Technologies of Wind Turbine Blade Repair: Practical Comparison

Abstract

Maintenance and repair of wind turbines contribute to the higher costs of wind energy. In this paper, various technologies of structural repair of damaged and broken wind turbine blades are compared. The composite plates, mimicking damaged blade parts, were damaged and repaired, using various available curing and bonding technologies. Technologies of repair with hand layup lamination, vacuum repair with hand layup and infusion, ultraviolet repair and high temperature thermal curing were compared. The repaired samples were tested under tensile static and fatigue tests, and subject to microscopic X-ray investigations. It was observed that both the strength of the repaired structures and the porosity depend on the repair technology used. Vacuum-based technologies lead to relatively stiff and lower-strength repaired plates, while ultraviolet-curing technologies lead to average stiffness and high strength. High-temperature vacuum curing leads to the highest maximum stress. Hand layup (both vacuum and without vacuum) leads to high post-repair porosity in the adhesive and scarf, while vacuum infusion leads to low porosity. Fatigue lifetime generally follows the trend of porosity. There exist risks of micro-damaging the parent laminate and the formation of residual stresses in the repaired structure.

Repair of Wind Turbine Blades: Costs and Quality

“…Figure 3 shows the test samples. Figure 4 shows relative maximum failure stress for various repair cases, normalized by the failure stress of virgin (unrepaired) samples [9]. From the data on Figure 4, one can draw the following conclusions.…”

“…For handheld UV curing, both small and medium sized air bubbles in the bundles, and large and more spherical air bubbles between bundles are available. More details on this experimental program are given in [9] The main conclusion of this section (and a more detailed study presented in [9]) is that different technologies of blade repair lead to different porosities in the adhesives and scarf. General observation is that all the technologies give relative good quality of repair with view on static strength.…”

Quantification of process-induced effects on fatigue life of short-glass-fiber-filled adhesive used in wind turbine rotor blades

“…Cracks in adhesive joints of wind turbine rotor blades can often cause structural damage [1]. During operation, tunneling cracks can be initiated in the adhesive layer, and propagate into the surrounding laminate, making structural repairs necessary [2].…”

Scalable MXene and PEDOT-CNT Nanocoatings for Fibre-Reinforced Composite De-Icing

“…Ice formation on the blades is one of the most severe problems, causing disturbed aerodynamic flow and reducing the wind turbine’s efficiency by up to 20% [ 4 , 5 ]. Additionally, it can cause excessive vibrations, unequal load distribution, and ice debris can damage the composite structures [ 6 , 7 ], leading to higher maintenance costs [ 8 ]. Ice preventing systems, so-called anti-icing, are based on various hydrophobic coatings, whereas de-icing is based on active heating using embedded heaters or hot air tubing [ 9 , 10 ].…”