Structural integrity evolution of composite tidal turbine materials : correlating surface roughness with progressive erosive damage

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Habibi, Payvand and Algaddaime, Talal F and Abad, Farhad and Stack, Margaret M and Mehmanparast, Ali and Brennan, Feargal and Lotfian, Saeid (2025) Structural integrity evolution of composite tidal turbine materials : correlating surface roughness with progressive erosive damage. Theoretical and Applied Fracture Mechanics, 139 (Part A). 105076. ISSN 0167-8442 (https://doi.org/10.1016/j.tafmec.2025.105076)

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Abstract

Tidal energy offers significant potential for renewable power generation, but blade erosion threatens turbine reliability over their targeted 25-year service life. This study examines erosion mechanisms in tidal turbine blades, focusing on testing FR4 glass fibre-reinforced polymer (GFRP) composites under accelerated erosion conditions with sand particles (100–150 μm) at 12.5 m/s flow velocity and varying impact angles (30°, 45°, 60°, 90°). Experimental results reveal maximum erosion occurs at 60° impingement angles, with mass losses reaching 0.7 % after a 90-minute exposure, indicating a mixed ductile–brittle erosion response. Surface roughness measurements demonstrate a characteristic W-shaped erosion profile at 90° impingement, with maximum depth variations of 140 μm at 60° impact angles. The study establishes correlations between mass loss and surface roughness parameters, showing that arithmetic mean roughness (Ra) is the least sensitive to erosion, while total roughness height (Rt) exhibits the strongest correlation. The selected roughness parameter (Rz) shows moderate sensitivity, increasing from 40 μm to 150 μm as mass loss progresses from 0.1 % to 0.8 %. Tests conducted with different sand sizes (0–50 μm, 50–100 μm, 100–150 μm) in saltwater (3.5 % salinity) reveal particle size dependence of erosion rates. Surface analysis using 3D optical scanning (10 nm vertical resolution) quantifies progressive damage from microscopic pitting to material removal exceeding 200 μm depth. Computational fluid dynamics simulations at 90° impingement demonstrate stagnation point effects, explaining the characteristic erosion patterns observed. The research highlights that blade hydrodynamic performance may degrade significantly before structural failure, with surface roughening affecting efficiency even at early erosion stages. The review concludes by identifying critical research needs, including the development of erosion-resistant composites, real-time monitoring techniques, and validated numerical models for predicting erosion progression. This comprehensive understanding of erosion mechanisms and their quantified effects is essential for improving tidal turbine reliability and commercial viability.

ORCID iDs

Habibi, Payvand, Algaddaime, Talal F, Abad, Farhad ORCID logoORCID: https://orcid.org/0000-0001-6765-8593, Stack, Margaret M ORCID logoORCID: https://orcid.org/0000-0001-6535-6014, Mehmanparast, Ali ORCID logoORCID: https://orcid.org/0000-0002-7099-7956, Brennan, Feargal ORCID logoORCID: https://orcid.org/0000-0003-0952-6167 and Lotfian, Saeid ORCID logoORCID: https://orcid.org/0000-0001-8542-933X;
CORE (COnnecting REpositories)