Mechanical evaluation of repair resins for fiber-glass wind turbine blades

Abstract

This paper contains details of mechanical testing of double cantilever beam composite specimens comprising a vacuum-assisted resin transfer molding–infused parent plate and a hand laid-up upper plate simulating a typical blade repair. The testing was carried out as part of an effort to optimize a new repair resin for a wind turbine blade manufacturing company. A number of commercial suppliers were contacted and nine resins with different formulations were selected for screening. Out of these, six were shortlisted for initial testing which was carried out in accordance with ASTM D 5528 (Test Method for Mode I interlaminar fracture toughness of unidirectional fiber-reinforced polymer matrix composites) using double cantilever beam specimens. The fracture toughness values obtained from testing these repair resin candidates were compared to values obtained from the repair resin currently being used and also to those of the main blade resin. The top three repair resin candidates were identified from the double cantilever beam testing.

Aeroelastic vibration analysis of wind turbine blade with Gurney flap

“…In aeroelastic vibration analysis, blades can be simplified or equivalent to beam models, including the cantilever beam 24 and the thin-wall beam, 25 since they have similar mechanical action frame and main structure. In this section, based on the structural characteristics of the blade, we develop the equivalent model to obtain the frequency characteristics of the main body of the blade, instead of the previous method of directly giving the natural frequency value.…”

“…To analyze the thin-walled rotor blade better, frequency terms are added in the solution of the above motion equation. Add frequency term, x 2 mz to the motion equation of flap direction, and add frequency term x 2 K 2 m mu in torsion direction, which can be calculated by equations (24) to (26).…”

Experimental Study of Stepped-Lap Scarf Joint Repair for Spar Cap Damage of Wind Turbine Blade in Service

“…As the service year increases, the hidden defects gradually show up [2,3]. Being affected by environmental corrosion, manufacturing defects, insufficient design, aging of materials, and overload [4,5], the hidden defects eventually appear as different failure modes [6] (such as fiber fracture, matrix failure, delamination, etc.) and damage types [7] (such as adhesive joint failure between skins, sandwich panel face/core debonding, gelcoat cracks, etc.).…”