Barely visible impact damage detection in aerospace-grade carbon fibre reinforced polymer components with optical fibre sensors

Student thesis: Doctoral Thesis


Optical fibre-based sensors have shown great potential for damage detection in
composite aircraft components, but demonstrations of this technology have
been mostly limited to laboratory experiments carried out in ideal environmental
conditions. In my PhD research, I take this technology to the next level and deal
with different practicalities that need to be considered when working in actual
aerospace-grade environments.
First, I have investigated the embedding of optical fibre sensors within the
layers of a composite panel. On top of that, I have also developed a method for
mounting optical fibre sensors onto the surface of aerospace-grade composite
components in a robust manner. I have verified that this type of sensor and its
installation method remain unaffected by harsh in-flight conditions. While
considering on-ground conditions, I have derived thresholds and radii that must
be respected when attempting to detect damage. In addition, I have
investigated how specialty optical fibre sensors can improve the detection of
complex ultrasonic waves which are often used to support the damage
inspection of large composite components.
Second, I have demonstrated that the above-mentioned in-flight compatible
installation method and the practical damage detection methodology are also
compatible with installation in damage-prone regions of more complex
components. More specifically, I have verified the previous findings on larger
and realistic component geometries, including the feet of two omega-stiffeners,
a 3 m long C-shaped floor beam and two window frames.
Third and finally, I have developed a figure of merit that quantifies the health of
a full-scale composite component based on the signals of a network of optical
fibre sensors. This so-called global damage index allows an end user to easily
assess the health condition of the inspected component and to keep track of
how this health status evolves throughout the lifetime of the component.
The achievements of my PhD research have demonstrated the potential and
practical considerations of using the optical fibre sensing technology at
increased technology readiness level for applications in the aerospace industry.
By doing so, I hope to have contributed to enabling safer, more cost-efficient,
sustainable and eco-friendlier aviation.
Date of Award8 Jun 2021
Original languageEnglish

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