Monitoring method for time reversal damage to no-datum Lamb wave of engineering structure

Abstract

The invention discloses a monitoring method for time reversal damage to no-datum Lamb wave of an engineering structure. The monitoring method comprises the following steps of: distributing a group of excitation / sensing arrays on a structure to be monitored; building detection channels, and collecting Lamb wave response signals of all excitation / sensing channels; intercepting the response signals, and then conducting time reversal to obtain time reversal structure response signals; loading the time reversal structure response signals onto corresponding excitation, and collecting time reversal focusing structure response signals on the corresponding sensing; and in the time reversal focusing structure response signals of all the detection channels, extracting the occurrence time difference of focusing main wave crest and sidelobe signals, taking the occurrence time difference as a characteristic parameter, calculating to obtain the position and approximate range of the damage by adopting an ellipse positioning method, and analyzing and judging the health condition of the structure to be detected. With the method, the wave packet extension and signal aliasing caused by frequency dispersion can be eliminated, no-datum active positioning and detection to the Lamb wave can be realized, and the healthy monitoring practicalization of the structure can be benefited.

Description

technical field [0001] The invention relates to a reference-free active Lamb wave time-reversal damage monitoring method for plate structures. Background technique [0002] With the continuous improvement of structural safety and reliability requirements, the on-line monitoring and diagnosis of structural damage has attracted more and more attention. In order to prevent disasters or losses caused by structural damage, effective monitoring of structures is necessary. [0003] Lamb wave is an elastic guided wave propagating in a solid structure under free boundary conditions. Due to its slow attenuation, long propagation distance, and sensitivity to small damage in the structure, it is widely used in engineering fields such as aerospace, high-speed railways, and ships. received more and more attention. Because damage can cause Lamb wave scattering, the research on damage monitoring and evaluation technology based on Lamb wave damage scattering signal is currently a hot spot. ...

AI Technical Summary

Problems solved by technology

However, there are dispersion and multi-mode effects in Lamb wave propagation, and the weak wave packets of damaged scattered signals are easily submerged in direct waves, boundary reflections, mode transformations, and noise. The subtraction method is used to obtain the Lamb wave damage scattering signal, and factors such as changes in environmental parameters and human operation errors will also cause changes in the response signal. Using the above-mentioned difference signal method can easily introduce signal deviations caused by these external factors, resulting in Misjudgment of damage monitoring

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