Ultrasonic Guided-Wave Mode Identification in Pipe by Using Air-Coupled Transducer and Time-Frequency Analysis

A preliminary study of the behavior of ultrasonic guided wave mode in a pipe using a comb transducer for maintenance inspection of power plant facilities has been verified experimentally. Guided wave mode identification is carried out in a pipe using time-frequency analysis methods such as wavelet transform (WT) and short time Fourier transform (STFT), compared with theoretically calculated group velocity dispersion curves for longitudinal and flexural mode. The results are in good agreement with analytical predictions and show the effectiveness of using the time-frequency analysis method to identify the individual guided wave modes. And, It was found out that longitudinal mode (0, 1) is affected by mode conversion less than the other modes. Therefore, L (0, 1) is selected as a optimal mode for evaluating location of the surface defect in a pipe.

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Time Frequency Domain Analysis of the Dispersion of Guided Wave Modes

Recent Advances in Nondestructive Evaluation Techniques for Material Science and Industries ◽

10.1115/pvp2004-2807 ◽

2004 ◽

Author(s):

Youn-Ho Cho ◽

Yong-Kwon Kim ◽

Ik-Keun Park

Keyword(s):

Wavelet Transform ◽

Group Velocity ◽

Frequency Analysis ◽

Time Domain ◽

Excitation Frequency ◽

Guided Wave ◽

Time Frequency Analysis ◽

Mode Identification ◽

Time Frequency ◽

Wave Modes

One of unique characteristics of guided waves is a dispersive behavior that guided wave velocity changes with an excitation frequency and mode. In practical applications of guided wave techniques, it is very important to identify propagating modes in a time-domain waveform for determination of defect location and size. Mode identification can be done by measurement of group velocity in a time-domain waveform. Thus, it is preferred to generate a single or less dispersive mode. But, in many cases, it is difficult to distinguish a mode clearly in a time-domain waveform because of superposition of multi modes and mode conversion phenomena. Time-frequency analysis is used as efficient methods to identify modes by presenting wave energy distribution in a time-frequency. In this study, experimental guided wave mode identification is carried out in a steel plate using time-frequency analysis methods such as wavelet transform. The results are compared with theoretically calculated group velocity dispersion curves. The results are in good agreement with analytical predictions and show the effectiveness of using the wavelet transform method to identify and measure the amplitudes of individual guided wave modes.

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A Time-Frequency Research for Ultrasonic Guided Wave Generated from the Debonding Based on a Novel Time-Frequency Analysis Technique

Shock and Vibration ◽

10.1155/2017/5686984 ◽

2017 ◽

Vol 2017 ◽

pp. 1-11 ◽

Cited By ~ 7

Author(s):

Junhua Wu ◽

Zheshu Ma ◽

Yonghui Zhang

Keyword(s):

Carbon Fibre ◽

Frequency Analysis ◽

Instantaneous Frequency ◽

Fibre Composite ◽

Guided Wave ◽

Carbon Fibre Composite ◽

Time Frequency Analysis ◽

Time Frequency ◽

Ultrasonic Guided Wave ◽

Carbon Fibre Composites

Carbon fibre composites have a promising application in the future of the vehicle, because of their high strength and light weight. Debonding is a major defect of the carbon fibre composite. The time-frequency analysis is fundamental to identify the defect on ultrasonic nondestructive evaluation and testing. In order to obtain the instantaneous frequency and the peak time of modes of the ultrasonic guided wave, an algorithm based on the Smoothed Pseudo Wigner-Ville distribution and the peak-track algorithm is presented. In the algorithm, a masking step is proposed, which can guarantee that the peak-track algorithm can automatically exact the instantaneous frequency and the instantaneous amplitude of different modes on the Smoothed Pseudo Wigner-Ville distribution. An experiment for detecting the debonding for a type of carbon fibre composite is done. The presented algorithm is employed on the experimental signals. The processed result of experimental signals reveals that the defect can stimulate new modes, and there is a quantitative relationship between the defect size and the frequency of the new mode. The presented technique provides a valuable way to detect the presentence, calculate the size, and locate the position of the debonding defect.

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Ultrasonic Guided-Wave Mode Identification in Pipe by Using Air-Coupled Transducer and Time-Frequency Analysis

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.321-323.804 ◽

2006 ◽

Vol 321-323 ◽

pp. 804-807 ◽

Cited By ~ 2

Author(s):

Ik Keun Park ◽

Hyun Mook Kim ◽

Yong Kwon Kim ◽

Yong Sang Cho

Keyword(s):

Guided Waves ◽

Wave Mode ◽

Guided Wave ◽

Element Space ◽

Mode Identification ◽

Time Frequency ◽

Dispersive Curve ◽

Ultrasonic Guided Wave ◽

Essential Components ◽

2D Fft

For efficient NDE of pipes, essential components of power plant facilities, ultrasonic guided waves were generated and received applying an air-coupled transducer and comb one as non-contact technology. Mode generation and selection were predicted based on theoretical dispersive curve and the element space of a comb transducer. In addition, a receiving angle of the air-coupled transducer was determined to acquire the predicted modes by theoretical phase velocity of each mode. Theoretical dispersive curve was compared with the results of the time-frequency spectroscopes based on the wavelet transform and 2D-FFT to identify the characteristics of the received mode. The received modes show a good agreement with the predicted ones.

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