Life cycle monitoring could considerably improve the economy and sustainability of composite aircraft components. Knowledge about the quality of a component and its structural health allows thorough exploitation of it’s useful life and offers opportunity for optimization.
Current life cycle monitoring efforts can be split in two main fields 1) process monitoring and 2) structural
health monitoring with little overlap between them. This work aims to propose an integral monitoring approach,
enabling entire life monitoring with the same sensor. First, the state of the art of both composite
manufacturing as well as structural health monitoring technologies is presented. Piezoelectric sensors have
been ruled out for further investigation due their brittleness.
Fiber optical sensors and electrical property-based methods are further investigated. Distributed fiber optic
sensors have been successfully used in composite manufacturing trials. Two processes were demonstrated:
vacuum assisted resin transfer molding and resin infusion under flexible tooling. Due to their flexibility,
optical fibers can survive the loads occurring during manufacturing and deliver valuable insights. It is shown
for the first time numerically and experimentally, that fiber bed compaction levels and volume fractions can
be calculated from the optical frequency shift measured by the optical fiber sensors. The same sensor was
used for subsequent structural health monitoring. This proves that the gap between process monitoring and
structural health monitoring can be closed with mutual benefits in both areas.
The final chapter presents a novel electrical property-based sensing technique. The sensors are highly flexible
and manufactured with a robot-based 3D-printing method. They are shown to reliably work as strain sensors and crack detectors.
This work presents a thorough investigation of available and novel sensing technologies for process monitoring
and structural health monitoring settings. The results obtained could pave the way to more efficient
aircraft structures.Open Acces
