摘要
将Barker码脉冲压缩技术应用于水平剪切(SH)导波电磁超声换能器(EMAT),对提高在役钢板腐蚀检测回波的信噪比(SNR)和空间分辨率,以及实现大范围在线快速扫查具有重要的工程应用价值。建立基于Barker码信号激励的钢板SH导波传播有限元模型,结合实验分析与数值计算,分析了Barker码序列长度、码元长度、EMAT设计参数、提离等因素对脉冲压缩后缺陷回波的信噪比和波包宽度的影响,并与传统单一频率脉冲串激励方式进行对比实验。结果表明:与单一频率脉冲串激励方式相比,采用Barker码脉冲压缩技术,可以将缺陷波的SNR提高5.8 dB;当EMAT提离为3.0 mm时,经过脉冲压缩后的缺陷回波SNR>8.7 dB,而采用单一频率脉冲串激励方式对应的SNR接近于0 dB;当Barker码信号序列长度为13位、码元长度为15μs时,能检测深度为1 mm、直径为20 mm的圆孔,且SNR>25.4 dB。
The application of Barker code pulse compression technique in a shear horizontal(SH)guided wave electromagnetic acoustic transducer(EMAT)has significant value in engineering application as it enhances the signal-to-noise ratio(SNR)and spatial resolution of the corrosion echo detected in in-service steel plates,and helps to realize large-scale and rapid on-line scanning.In this paper,a finite element model of SH-guided wave propagation in a steel plate excited by Barker code signals is established.Then,combined with experimental analysis and numerical calculations,the effects of Barker code sequence length,subpulse length,EMAT design parameters,and lift-off on the SNR and wave packet width of the pulse-compressed echoes are analyzed and compared with those of the traditional tone-burst excitation method.The results show that the SNR of the defect echo processed with the Barker code pulse compression technique is 5.8 dB higher than that with the tone-burst excitation method.When the EMAT liftoff is 3.0 mm,the SNR of the defect echo after Barker code pulse compression is greater than 8.7 dB,while that with the tone-burst excitation method is approximately 0 dB.When the sequence length and subpulse of the Barker code signals are respectively 13 and 15μs,a circular hole with a depth of 1 mm and a diameter of 20 mm can be detected,the SNR of which is greater than 25.4 dB.
作者
石文泽
黄祺凯
卢超
邱发生
陈尧
陈果
SHI Wenze;HUANG Qikai;LU Chao;QIU Fasheng;CHEN Yao;CHEN Guo(Key Laboratory of Nondestructive Testing of Ministry of Education,Nanchang Hangkong University,Nanchang 330063,China;State Key Laboratory of Acoustics,Institute of Acoustics,Chinese Academy of Sciences,Beijing 100190,China;Key Laboratory of Simulation and Numerical Modeling Technology of Jiangxi Province,Gannan Normal University,Ganzhou 341000,China)
出处
《北京航空航天大学学报》
EI
CAS
CSCD
北大核心
2023年第2期324-334,共11页
Journal of Beijing University of Aeronautics and Astronautics
基金
国家自然科学基金(52065049,12064001,51705231,51705232)
江西省自然科学基金(20192ACBL20052,20181BAB216020)。
关键词
钢板
水平剪切导波
电磁超声换能器
Barker码
脉冲压缩
steel plate
shear horizontal guided wave
electromagnetic acoustic transducer
Barker code
pulse compression technique
