Title: A Comparison of Surface Preparation Techniques for Wind Turbine Field Repairs

Authors: Ariel F. Lusty, Douglas S. Cairns, David A. Miller and Daniel D. Samborsky

DOI: 10.33599/nasampe/s.20.0134

Abstract: Wind turbine service lifetimes can exceed 20 years. This extreme operational demand necessitates reliable and consistent field repairs. However, the effects of current wind turbine field repair surface preparation techniques are not well-documented and are thus not well-understood. This leads to reliance on technician experience rather than scientific data for repair procedures, which causes variability in the quality of repairs. Solvent wiping is a common procedure for contaminant removal after damaged material is removed from a wind turbine blade, but it was unknown if solvent wiping reduces the surface energy and consequently the likelihood of a durable repair. The goal of this study was to quantify the effects various surface preparation techniques have on the overall strength and reliability of wind turbine repairs. Type of reagent-grade solvent, fiber direction, matrix, and adhesive were varied for contact angle and lap shear testing. It was found that the type of solvent used affects neither the surface energy nor the maximum lap shear stress, but the fiber direction and matrix-adhesive combinations significantly affected maximum lap shear stress values.

References: [1] L. C. Dorworth, “Repairs for Advanced Composite Structures,” in Automotive Composites Conference and Exhibition, 2013. [2] L. C. Dorworth, G. L. Gardiner, and G. M. Mellema, Essentials of Advanced Composite Fabrication and Repair. Aviation Supplies & Academics, Inc., 2009. [3] H. Y. Erbil, Surface Chemistry of Solid and Liquid Interfaces. Oxford, UK: Blackwell Publishing Ltd, 2006. [4] R. G. Dillingham and B. R. Oakley, “Surface Energy and Adhesion in Composite–Composite Adhesive Bonds,” J. Adhes., vol. 82, no. 4, pp. 407–426, 2006. [5] D. M. Mattox, “Chapter 2 - Substrate (‘Real’) Surfaces and Surface Modification,” D. M. B. T.-H. of P. V. D. (PVD) P. (Second E. Mattox, Ed. Boston: William Andrew Publishing, 2010, pp. 25–72. [6] F. C. Campbell, “Manfacturing Processes for Advanced Composites.” New York : Elsevier, New York, 2004. [7] B. Duncan and L. Crocker, “Review of Tests for Adhesion Strength,” National Physics Laboratory Materials Centre, Teddington, Middlesex, UK, 2001. [8] K. B. Katnam, A. J. Comer, D. Roy, L. F. M. da Silva, and T. M. Young, “Composite Repair in Wind Turbine Blades: An Overview,” J. Adhes., vol. 91, no. 1–2, pp. 113–139, 2015. [9] D. Y. Kwok and A. W. Neumann, “Contact Angle Measurement and Contact Angle Interpretation,” Adv. Colloid Interface Sci., 1999. [10] L. J. Hart-Smith, R. W. Ochnsner, and R. L. Radecky, “Surface Preparation of Composites for Adhesive-Bonded Repair,” in Engineered Materials Handbook: Adhesives and Sealants, ASM International, 1990. [11] ASTM Standard D5868-01, 2014, “Standard Test Method for Lap Shear Adhesion for Fiber Reinforced Plastic (FRP) Bonding.” ASTM International, West Conshohocken, PA, 2014, DOI: 10.1520/D5868-01R14, www.astm.org.

Conference: SAMPE 2020 | Virtual Series

Publication Date: 2020/06/01

SKU: TP20-0000000134

Pages: 11

Price: FREE