Articles | Volume 2, issue 2
Wind Energ. Sci., 2, 641–652, 2017
Wind Energ. Sci., 2, 641–652, 2017

Research article 19 Dec 2017

Research article | 19 Dec 2017

Effects of defects in composite wind turbine blades – Part 1: Characterization and mechanical testing

Jared W. Nelson1, Trey W. Riddle2, and Douglas S. Cairns3 Jared W. Nelson et al.
  • 1SUNY New Paltz, Division of Engineering Programs, New Paltz, NY, USA
  • 2Sunstrand, LLC, Louisville, KY, USA
  • 3Montana State University, Dept. of Mechanical and Industrial Engineering, Bozeman, MT, USA

Abstract. The Montana State University Composite Material Technologies Research Group performed a study to ascertain the effects of defects that often result from the manufacture of composite wind turbine blades. The first step in this multiyear study was to systematically quantify and enter these defects into a database before embedding similar defects into manufactured coupons. Through the Sandia National Laboratories Blade Reliability Collaborative (BRC), it was determined that key defects to investigate were fiber waves and porosity. An inspection of failed commercial-scale wind turbine blades yielded metrics that utilized specific parameters to physically characterize a defect. Methods to easily and consistently discretize, measure, and assess these defects based on the identified parameters were established to allow for statistical analysis. Data relating flaw parameters to frequencies of occurrence were analyzed and found to fit within standard distributions. Additionally, mechanical testing of coupons with flaws based on these physical characterization data was performed to understand effects of these defects. Representative blade materials and manufacturing methods were utilized and both material properties and damage progression were measured. It was observed that flaw parameters directly affected the mechanical response. While the data gathered in this first step are widely useful, it was also intended for use as a foundation for the rest of the study, to perform probabilistic analysis and comparative analysis of progressive damage models.

Short summary
Given the rapid growth and large scale of wind turbines, it is important that wind farms achieve maximum availability by reducing downtime due to maintenance and failures. The Blade Reliability Collaborative, led by Sandia National Laboratories and sponsored by the US DOE, was formed to address this issue. A comprehensive study to characterize and understand the manufacturing flaws common in blades, and their impact on blade life, was performed by measuring and testing commonly included defects.