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Time-distance domain mapping method with frequency deviation correction effect

A technology of distance domain and frequency offset, which is applied in the field of Lamb wave dispersion compensation, can solve the problems of signal interpretation difficulties and frequency offset phenomenon of processing results, and achieve the effect of improving signal resolution and signal-to-noise ratio and facilitating signal interpretation

Active Publication Date: 2012-12-12
PLA UNIV OF SCI & TECH
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Problems solved by technology

Wilcox eliminates the frequency dispersion characteristic by transforming the signal from the time domain to the space domain [Reference 2]. Due to the influence of the wavenumber spectrum of the excitation signal during the uncorrected processing, the processing result has a frequency offset phenomenon [Reference 3]. Signal Interpretation Causes Difficulty

Method used

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  • Time-distance domain mapping method with frequency deviation correction effect
  • Time-distance domain mapping method with frequency deviation correction effect
  • Time-distance domain mapping method with frequency deviation correction effect

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Embodiment 1

[0042] In this embodiment, a 2024 aluminum plate is used as the structure to be tested, and the size is 1m×1.5m×1.5mm. The structural material parameters are listed in Table 1. There are 2 piezoelectric sheets P arranged in the structure 1 and P 2 , the position in the aluminum plate structure is as figure 2 shown. The following will use Lamb wave A 0 The implementation process of the dispersion compensation method of the present invention is given by taking the mode sensing signal as an example. In order to excite A in the structure 0 Mode-based Lamb wave monitoring signal, choose a three-peak sinusoidal modulation signal with a center frequency of 100kHz as the excitation waveform, such as image 3 shown. with P 1 As an incentive, P 2 As a sensor, the collected sensing signals such as Figure 4 , the propagation path of each wave packet in the sensing signal is as follows figure 2 shown. exist Figure 4 In the original sensing signal displayed, the first wave ...

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Abstract

The invention provides a time-distance domain mapping method with a frequency deviation correction effect. The method comprises the following steps: 1) gaining relation of a dispersion wave number and a non-dispersion wave number; 2) calculating original dispersion signal frequency spectrum; 3) gaining signal wave number spectrum; 4) correcting excitation signal wave number spectrum; and 5) calculating a non-dispersion distance domain signal of frequency offset correction. The method provided by the invention can compensate the dispersion effect in a Lamb wave signal, re-compress all wave packets expanded and deformed due to dispersion, and increase the signal resolution ratio and the signal-to-noise ratio. Besides, during processing, the wave number spectrum of an excitation signal is corrected to remain the signal wave number components unchanged before and after dispersion compensation and facilitate signal interpretation.

Description

technical field [0001] The invention belongs to the field of Lamb wave signal processing, in particular to a Lamb wave dispersion compensation method. Background technique [0002] Important structures such as manned aircraft, nuclear reactors and bridges are prone to various forms of damage during their service. In order to avoid disasters or losses caused by structural damage, long-term and effective monitoring of these structures must be carried out. Traditional non-destructive Detection technology can no longer meet the monitoring requirements. To this end, the researchers proposed the concept of structural health monitoring. Structural health monitoring technology is an online, dynamic and real-time monitoring technology, which has developed rapidly in recent years and plays an increasingly important role in the safety and reliability assessment of engineering structures. Lamb wave is an ultrasonic guided wave propagating in a plate structure. Because of its advantage...

Claims

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Application Information

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IPC IPC(8): G01N29/46
Inventor 石立华蔡建周颖慧付尚琛马丁李炎新
Owner PLA UNIV OF SCI & TECH
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