摘要
为提高电磁超声检测信号的信噪比,研究激励信号频率、脉宽及换能器提离距离对厚度测量结果的影响,搭建了电磁超声实验系统。该系统利用RITEC-SNAP 5000产生高能正弦波激励电磁超声换能器EMAT(Electromagnetic Acoustic Transducer),通过调节激励信号的频率、脉宽,改变提离距离来观测超声回波幅度的变化。实验结果表明:当激励频率和EMAT固有频率相同时其换能效率最高,采用6个周期的脉冲串时前后波包之间分界明显,为获得较大的回波幅度应尽可能减小提离距离。
In order to improve the SNR of the thickness measurement testing,study the effects caused by the excitation signal and transducer lift-off distance,setting the electromagnetic ultrasonic experiment system. Using the system RITEC-SNAP 5000 produced high-energy sine wave to excite the electromagnetic ultrasonic transducer（ EMAT）,by adjusting the frequency of the excitation signal,pulse width,change the lift-off distance to observe the change of the ultrasonic echo amplitude. The experiment results showed that,when the excitation frequency was equal to the inherent frequency of EMAT,the transducer high worked efficiency; using six cycles of pulse sequence,the wave boundary between before and after was apparent; in order to obtain larger echo amplitude,the lift-off distance should be minimized.
出处
《传感技术学报》
CAS
CSCD
北大核心
2015年第4期498-502,共5页
Chinese Journal of Sensors and Actuators
基金
国家自然科学基金项目(61201412)
关键词
电磁超声
无损检测
厚度测量
激励频率
提离距离
electromagnetic ultrasonic
nondestructive testing
thickness measurement
excited frequency
lift-off distance
