| Structural health monitoring as a technique for damage identification of in-service engineering structures,is widely used in multiple industries and fields.In structural health monitoring of large-scale component monitoring capability,network monitoring mode and the wireless monitoring means,under the urgent need of detecting in order to solve a wide range of monitoring system,refinement,and the problem of big data wireless transmission,breakthrough the limitations of structural health monitoring technology present situation,this article put forward the monitoring scheme based on multi-channel ultrasonic guided wave.On the one hand,ultrasonic guided wave as a nondestructive testing technology has a wide detection range with strong detection capability and many other advantages,but there are still large component characteristics of low positioning accuracy,such as the special structure of the energy attenuation serious insufficiency,the ultrasonic guided wave phased array,multi-channel technology,can lead to real-time focusing technique for detecting a greater range of at the same time,the implementation of fine detection,increase the feature location accuracy and guided wave signal SNR;On the other hand,the large-scale,networked and wireless monitoring background,as well as the introduction of multiple channels,have brought great challenges to the cost,storage and transmission,battery life of the monitoring sensor network and the real-time performance of the monitoring system.Therefore,this paper also proposes a guided wave data compression and reconstruction scheme based on compressed sensing.Therefore,on the basis of the research and development of the multi-channel ultrasonic guided wave instrument system,the multi-channel ultrasonic guided wave real-time focusing technology and the guided wave data compression and reconstruction scheme were implemented for the representative plate and tube components to demonstrate the effectiveness and feasibility of the scheme.Specific research contents include:Chapter 1,The extensive application and trend of structural health detection are introduced in this thesis.Also the technical advantage of multi-channel ultrasonic guided wave and the urgent demand of data compression of guided wave monitoring,are put forward,and the direction for the following research is pointed out.The development of multichannel ultrasonic guided wave technology and guided wave data compression technology in the domestic and abroad is reviewed.Chapter 2,the thesis introduces the multi-channel ultrasonic guided wave technology compared with single channel differences of ultrasonic guided wave technology and advantages,and on this basis,the research and development of multi-channel ultrasonic guided wave instrument,and the relative delay between different channel accuracy and consistency of sound field energy study,for later multi-channel real-time ultrasonic focusing technology to lay the foundation.Chapter 3,the theoretical research of real-time focusing technology is carried out for plate members and tube members,and a focusing experimental platform is built to verify the local energy gain of different members by focusing technology,as well as the improvement of defect detection accuracy and positioning ability.Chapter 4,the traditional data compression methods are summarized,the advantages and feasibility of data compression based on compressed sensing are analyzed,and the theoretical research on compressed sensing is carried out,laying a foundation for the subsequent proposal of guided wave data compression and reconstruction scheme.Chapter 5,a scheme of guided wave data compression and reconstruction based on compressed sensing is proposed,which is respectively introduced from three aspects of data compression,waveform dictionary construction and reconstruction algorithm of embedded system,and the feasibility is demonstrated by experiments.Chapter 6,the research content and results of this thesis are summarized,and the future research direction is put forward. |
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