Structural Health Monitoring of Composite Scarf Repairs with Guided Waves

Abstract:

The interest in composite repair technologies has been recently increased following the wide applications of composite materials in aerospace industry. Bonded patch repair technologies provide an alternative to mechanically fastened repairs with significantly higher performance. Scarf repairs offer great advantages compared to external patch repairs since they provide higher stiffness by matching ply to ply the original structure and by reducing stress discontinuities in the repaired region. Ultrasonic guided waves have been extensively used for the health monitoring of complex structures due to their remarkable ability of defect recognition. The authors have previously investigated the extraction of the instantaneous characteristics of Lamb waves for the monitoring of an aluminium repaired structure, highlighting the potential use of such waves in the inspection of repaired structures [1]. In the current study, the behaviour of a scarf repair was monitored with guided ultrasonic waves excited by low profile, surface bonded piezoceramic transducers under longitudinal tensile loading. Appropriate damage indices were extracted and the results were correlated with images taken through a 3-Dimensional Digital Image Correlation (3-D DIC) technique. The correlation of the extracted features with the early stage damage is performed and conclusions about the recovered strength through the scarf repair are deduced. Finally the study compares results obtained from the on-line analysis and from off-line techniques such as ultrasonic C-scanning and X-ray radiography.

• Periodical: Key Engineering Materials (Volume 518)
• Pages: 328-337
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.518.328
• Online since: July 2012
• Authors: Sofia Pavlopoulou, Costas Soutis, Wieslaw Jerzy Staszewski
• Keywords: Digital Image Correlation (DIC), Guided Ultrasonic Waves, Nondestructive Testing (NDT), On-Line Structural Health Monitoring, Scarf Repair

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