DocumentCode :
2694407
Title :
Effects of inclined incidence on ultrasonic testing of a closed crack
Author :
Okamoto, Tatsuaki ; Kurihara, Keiichirou ; Sugiura, Toshihiko
Author_Institution :
Dept. of Mech. Eng., Keio Univ., Yokohama, Japan
fYear :
2012
fDate :
7-10 Oct. 2012
Firstpage :
1445
Lastpage :
1448
Abstract :
Detection and sizing of a closed crack are difficult by the conventional ultrasonic testing, because ultrasonic waves propagate through a closed crack. Recently, the nonlinear ultrasonic testing using superharmonics and/or subharmonics is regarded as a remarkable method of detecting a closed crack. However, the mechanism of subharmonics generation by a closed crack is not clear yet. In this study, we investigated propagation of inclined incident ultrasonic waves through a closed crack and introduced a two-dimensional model with reference of a one-dimensional model which we had introduced in our previous study (Kurihara, et al, 2011). In our experiments, after first finding natural frequencies from frequency response curves, we analyzed received signals obtained under the excitation frequencies twice the natural frequencies, using the Wavelet transformation. From the experimental results, subharmonics generation as well as the natural frequencies were influenced by the incident angles and the compression forces. Considering these results, we introduced a two-dimensional model with nonlinear springs. This model gives us numerical results corresponding with the experimental ones. Consequently, this two-dimensional model can be essential to understand the mechanism of subharmonics generation at a closed crack under inclined incidence of ultrasonic waves.
Keywords :
acoustic signal processing; crack detection; mechanical engineering computing; numerical analysis; springs (mechanical); ultrasonic materials testing; ultrasonic propagation; wavelet transforms; closed crack detection; closed crack sizing; compression forces; excitation frequencies; frequency response curves; inclined incident ultrasonic wave propagation; natural frequencies; nonlinear springs; numerical analysis; one-dimensional model; signal analysis; subharmonic generation mechanism; two-dimensional model; ultrasonic testing; wavelet transformation; Acoustics; Numerical models; Oscillators; Springs; Surface cracks; Testing; Time-frequency analysis; Closed Crack; Nonlinear Ultrasonics; Subharmonic; Ultrasonic Testing;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Ultrasonics Symposium (IUS), 2012 IEEE International
Conference_Location :
Dresden
ISSN :
1948-5719
Print_ISBN :
978-1-4673-4561-3
Type :
conf
DOI :
10.1109/ULTSYM.2012.0361
Filename :
6562404
Link To Document :
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