薄板缺陷的兰姆波全聚焦优化成像  

Lamb wave optimized total focusing imaging for defects in thin plates

作　　者：张海燕[1] 张语心 张辉 朱文发[2] 朱琦 ZHANG Haiyan;ZHANG Yuxin;ZHANG Hui;ZHU Wenfa;ZHU Qi(School of Communication and Information Engineering,Shanghai University,Shanghai 200444,China;School of Urban Rail Transportation,Shanghai University of Engineering Science,Shanghai 201620,China;School of Mechatronic and Automation Engineering,Shanghai University,Shanghai 200444,China)

机构地区：[1]上海大学通信与信息工程学院,上海200444 [2]上海工程技术大学城市轨道交通学院,上海201620 [3]上海大学机电工程与自动化学院,上海200444

出　　处：《声学技术》2025年第1期40-47,共8页Technical Acoustics

基　　金：国家自然科学基金(12174255,12374443)资助项目。

摘　　要：全聚焦算法依靠信号的幅度信息进行延迟叠加(delay and sum,DAS)成像,实际应用中信号并非总能满足相干叠加这一前提,而非相干信号的叠加导致噪声和伪影。文章提出一种循环相干因子(circular coherence factor,CCF)加权的延迟乘和(delay multiply and sum,DMAS)CCF-DMAS优化算法,实现薄板中缺陷的兰姆波全聚焦成像。该方法考虑接收阵元间的空间相干性,对接收信号进行相乘耦合,利用数据中的相位信息计算相干因子实现自适应加权,以扩大相干和非相干信号间的差异,从而达到缩窄主瓣,减少旁瓣,提高成像分辨率的效果。建立超声阵列发射、接收实验系统,通过楔块耦合,在含通孔缺陷的锆合金薄板上激发S_(0)模态兰姆波,捕获全矩阵数据;通过CCF-DMAS算法对采集的数据相位加权,生成新的频率分量;利用带通滤波保留二次谐波分量进行全聚焦成像。实验结果表明:与DAS和DMAS全聚焦成像算法相比,CCF-DMAS全聚焦优化算法能够有效抑制噪声和伪影,信噪比提高约39%和22%,阵列性能指数提高约86%和69%,为薄板无损检测的后处理提供了一种有效的改进方案。The traditional total focusing method(TFM)mainly relies on the amplitude information of the signals for delay and sum(DAS).In practical applications,signals may not always meet the prerequisite of coherent superposition However,the superposition of incoherent signals can lead to the generation of artifacts in result images.To solve this issue,an optimized total focusing imaging method(CCF-DMAS)with delay multiply and sum(DMAS)weighted by circular coherence factor(CCF)is proposed in this paper,which could realize Lamb wave total focusing imaging of defects in thin plates.Considered with the spatial coherence between the receiving array elements,the received signals is multiplied and coupled in this method.Meanwhile,the phased weighted factor is calculated based on phase information in the data to expand the differences between coherent and incoherent signals,which can narrow the main lobe,reduce sidelobes,and improve imaging resolution.In this study,an ultrasonic array data acquisition experimental system is established to excite S_(0) mode Lamb wave on a zirconium alloy thin plate with through-hole defects and capture full matrix data.The new frequency components are generated by phase weighting the collected data using proposed CCF-DMAS.Then the second harmonic component is retained by bandpass filtering for total focusing imaging.The experimental results show that CCF-DMAS can effectively suppress noise and artifacts,with a signal-tonoise ratio improvement of about 39%and 22%,and an array performance index(API)improvement of about 86%and 69%compared to DAS and DMAS.It provides an effective improvement scheme for the post-processing of nondestructive testing on thin plate.

关 键 词：延迟乘和 循环相干因子 兰姆波 全聚焦优化成像 

分 类 号：TB559[理学—物理]