Health Monitoring of Adhesively Bonded Composite Patch Repair of Aircraft Structures using Wavelet Transforms of Lamb Wave Signals
Abstract
In recent years there was a need for developing efficient NDE techniques for large area inspection. Conventional ultrasonic inspection techniques such as C-scan and B-scan are very time consuming because the transducer needs to be scanned over each point of structure under the test. Ultrasonically, Lamb wave is considered to be a candidate for large area inspection based on its capability of propagating long distances and its media-thickness dependent propagation properties. Unfortunately, Lamb wave inspection is complicated by the existence of at least two modes at any given frequency. the received signal generally contains more than one mode, and the proportions of the different modes present is modified by the mode conversion at defects. the modes are also highly dispersive in nature. as a result the peak detection and hence the flaw detection with these ultrasonic signals becomes highly complicated and the interpretation of the signals becomes very difficult and also leads to signal-to-noise problems. Consequently, a new kind of signal analysis is required to interpret the results of inspection and to determine if there is a defect or not. in order to extract the information on defects from the Lamb wave signal received by an ultrasonic transducer in such noisy environments, we use a method of analysis based on wavelet transforms. the detection of ultrasonic pulses using wavelet transforms is described and the robustness of this method is verified with testing on samples of adhesively bonded composite patch repair of cracked aluminum panels with simulated flaws.
Recommended Citation
R. Gubbala and V. S. Rao, "Health Monitoring of Adhesively Bonded Composite Patch Repair of Aircraft Structures using Wavelet Transforms of Lamb Wave Signals," Proceedings of SPIE - The International Society for Optical Engineering, vol. 5056, pp. 33 - 40, Society of Photo-optical Instrumentation Engineers, Nov 2003.
The definitive version is available at https://doi.org/10.1117/12.484658
Department(s)
Electrical and Computer Engineering
Keywords and Phrases
Adhesively bonded composite patch repair; Health monitoring; Lamb waves; NDE; Wavelet transforms
International Standard Serial Number (ISSN)
0277-786X
Document Type
Article - Conference proceedings
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2024 Society of Photo-optical Instrumentation Engineers, All rights reserved.
Publication Date
26 Nov 2003
