From Event: SPIE Commercial + Scientific Sensing and Imaging, 2017
The use of wide frequency band piezoelectric transducers in ultrasonic infrared thermography allows analyzing material structural defects under low power ultrasonic stimulation compared to single-frequency stimulation which is performed, for example, by means of powerful magnetostrictive stimulation. Defect resonance frequencies can be determined through the detailed analysis of material surface vibrations by using a technique of laser vibrometry in a wide range of frequencies. This paper describes the approach to analyze ultrasonic resonances in samples with hidden defects by using resonant piezoelectric transducers. The effectiveness of the method is assessed by discussing some key examples of impact damaged graphite/epoxy composite samples hybridized with flax fibers. Optical and powerful ultrasonic stimulation have been also used as alternative inspection techniques.
D. A. Derusova, V. P. Vavilov, S. Sfarra, F. Sarasini, N. V. Druzhinin, and V. O. Nekhoroshev, "Highly efficient ultrasonic vibrothermography for detecting impact damage in hybrid composites," Proc. SPIE 10214, Thermosense: Thermal Infrared Applications XXXIX, 102140N (Presented at SPIE Commercial + Scientific Sensing and Imaging: April 12, 2017; Published: 5 May 2017); https://doi.org/10.1117/12.2262423.
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