Presentations

Abstract

Wind turbine blades are large composite structures where adhesive bonds play a critical structural role, connecting shells, spar caps, and shear webs. A single 140 m blade can contain up to 800 m of adhesive bond lines. While blade failures are rare, adhesive bond failures are among the leading causes when they occur, often resulting in significant consequences. This paper consolidates insights from extensive blade failure investigations and factory assessments to identify common failure modes, causal factors, and strategies for risk reduction. The study highlights that most failures are not due to design or material selection but to manufacturing process variability, particularly in surface preparation and adhesive application. Common defects include inadequate grinding, contamination, and improper timing between surface preparation and bonding. Adhesive geometry flaws, such as insufficient bond width or voids, also contribute to failures. Post-failure analysis reveals that cohesive failures generally indicate bonds meeting specifications, whereas smooth adhesive surfaces suggest weak adhesion. To mitigate risks, the paper recommends enhanced process controls, improved environmental conditions, automation of adhesive application, and better surface preparation methods, potentially inspired by aerospace practices. Additionally, the authors emphasize the need for design-for-manufacturing approaches and verification of bond performance across process variability. Implementing these measures can significantly improve blade reliability and reduce the likelihood of catastrophic failures.