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A comparative study of experimental and finite element analysis on submillimeter flaws by laser and ultrasonic excited thermography

: Zhang, H.; Fernandes, H.; Yu, L.; Hassler, U.; Genest, M.; Robitaille, F.; Joncas, S.; Sheng, Y.; Maldague, X.


Zalameda, J.N. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Thermosense: Thermal Infrared Applications XXXVIII : 18-21 April 2016, Baltimore, Maryland, United States
Bellingham, WA: SPIE, 2016 (SPIE Proceedings 9861)
ISBN: 978-1-5106-0102-4
Art. 98611A
Conference "Thermosense - Thermal Infrared Applications" <38, 2016, Baltimore/Md.>
Conference Paper
Fraunhofer IIS ()

Stitching is used to reduce dry-core and reinforce T-joint structure. However, it might cause new types of flaws, especially submillimeter flaws. In this paper, new approaches including micro-VT, lock-in micro-LLT and micro-LST based on both lock-in and pulse methods are used to detect submillimeter flaws in stitched CFRP. A comparison of laser excitation thermography and micro-VT on micro-porosities is conducted. Micro-CT is used to validate the infrared results. Then, a finite element analysis (FEA) is performed. The geometrical model needed for finite element discretization was developed from micro-CT measurements. The model is validated for the experimental results. Finally a comprehensive experimental and simulation comparison of micro-LLT and micro-LST based on both lock-in and pulse methods is conducted.