Development of an SHM system of sandwich composite panels using guided elastic waves
Abstract »Sandwich structures consisting of two face composite sheets and a honeycomb aluminium core are largely used in some aerospace components for their structural and light weight properties. However, they might be subjected to damages such as delaminations in the composite sheets or debondings between the face sheets and the core due to impacts or thermo-mechanical aging.
We present here the latest studies performed through a collaborative project aiming at developing a guided elastic wave’s based Structural Health Monitoring (SHM) system of such components. These waves can propagate in plate-like structures over large distances without significant attenuation. They allow to monitor wide zones with a limited number of sensors in order to detect, to locate and to characterize defects.
In a first step of the study, the properties of the guided waves propagation in pristine sandwich panels are determined. Different modes are emitted thanks to piezoelectric patches of different diameters bonded at the surface of the plate. Modes characteristics (dispersion curves, attenuation, and anisotropy of the propagation) are determined thanks to laser Doppler velocimetry measurements.
The same experimental setup is then used to highlight interaction of guided waves with calibrated defects of different diameters in sandwich plates (debondings between the face sheet and honeycomb core).
These results allow to select the guided mode and its frequency which is the most sensitive to the defects.
Measurements on a real large scale (3m x 3m) sandwich component are finally presented.
Biography: PhD on guided waves SHM of bonded composite patches prepared at Onera, the French aerospace lab\r\nNDE and SHM project manager at CEA-LIST since 2010
main interests: UT, guided waves, SHM, POD
Affiliation: French Alternative Energies and Atomic Energy Commission (CEA LIST) NDE Department 91191 Gif-sur-Yvette France