PSI - Issue 5

K.S.C. Kuang et al. / Procedia Structural Integrity 5 (2017) 1168–1175 Dong Yang et al. / Structural Integrity Procedia 00 (2017) 000 – 000

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4. Conclusion

The paper has presented a POF sensor based method to monitor crack initiation and propagation under fatigue loading. In order to extract the feature associated with crack initiation and propagation, RMS envelope and Hilbert transfer-based filter extracted the envelope and high frequency components embedded in the POFs sensor signal by decomposing the raw data obtained under fatigue loading. The resulting envelope plot was shown to be effective in tracking the crack propagation in the steel structures. In addition, analysis of the high frequency component data, it was demonstrated that the increasing amplitude level could infer as crack initiation while further increase in the amplitude readings were indicative of progressive crack propagation. To validate the POFs sensor, AE sensors was used to detect and monitor the fatigue crack of the specimen. The study highlights the potential of the POFs sensor in monitoring crack initiation and propagation under cyclic fatigue loading. DOEBLING, S. W., FARRAR, C. R., PRIME, M. B. & SHEVITZ, D. W. 1996. Damage identification and health monitoring of structural and mechanical systems from changes in their vibration characteristics: A literature review. Shock & Vibration Digest, 30 , 2043-2049. DOEBLING, S. W., FARRAR, C. R. & PRIME, M. B. 1998. A Summary Review of Vibration-Based Damage Identification Methods. Shock & Vibration Digest, 30 , 91-105. SOHN, H., FARRAR, C. R., HEMEZ, F. M. & CZARNECKI, J. J. 2002. A Review of Structural Health Review of Structural Health Monitoring Literature 1996-2001. Data Acquisition, la-13976-m. FARRAR, C. R. & WORDEN, K. 2007. An introduction to structural health monitoring. Philosophical Transactions of the Royal Society A Mathematical Physical & Engineering Sciences, 365 , 303. FAN, W. & QIAO, P. 2010. Vibration-based Damage Identification Methods: A Review and Comparative Study. Structural Health Monitoring, 9 , 83-111. TUA, P. S., QUEK, S. T. & WANG, Q. 2004. Detection of cracks in plates using piezo-actuated Lamb waves. Smart Materials & Structures, 13 , 643. OHARA, Y., YAMAMOTO, S., MIHARA, T. & YAMANAKA, K. 2008. Erratum: “Ultrasonic Evaluation of Closed Cracks Using Subharmonic Phased Array”. Japanese Journal of Applied Physics, 47 , 9018-9018. ROBERTS, T. M. & TALEBZADEH, M. 2003. Acoustic emission monitoring of fatigue crack propagation. Journal of Constructional Steel Research, 59 , 695-712. WEEKES, B., ALMOND, D. P., CAWLEY, P. & BARDEN, T. 2012. Eddy-current induced thermography — probability of detection study of small fatigue cracks in steel, titanium and nickel-based superalloy. Ndt & E International, 49 , 47-56. Acknowledgements References