Structural guided wave response group velocity frequency dispersion test method

Abstract

The invention relates to a structural guided wave response group velocity frequency dispersion test method. A single PZT piezoelectric element pair is arranged on a structural part, and PZT piezoelectric elements respectively serve as a signal exciter and a sensor, thus a guided wave signal excitation-sensing measurement channel is formed; according to a test frequency band, designing a group of narrow-band excitation signals, and acquiring structural guided wave response signals under corresponding excitation; performing time interception on all the acquired structural guided wave response signals and respectively performing normalizing processing on the intercepted signals according to maximum peak amplitudes of direct wave signals, then performing synchronous overlap according to an excitation moment benchmark, performing time-frequency processing on an overlapped signal, and calculating according to wave crest distribution in a time-frequency processing result as well as a propagation distance to obtain guided wave propagation frequency dispersion characteristic in a to-be-detected structure. The test method provided by the invention can be based on existing test conditions, simply realizes test and analysis on frequency dispersion characteristic in structures such as a plate, a shell, a pipe and a column and has better supporting effect and application value on health monitoring study and application of a guided wave structure.

Description

technical field [0001] The invention belongs to the technical field of guided wave monitoring, and relates to a method for testing the group velocity dispersion of the guided wave response of a structure using a single set of piezoelectric excitation / sensing elements, which is used for multimodal group velocity-frequency of guided wave signals in actual engineering structures Dispersion curve test, so as to realize the analysis and monitoring of the guided wave dispersion characteristics of the project structure to be tested. Background technique [0002] With the continuous development of guided wave monitoring technology, its application is becoming more and more extensive. However, due to the multi-mode and dispersion characteristics of guided wave signals, there are problems in signal analysis and processing in the application process. Most of the existing research focuses on uniform plates, shells, and cylinders, and obtains the dispersion curves of such structures to b...

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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