A Method for Testing the Group Velocity Dispersion of Structural Guided Wave Response

Abstract

A method for testing structural guided wave response group velocity dispersion, in which a single group of PZT piezoelectric element pairs are arranged on a structural member as a signal exciter and a sensor respectively to form a guided wave signal excitation-sensing measurement channel; a design is made according to the test frequency band Group narrow-band excitation signals, and collect the structural guided wave response signals under the corresponding excitation; perform time interception on all collected structural guided wave response signals, and normalize the intercepted signals according to the maximum peak amplitude of the direct wave signal, Then perform synchronous superposition according to the excitation time reference, perform time-frequency processing on the superimposed signal, and calculate the propagation dispersion characteristics of the guided wave in the structure to be tested according to the peak distribution and propagation distance in the time-frequency processing results. The method of the invention can easily realize the test and analysis of dispersion characteristics in structures such as plates, shells, pipes, columns, etc. based on the existing test conditions, and has good support and application value for the research and application of guided wave structure health monitoring.

Description

Technical field [0001] The present invention belongs to the field of guided wave monitoring technology, relates to a single group piezoelectric excitation / sensing element of the structure of the guided wave response group velocity dispersion test method, for the actual engineering structure of the guided wave signal multimodal group speed - frequency dispersion curve test, so as to achieve the engineering structure to be measured guided wave dispersion characteristic analysis and monitoring. Background [0002] With the continuous development of guided wave monitoring technology, its application is becoming more and more extensive, but due to the multi-mode and frequency dispersion characteristics of guided wave signals, there are problems of signal analysis and processing difficulties in the application process. Most of the existing research for uniform plate, shell, column structure, by solving the frequency dispersion equation to obtain the frequency dissipation curve of suc...

AI Technical Summary

Problems solved by technology

Since the piezoelectric ceramic sheet is usually pasted directly on the surface of the structure to be tested, in the process of excitation and sensing of the guided wave signal, according to the dynamic equation, the guided wave signal is excited by the shear stress transmission applied by the piezoelectric ceramic on the surface of the structure. However, when the size of the piezoelectric ceramic sheet is fixed, in this excitation process, the excited signal amplitude has frequency modulation characteristics, that is, the excited signal amplitude of each mode changes with the signal frequency; secondly , the central operating frequency of piezoelectric ceramics is generally around hundreds of kHz. In this range, the signal excitation efficiency is high, and the amplitude of the induced guided wave signal is large. However, as the frequency deviates from this central operating frequency, the excited guided wave signal Wave signal amplitude decays rapidly

Therefore, the traditional broadband pulse-type structural guided wave signal dispersion characteristic test method is difficult to apply to the structural guided wave signal dispersion measurement under the piezoelectric ceramic exciter / sensor combination, which in turn affects the mode, center frequency, and signal in the monitoring process. The selection of parameters such as form, which adds new difficulties to the application of guided wave monitoring technology

At present, for actual engineering structures, there is still a lack of fast and effective methods for testing the dispersion of guided wave response signals of structures using a single set of piezoelectric excitation / sensing element pairs.

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