Session: 02-11-01 Reliability Based Maintenance

Submission Number: 178191

Advanced Material Strategies for Tidal Turbine Blades: From Structural Validation to Marine Durability 

The commercial viability of tidal energy is strongly linked to reducing the levelised cost of energy while ensuring the long-term reliability of tidal energy converters. Among all structural components, turbine blades remain the most critical, due to their continuous exposure to cyclic hydrodynamic loads, long-term seawater immersion, erosion, biofouling, and potential impact from floating debris. These harsh operating conditions demand advanced material solutions capable of maintaining structural integrity, reducing maintenance frequency, and extending service life. Within this background, the development of durable and cost-effective tidal turbine blades is essential to boosting the full potential of tidal Stream Energy as a reliable renewable resource. Current industry practice relies on small- to full-scale dry laboratory structural testing programmes to validate new blade design strategies and ensure compliance with DNV-ST-0164 and IEC TS 62600-3 standards. However, blades deployed in marine environments are exposed to a complex set of degradation mechanisms including water absorption, cavitation erosion, corrosion, and biofouling that progressively compromise structural integrity and shorten service life. Conventional dry laboratory testing does not fully replicate these environmental phenomena, creating a critical gap between laboratory validation and in-service performance. Addressing this gap, the present research investigates the structural performance and accelerated aging behaviour of advanced composite tidal turbine blades, with a focus on enhancing durability and ensuring economic viability.

A full-scale tidal turbine blade with a span of 5 m was manufactured from carbon fibre prepreg composites using a hand layup process, followed by autoclave curing, and subsequently subjected to structural testing in compliance with the DNV-ST-0164 and IEC TS 62600-3 standards. The structure is referred to as a tidal turbine foil instead of a tidal turbine blade, owing to its helical shape, which differentiates it from traditional straight-bladed designs. In this study, only static tests were performed under idealised loading conditions, with loads applied at the cantilever tip and the midsection of the tidal turbine foil. The resulting data were used to validate a finite element (FE) model. This validation confirms that the FE model can capture the strain distribution of the blade, providing a robust platform for further exploration of material configurations. Building on this, two additional laminate systems were considered for tidal turbine foil manufacturing: one manufactured using prepreg hand layup and another using vacuum-assisted resin transfer moulding techniques. All three material systems utilised advanced carbon fibre composites with different ply stacking sequences, fibre architectures, and ply thicknesses, designed to achieve an equivalent overall laminate thickness for the tidal turbine foils. The objective was to identify the most suitable material system and layup schedule for tidal turbine foils. Structural testing and FE modelling under idealised loading demonstrated that all three laminates exhibited comparable strain distribution behaviour, indicating that material differences are not critical under idealised loading conditions. However, long-term durability in harsh marine environments remains the decisive factor in material selection for future tidal turbine blade applications.

To bridge this gap, an accelerated aging study was conducted on coupons manufactured from the same materials as the full-scale foils. These coupons were evaluated for water absorption to assess marine exposure effects on the individual composite materials, allowing direct comparison of mechanical degradation rates across the three systems. The results provide crucial insights into the role of manufacturing techniques, fibre architectures, and laminate configurations in resisting moisture ingress and retaining mechanical performance under predicted service conditions. This integrated experimental numerical approach not only validates structural performance under standardised loading but also addresses the pressing challenge of durability in marine environments. By combining full-scale validation with accelerated aging studies, the research identifies the most reliable composite system for future tidal turbine blade manufacturing. The outcomes contribute to extending blade service life, reducing maintenance costs, and ultimately improving the economic competitiveness of tidal energy.

Presenting Author: Tenis Ranjan Munaweera Thanthirige University of Galway

Presenting Author Biography: Dr. Tenis Ranjan is a Research Associate in Civil Engineering at the University of Galway. He holds a Bachelor of Science (BSc), a Master of Philosophy (MPhil) in Mechanical and Manufacturing Engineering, and a PhD in Civil Engineering, reflecting his strong interdisciplinary academic background.

Dr. Ranjan’s research expertise encompasses composite manufacturing, structural testing, and Finite Element Analysis (FEA), with a particular focus on tidal and wind turbine blades. His current work aims to enhance the structural performance and integrity of tidal turbine blades through a combination of experimental testing, numerical simulations, and predictive modeling. He is particularly interested in developing fatigue life and residual strength models to assess blade degradation and performance in demanding marine environments.

Before pursuing his doctoral studies, Dr. Ranjan served as a lecturer for seven years at the University of Ruhuna in Sri Lanka, where he taught courses in composite materials and manufacturing, thermodynamics, fluid dynamics, and machine design. This experience reflects his deep commitment to teaching and knowledge dissemination.

With his interdisciplinary expertise bridging mechanical and civil engineering, Dr. Ranjan brings a unique perspective to advancing renewable energy technologies and promoting sustainable engineering solutions.

Authors:

Tenis Ranjan Munaweera Thanthirige University of Galway
Michael Flanagan University of Galway
Ciaran Kennedy University of Galway
Clement Courade ORPC Ireland
Patrick Cronin ORPC Ireland
Jeffwin George Composites Testing Laboratory
Michael Walls Composites Testing Laboratory
Edward M. Fagan Zero Nexus Inc
Jamie Goggins University of Galway
William Finnegan University of Galway