Dynamic behaviour of composite panels under acoustic loading
International Journal of Structural Integrity
ISSN: 1757-9864
Article publication date: 25 November 2019
Issue publication date: 26 August 2020
Abstract
Purpose
There are structural elements on the aircraft that may be exposed to high-intensity sound levels. One of them is an air inlet duct of the jet engine. To prepare data for the air duct damage tolerance analysis, flat panels were tested under acoustic loading. The paper aims to discuss this issue.
Design/methodology/approach
The acoustic fatigue test equipment for grazing wave’s incidence was designed based on the FE analyses. Flat composite panels were designed and manufactured using the Hexply 8552/AGP193-PW prepreg with the simulation of production imperfections or operational damage. The dynamic behaviour of panels has been tested using three regimes of acoustic loading: white noise spectrum, engine noise spectrum and discrete harmonic frequencies. The panel deflection was monitored along its longitudinal axis, and the ultrasonic NDT instruments were used for the monitoring of relevant delamination increments. The FE model of the panel was created in Abaqus to study panel dynamic characteristics.
Findings
No delamination progress was observed by NDT testing even if dynamic characteristics, especially modal frequency, of the panel changed during the fatigue test. Rayleigh damping coefficients were evaluated for their use in FE models. Significant differences were found between the measured and computed panel deflection curves near the edge of the panel.
Originality/value
The research results underscored the signification of the FE model boundary conditions and the element type selections when the panel works like a membrane rather than a plate because of their low bending stiffness.
Keywords
Acknowledgements
The project TE02000032 Advanced Aerostructures Research Centre is solved with the financial support of the Technology Agency of the Czech Republic (TA CR). This paper is based upon a conference paper “Effect of interlaminar flaw on composite panel behaviour under acoustic loading”, hosted on www.matec-conferences.org
Citation
Běhal, J. and Zděnek, P. (2020), "Dynamic behaviour of composite panels under acoustic loading", International Journal of Structural Integrity, Vol. 11 No. 5, pp. 710-722. https://doi.org/10.1108/IJSI-10-2018-0066
Publisher
:Emerald Publishing Limited
Copyright © 2019, Emerald Publishing Limited