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Proceedings Paper

Detection of fatigue crack on a rotating steel shaft using air-coupled nonlinear ultrasonic modulation
Author(s): Byeongju Song; Byeongjin Park; Hoon Sohn; Cheol-Woo Lim; Jae-Roung Park
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Paper Abstract

Rotating shafts in drop lifts of manufacturing facilities are susceptible to fatigue cracks as they are under repetitive heavy loading and high speed spins. However, it is challenging to use conventional contact transducers to monitor these shafts as they are continuously spinning with a high speed. In this study, a noncontact crack detection technique for a rotating shaft is proposed using air-coupled transducers (ACTs). (1) Low frequency (LF) and high frequency (HF) sinusoidal inputs are simultaneously applied to a shaft using two ACTs, respectively. A fatigue crack can provide a mechanism for nonlinear ultrasonic modulation and create spectral sidebands at the modulation frequencies, which are the sum and difference of the two input frequencies Then LF and HF inputs are independently applied to the shaft using each ACT. These three ultrasonic responses are measured using another ACT. (2) The damage index (DI) is defined as the energy of the first sideband components, which corresponding to the frequency sum and difference between HF and LF inputs. (3) Steps 1 and 2 are repeated with various combinations of HF and LF inputs. Crack existence is detected through an outlier analysis of the DIs. The effectiveness of the proposed technique is investigated using a steel shaft with a real fatigue crack.

Paper Details

Date Published: 24 April 2015
PDF: 9 pages
Proc. SPIE 9435, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, 943513 (24 April 2015); doi: 10.1117/12.2084982
Show Author Affiliations
Byeongju Song, KAIST (Korea, Republic of)
Byeongjin Park, KAIST (Korea, Republic of)
Hoon Sohn, KAIST (Korea, Republic of)
Cheol-Woo Lim, KIA Motors Hwasung Plant (Korea, Republic of)
Jae-Roung Park, KIA Motors Hwasung Plant (Korea, Republic of)

Published in SPIE Proceedings Vol. 9435:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015
Jerome P. Lynch, Editor(s)

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