Structural health monitoring of fatigue degradation in fibre-reinforced polymers

Parts made of fibre-reinforced polymers (FRPs) as aircraft wings or wind turbine blades are designed for high-load levels, which can lead to progressive damage and, consequently, to the degradation of the mechanical properties during the product life. Health monitoring is essential for detecting the internal damage and thus to improve the in-service reliability and lifetime of FRP structures. Many different types of sensors and techniques for damage sensing and detection have been developed in the years. Compared with other methods, damage monitoring of advanced composites via electrical methods has emerged as a promising approach, being carried out to exploit the intrinsic self-sensing capabilities of the material. Indeed, the presence of conductive fillers in FRPs (for example, carbon fibres or carbon nanoparticles, just to mention a few) results in a conductive network. Service load-induced damage interrupts this network, thus increasing the electrical resistance of the material, which can be used as an effective parameter to quantify the health state of the component. The aim of this chapter is to present a comprehensive overview on the electrical health monitoring of FRP parts. In particular, the possible damage events being monitored and the associated strategies to be used will be discussed in detail. Moreover, the available modelling approaches to correlate electrical measurements with the damage state and the residual mechanical properties, as well as the implementation difficulties to be overcome when moving from laboratory specimens to industrial composite parts, will be introduced.

Subjects

Damage

Electrical methods

Structural health monitoring

DDC Class

600: Technology

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Structural health monitoring of fatigue degradation in fibre-reinforced polymers