A Study on the Behavior of Ultrasonic Guided Wave Mode in a Pipe Using a Comb Transducer

2005 ◽  
Vol 297-300 ◽  
pp. 2182-2186
Author(s):  
Ik Keun Park ◽  
Yong Kwon Kim ◽  
Youn Ho Cho ◽  
Won Joon Song ◽  
Yeon Shik Ahn ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Mode Conversion ◽  
Group Velocity Dispersion ◽  
Longitudinal Mode ◽  
Wave Mode ◽  
Guided Wave ◽  
Flexural Mode ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Ultrasonic Guided Wave

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.

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

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
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.

Time Frequency Domain Analysis of the Dispersion of Guided Wave Modes

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.

A Wall Thinning Detection and Quantification Based on Guided Wave Mode Conversion Features

2006 ◽  
Vol 321-323 ◽  
pp. 795-798 ◽  
Author(s):  
Youn Ho Cho ◽  
Won Deok Oh ◽  
Joon Hyun Lee
Keyword(s):  
Long Range ◽  
Guided Waves ◽  
Velocity Dispersion ◽  
Mode Conversion ◽  
Group Velocity Dispersion ◽  
Wave Mode ◽  
Guided Wave ◽  
Wall Thinning ◽  
Theoretical Analyses ◽  
Data Calibration

This study presents a feasibility of using guided waves for a long-range inspection of pipe through investigation of mode conversion and scattering pattern from edge and wall-thinning in a steel pipe. Phase and group velocity dispersion curves for reference modes of pipes are illustrated for theoretical analyses. Predicted modes could be successfully generated by controlling frequency, receiver angle and wavelength. The dispersive characteristics of the modes from and edge wall-thinning are compared and analyzed respectively. The mode conversion characteristics are distinct depending on dispersive pattern of modes. Experimental feasibility study on the guided waves was carried out to explore wall thinning part in pipe for data calibration of a long range pipe monitoring by comb transducer and laser.

scholarly journals Experimental Study on Dispersion Effects of F (1,1) Wave Mode on Thin Waveguide When Embedded with Fluid

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 322
Author(s):  
Nishanth Raja ◽  
Krishnan Balasubramaniam
Keyword(s):  
Low Frequency ◽  
High Sensitivity ◽  
Wave Mode ◽  
Guided Wave ◽  
Liquid Level ◽  
Flexural Mode ◽  
Simultaneous Generation ◽  
Dispersion Effects ◽  
Ultrasonic Guided Wave ◽  
Mode Behavior

This paper reports the simultaneous generation of multiple fundamental ultrasonic guided wave modes L(0,1), T(0,1), and F(1,1) on a thin wire-like waveguide (SS-308L) and its interactions with liquid loading in different attenuation dispersion regimes. An application towards liquid level measurements using these dispersion effects was also demonstrated. The finite element method (FEM) was used to understand the mode behavior and their dispersion effects at different operating frequencies and subsequently validated with experiments. In addition, the ideal configuration for the simultaneous generation of at least two modes (L(0,1), T(0,1), or F(1,1)) is reported. These modes were transmitted/received simultaneously on the waveguide by an ultrasonic shear wave transducer aligned at 0°/45°/90° to the waveguide axis. Level measurement experiments were performed in deionized water and the flexural mode F(1,1) was observed to have distinct dispersion effects at various frequency ranges (i.e., >250 kHz, >500 kHz, and >1000 kHz). The shift in time of flight (TOF) and the central frequency of F(1,1) was continuously measured/monitored and their attenuation dispersion effects were correlated to the liquid level measurements at these three operating regimes. The behavior of ultrasonic guided wave mode F(1,1) when embedded with fluid at three distinct frequency ranges (i.e., >250 kHz, >500 kHz, and >1000 kHz) were studied and the use of low frequency Regime-I (250 kHz) for high range of liquid level measurements and the Regime-II (500 kHz) for low range of liquid level measurements using the F(1,1) mode with high sensitivity is reported.

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

2006 ◽  
Vol 321-323 ◽  
pp. 804-807 ◽  
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.

Time-Frequency Analysis of Partial Discharge Phenomena in SF6 gas using Wavelet Transform

1997 ◽  
Vol 117 (3) ◽  
pp. 338-345 ◽  
Author(s):  
Masatake Kawada ◽  
Masakazu Wada ◽  
Zen-Ichiro Kawasaki ◽  
Kenji Matsu-ura ◽  
Makoto Kawasaki
Keyword(s):  
Wavelet Transform ◽  
Frequency Analysis ◽  
Partial Discharge ◽  
Time Frequency Analysis ◽  
Time Frequency
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