Abstract

Fibres and composites are an essential part of developments to commercialize marine renewable energy.
Intervention at sea for maintenance or repair is expensive and high-risk; so long term reliability is a priority.
Polymer and composite components for marine energy recovery systems are numerous, and include
mooring lines, dynamic cables, turbine blades (for tidal and floating wind) and various protection elements.
Work at IFREMER in recent years has focussed on the long term behaviour of these materials and this
presentation will discuss two examples: synthetic fibre mooring lines and composite tidal turbine blades.
Fibre ropes can be considered as composites without the matrix, but in most marine applications the
coatings applied to fibre yarns are critical to guarantee long term durability¹.For floating wind either
HMPE (high modulus polyethylene) or nylon fibre ropes are employed, according to the type of floater, and
both show a particular response under tensile loading. Their behaviour results from a combination of fibre
properties, rope construction and loading history. These structures have received little academic attention
but a thorough understanding of their properties is essential in order to design a reliable floating wind
turbine.

The second example will discuss composite tidal turbine blades. A recent study funded by the EU Horizon
programme, RealTide², provided us with the opportunity to perform tests on full size carbon fibre
reinforced blades. This required design and manufacture of a specific test set-up, instrumentation of the
blades (over 100 measuring points) and testing to failure. Results from tests and numerical modelling will
be presented and alternative materials options will be discussed.

References

1. Y. Chevillotte et al, Fatigue of improved polyamide mooring ropes for floating wind turbines, Ocean Engineering, 199, 107011 (2020)
2. P. Davies et al., Material and structural testing to improve composite tidal turbine blade reliability, International Marine Energy Journal, vol.5, 1, (2022)

Location: Building 19, Level 3, Hall 1-2.