Barker码脉冲压缩技术在铝合金电磁超声表面波检测的应用研究  

Application of Barker-Coded Pulse Compression Technique in Aluminum Alloy detection with Surface Wave EMATs

作　　者：程豆 石文泽[1] 卢超[1,2] 陈果 陈尧[1] 曾光登[3] CHENG Dou;SHI Wenze;LU Chao;CHEN Guo;CHEN Yao;ZENG Guangdeng(Key Laboratory of Nondestructive Testing of the Ministry of Education,Nanchang Hangkong University,Nanchang Jiangxi 330063,China;Key Laboratory of Simulation and Numerical Modeling Technology of Jiangxi Province,Gannan Normal University,Ganzhou Jiangxi 341000,China;Xi'an Aerospace Composites Research Institute,Xi'an Shaanxi 100190,China)

机构地区：[1]南昌航空大学无损检测教育部重点实验室,江西南昌330063 [2]赣南师范大学江西省数值模拟与仿真技术重点实验室,江西赣州341000 [3]西安航天复合材料研究所,陕西西安100190

出　　处：《传感技术学报》2022年第9期1230-1239,共10页Chinese Journal of Sensors and Actuators

基　　金：国家自然科学基金(52065049,51705231,12064001,51705232);江西省自然科学基金(20181BAB216020,20192ACBL20052);江西省科技厅科技计划项目(20192BCD40028)。

摘　　要：针对高温铝合金铸锻件在大提离、表面粗糙等恶劣条件下进行在线、快速检测时电磁超声检测回波信噪比差这一问题,建立了基于Barker码脉冲压缩技术的曲折线圈电磁超声换能器(Electromagnetic Acoustic Transducer, EMAT)检测过程有限元模型。采用正交试验表,分析了Barker码码元周期数、EMAT设计参数等对脉冲压缩后的主瓣峰值和主瓣宽度的影响,分别获取了主瓣峰值/主瓣宽度最佳的EMAT参数组合,并通过实验加以验证;比较了不同同步平均次数和提离距离时传统猝发音驱动方式和Barker码脉冲压缩技术对应的检测回波信噪比,并验证了Barker码脉冲压缩技术在无同步平均条件下对长5 mm×宽1 mm×深0.5 mm裂纹的检测能力。结果表明:在提离为0.3 mm时,与16次同步平均抑噪的猝发音驱动方式相比,采用Barker码脉冲压缩技术在无同步平均条件下可以将超声回波信噪比提高4.0 dB。在提离为1.3 mm和无同步平均的条件下,猝发音驱动方式难以获取足够信噪比的超声回波,而通过Barker码脉冲压缩技术则可以将超声回波的信噪比提高20.3 dB。对于长5 mm×宽1 mm×深0.5 mm裂纹,16次同步平均抑噪的猝发音驱动方式无法可靠获取缺陷波,而采用无同步平均的Barker码脉冲压缩技术,其缺陷波信噪比可达12.0 dB,较32次同步平均抑噪的猝发音驱动方式提高了2.0 dB。When high-temperature aluminum alloy castings and forgings are tested online and quickly under severe conditions such as large lift-off and rough sample surface, there will be the problem of poor signal-to-noise ratio(SNR)of electromagnetic ultrasonic echo. A finite element model for the testing process of a meander coil Electromagnetic Acoustic Transducer(EMAT)based on Barker-coded pulse compression technique is established to solve this problem. The orthogonal test table is used to analyze the influences of the number of element cycles of Barker-coded signal and EMAT design parameters on the main lobe peak and main lobe width after pulse compression. The optimal EMAT parameter combination of main lobe peak/main lobe width is obtained and verified through experiments, respectively. The SNR of detection echo corresponding to traditional tone-burst excitation method and Barker-coded pulse compression technique is compared with different synchronous average times and lift-off distances. Besides, it is verified that the Barker-coded pulse compression technique can detect the crack of 5 mm(length)×1 mm(width)×0.5 mm(depth)without synchronous average. The results show that when the lift-off is 0.3 mm, the SNR of the ultrasonic echo using Barker-coded pulse compression technique with 16 times synchronous average can be improved by 4.0 dB,compared with the SNR of the tone-burst excitation with 16 times synchronous average. Besides, when the lift-off is 1.3 mm and there is no synchronous average, it is difficult for the tone-burst excitation method to obtain the ultrasonic echo with sufficient SNR,while the Barker-coded pulse compression technique can improve the SNR of the ultrasonic echo by 20.3 dB. For the crack of 5 mm(length),1 mm(width),and 0.5 mm(depth),the tone-burst excitation method with 16 times synchronous average cannot accurately obtain the defect echo. However, by using the Barker code pulse compression technique without synchronous average, the SNR of defect echo can reach 12.0 dB,which is 2.0 dB higher

关 键 词：曲折线圈EMAT 优化设计 正交试验 脉冲压缩 高温铸锻件 

分 类 号：TB552[理学—物理] TH878[理学—声学]