Method of time-frequency ridge line analysis and travel time extraction for Lamb wave

Abstract

The invention provides a method of time-frequency ridge line analysis and travel time extraction for Lamb wave. The method comprises the steps of: obtaining a Lamb wave excitation parameter accordingto the material and the thickness of the to-be-detected object; arranging a Lamb wave emitting transducer and a Lamb wave receiving transducer; generating an excitation signal by a pulse excitation device; amplifying and filtering a Lamb wave receiving signal, and storing waveform data; performing short-time Fourier transform on the processed signal to obtain a spectrum; obtaining a peak ridge point of the spectrum; determining ridge points on the two sides of the peak ridge point; judging whether the ridge points of all discrete sampling times of the wave packet have been acquired; if so, fitting the ridge point of each discrete sampling time point, and establishing a Lamb wave time-frequency analysis ridge line, otherwise, re- determining the ridge point; and obtaining the travel time data of the Lamb wave according to the Lamb wave time-frequency analysis ridge line. According to the method of time-frequency ridge line analysis and travel time extraction for Lamb wave, the accuracyof the travel time extraction of the Lamb wave is effectively improved, and the Lamb wave imaging effect is further improved.

Description

technical field [0001] The invention relates to the technical field of non-destructive testing, in particular to a travel time extraction method for Lamb wave time-frequency ridge analysis. Background technique [0002] Ultrasonic Lamb wave imaging is an important non-destructive testing technology. Lamb wave testing technology not only inherits the advantages of good directivity and high efficiency of traditional body wave testing technology, but also has the advantages of long detection distance and the ability to simultaneously detect the difference between the upper and lower surfaces and the interior of an object. Depth of defects and other advantages. When using Lamb wave for detection, it is necessary to obtain characteristic information such as accurate shape and distribution of defects, and Lamb wave imaging technology provides a feasible solution. Lamb wave imaging technology needs to extract projection information from Lamb waves. Travel time information is more ...

AI Technical Summary

Problems solved by technology

The former requires a large number of preliminary experiments to obtain training samples, and the calculation efficiency is low, so it is difficult to apply. The latter extracts travel time based on the peak value of the time domain waveform, which is inevitably affected by noise and other factors and introduces a large error.

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