高电导率非铁磁材料缺陷的磁声电检测新方法

Tranditional non-destructive testing methods have their own limitations. It is of great signification to explore new non-destructive testing methods, and it is also a hot research topic at present. In our previous research on low conductivity magneto-acousto electrical tomography of biological tissues, we found that magneto-acousto-electrical effects can also be used in nondestructive testing of solid nonferromagnetic materials with high conductivity. This method has high spatial resolution of ultrasonic testing and can also overcome the skin effect of eddy current testing. Therefore, this project intends to study the mechanism and method of nondestructive testing based on magneto-acousto-electrical effects. A mathematical and physical model of magneto-acousto-electrical effect and a numerical simulation model of multiple physical fields in the presence of defects in materials will be build. On this basis, the law of response about electromagnetic signals to various defects is further revealed. Because the detected electromagnetic signal is a noise-containing weak signal, it is proposed to use the modern signal processing technology as a tool to search for a method of de-noising and feature extraction suitable for the weak defect electromagnetic signal. Aiming at the problem that the detection resolution is affected by the aliasing of the detection signal due to the near surface defect or the small defect, a suitable method of aliasing signal separation will be studied in this project. The successful development of the project will expand the theory of eddy current testing, enrich the methods of nondestructive testing, and provide new ideas and methods for nondestructive testing of material defects.

传统的无损检测方法存在各自的局限性，探寻新的无损检测方法具有重要的意义，也是目前的热点研究课题。我们前期对生物组织低电导率磁声电成像研究时发现磁声电效应也能用于高电导率固体非铁磁材料的无损检测，该方法具备超声检测的高空间分辨率，同时又能克服涡流检测的趋肤效应。因此，本项目拟研究磁声电缺陷无损检测机理及方法；建立在缺陷存在情况下磁声电效应的数学物理模型及多物理场数值仿真模型；在此基础上，进一步揭示电磁信号对各种不同缺陷的响应规律。由于所检测的电磁信号为含噪微弱信号，拟以现代信号处理技术为工具，探寻适合微弱缺陷电磁信号的去噪及其特征提取方法。针对近表面缺陷或者缺陷较小时容易产生检测信号混叠而影响检测分辨力问题，研究合适本项目的混叠信号分离方法。项目的顺利开展将扩充现有的涡流检测理论，丰富无损检测方法，为材料缺陷无损检测提供新思路、新方法。

传统的无损检测方法存在各自的局限性，探寻新的无损检测方法具有重要意义，也是目前的热点研究课题。项目组利用磁声电效应对高电导率固体非铁磁材料的无损检测方法进行了研究，证实了该方法具备超声检测的高空间分辨率，同时又能克服涡流检测的趋肤效应。本项目研究了磁声电缺陷无损检测的机理及方法；建立了高电导率非铁磁材料情况下磁声电缺陷检测的数学物理模型及多物理场数值仿真模型；在此基础上，开展了大量的仿真实验，设计并优化了实验平台，制作了各种尺寸的缺陷试块，开展了相关实验，获得了实验信号，揭示了电磁信号对各种不同缺陷的响应规律。由于所检测的电磁信号为含噪微弱信号，研究了小波分析、EMD及现代滤波方法，提出了适合微弱缺陷电磁信号的去噪方法。项目研究的顺利开展获得了缺陷数据，证实了该方法能用于高电导率非铁磁材料缺陷检测，课题的研究成果将扩充现有的无损检测理论，丰富无损检测方法，为材料缺陷无损检测提供新思路、新方法。