基于激光激发多模态超声波速测量的材料弹性常数测定  

Determination of Elastic Constants of Materials Based on the Velocity Measurement of Laser-Generated Multi-mode Ultrasound

作　　者：董利明[1] 倪辰荫[1] 沈中华[1] 倪晓武[1] 

机构地区：[1]南京理工大学理学院,江苏南京210094

出　　处：《中国激光》2011年第4期203-207,共5页Chinese Journal of Lasers

基　　金：国家自然科学基金(60778006和60878023)资助课题

摘　　要：提出了利用精确测量激光激发的多种模态的超声波速来测定各向同性材料密度和二阶弹性(SOE)常数的实验系统和方法。把Nd:YAG激光器产生的激光聚焦成线源在样品表面不同位置激发3种模态的超声波,采用自行设计的压电陶瓷(PZT)传感器分别探测接收表面波、纵波和横波信号。利用扫描激光源技术和波形相关技术精确测算表面波波速,再根据体波传播距离和到达时间分别计算纵波和横波波速,最后根据瑞利方程和克里斯托费尔的弹性理论,计算得到材料的密度和二阶弹性参数。实验结果表明,该方法测得的铝样品的密度和二阶弹性常数C11,C44具有较高的可靠性和测量精度。A new method based on the measurement of velocity of laser-generated ultrasound is proposed to determinate the second order elastic（SOE） constants and density of isotropic materials.A serial of ultrasonic pulses can be detected by self-made PZT transducer fixed in the detection point when scanning the line source focused from Nd：YAG laser with electronic control translation stage.Then the velocity of Rayleigh waves is computed by waveform cross-correlation technique;the velocities of longitudinal wave and shear wave reflected by the bottom surface of the sample are obtained by different traveling time with their propagation distance.At the end,the SOE constants and density of isotropic material are determinated according to the Christoffel theory of elasticity.Results show that the values of SOE constants and density which signed with C11,C44 and ρ agree well with the corresponding parameters reported in the existing papers.What′s more,the relative accuracy of the determinated parameters indicated from error analysis demonstrates the feasibility and reliability of this method.

关 键 词：激光超声 二阶弹性常数 多模态超声 波速 

分 类 号：TN247[电子电信—物理电子学]