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Shock and Vibration
Volume 2015 (2015), Article ID 561238, 7 pages
Research Article

Machinery Fault Diagnosis Using Two-Channel Analysis Method Based on Fictitious System Frequency Response Function

1Department of Mechanical & Automotive Engineering, Andong National University, 388 Songcheon-Dong, Andong 760-749, Republic of Korea
2Department of Mechanical Design, Andong National University, 388 Songcheon-Dong, Andong 760-749, Republic of Korea

Received 8 January 2015; Revised 7 April 2015; Accepted 17 April 2015

Academic Editor: Roger Serra

Copyright © 2015 Kihong Shin and Sang-Heon Lee. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Most existing techniques for machinery health monitoring that utilize measured vibration signals usually require measurement points to be as close as possible to the expected fault components of interest. This is particularly important for implementing condition-based maintenance since the incipient fault signal power may be too small to be detected if a sensor is located further away from the fault source. However, a measurement sensor is often not attached to the ideal point due to geometric or environmental restrictions. In such a case, many of the conventional diagnostic techniques may not be successfully applicable. In this paper, a two-channel analysis method is proposed to overcome such difficulty. It uses two vibration signals simultaneously measured at arbitrary points in a machine. The proposed method is described theoretically by introducing a fictitious system frequency response function. It is then verified experimentally for bearing fault detection. The results show that the suggested method may be a good alternative when ideal points for measurement sensors are not readily available.