电磁超声在钢管探伤中的应用  

Application of electromagnetic acoustic in steel pipe inspection

作　　者：高松巍[1] 李冰[1] 邢燕好[1] 

机构地区：[1]沈阳工业大学信息科学与工程学院,沈阳110870

出　　处：《沈阳工业大学学报》2009年第5期582-586,600,共6页Journal of Shenyang University of Technology

基　　金：国家科技部支撑计划项目(2006BAJ16B03-02)

摘　　要：为了提高超声波换能器的电-声转换效率与探伤精度,利用直接频率合成技术对电磁超声表面波进行激励,并采用选频放大技术对电磁超声接收信号进行处理.实验分析中通过改变激励信号的强度、频率、脉冲串个数、激发相位,得到电磁超声波激发的最佳条件,所设计的锁相放大电路能将微弱的电磁超声接收信号从强噪声背景中分离,有效改善接收信号的信噪比.实验结果表明,电磁超声检测方法可以实现无接触测量,适用于高温、高速、涂覆状态下的超声检测.In order to increase the electric acoustic transformation efficiency of ultrasonic transducer and inspection precision, the direct digital synthesis （DDS） technology was used for the excitation of electromagnetic acoustic surface wave, and a frequency-selecting amplification technique was applied in the treatment of electromagnetic acoustic receiving signals. The optimal condition for the electromagnetic acoustic excitation was obtained by changing the excitation signal intensity, frequency, pulse number and excitation phase in the experimental analysis. The designed lock-in amplifier can separate the weak electromagnetic acoustic receiving signal from a strong noise background and effectively improve the signal to noise ratio of the received signal. The experimental results show that the present electromagnetic acoustic inspection method can realize non-contact measurement and is suitable for the ultrasonic inspection under the high temperature, high speed and coated states.

关 键 词：电磁超声 换能器 激励电流 表面波 锁相放大 直接数字合成 前置放大 积分电路 

分 类 号：TN784.1[电子电信—电路与系统]