到达时间,利用渡越时间法检测黏弹性介质中的表面凹痕。结果表明:黏性引起的声表面波频散对表面凹痕检测的影响极小,采用渡越时间法检测得到的表面凹痕的位置及深度,与数值模型的设置值符合很好,从而为黏弹性介质表面凹痕的检测提供有效的理论方法。Depth detection of surface notches using a time-of-flight method with surface acoustic waves in viscoelastic media is investigated.Based on the dynamic equilibrium equations in the frequency domain,the numerical models are established to simulate the laser-generated surface acoustic waves in the elastic and viscoelastic media with the surface notches by a finite element method.The influences of the variations of the velocity and dispersion of the surface acoustic waves,which are caused by the viscous property of the material,on the detection of the surface notches are studied. Besides,according to the propagation paths and arrival times of the reflected and transmitted surface acoustic waves,the surface notches in the viscoelastic media are detected by the time-of-flight method.The results show that the dispersion of the surface acoustic waves has little impact on the detection of the surface notches.The position and depth of the surface notches,which are detected by the time-of-flight method,agree well with the values used in the numerical models. It indicates that the effective theoretical method can be obtained for surface notches detections in viscoelastic media.

关 键 词：黏弹性介质 介质表面 声表面波 时间法 凹痕 检测 渡越 数值模型 

分 类 号：O429[理学—声学]