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Estimation of porosity and moisture content in polymer composites using thermo-acoustic waves

Bhat, MR and Roy, MD (2017) Estimation of porosity and moisture content in polymer composites using thermo-acoustic waves. In: 24th International Congress on Sound and Vibration, ICSV 2017, 23 - 27 July 2017, London.

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Official URL: https://www.iiav.org/index.php?va=viewpage&vaid=26


Experimental investigations were carried out for non-destructive evaluation (NDE) of porosity and moisture content in polymer composite materials. In this study, porosity of varied levels were induced in the carbon fiber reinforced epoxy polymer (CFRP) composite laminates by varying the fabrication parameters such as applied vacuum, autoclave pressure and curing temperature. Further, the composite laminates with varied porosity levels were subjected to different humidity and temperature conditions to study the hygro-thermal effects. Degradation of the composite materials due to varied porosity contents and then further due to moisture absorption were investigated through series of experimental tests in the laboratory using ultrasonic imaging and acoustic wave velocity and attenuation measurements. Acoustic wave propagation was stimulated by mechanical point source as well as by giving high power LASER shots using a Q-switched Nd-Yag pulse laser system. Waves thus generated from the center region of the laminates were picked up by highly sensitive PZT sensors placed at four corners. Changes in wave characteristics as they propagate across the laminates of different porosity and moisture content were studied. NDE parameters such as ultrasonic attenuation coefficients, changes in acoustic wave propagation characteristics etc., were studied with regard to different extents of porosity content and different degree of hygro-thermal degradation. The different sets of experimental investigations have yielded encouraging results. Acoustic wave propagation studies using lead pencil breakage as well as non - contact LASER source show that the wave attenuation characteristics can be correlated to variation in the porosity and moisture content in the composite laminates.

Item Type: Conference Paper
Publication: 24th International Congress on Sound and Vibration, ICSV 2017
Publisher: International Institute of Acoustics and Vibration, IIAV
Additional Information: The copyright for this article belongs to the International Institute of Acoustics and Vibration, IIAV.
Keywords: Acoustic wave velocity; Acoustic waves; Acoustics; Carbon; Composite materials; High power lasers; Laminated composites; Laminates; Moisture; Moisture determination; Nondestructive examination; Polymers; Porosity; Ultrasonic imaging; Ultrasonic testing, Attenuation measurements; Carbon fiber reinforced; Experimental investigations; Humidity and temperatures; Non destructive evaluation; Polymer composite materials; Ultrasonic attenuation; Wave propagation characteristics, Acoustic wave propagation
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 25 Jul 2022 11:38
Last Modified: 25 Jul 2022 11:38
URI: https://eprints.iisc.ac.in/id/eprint/74747

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