Date of Award
2026
Document Type
Open Access Dissertation
Degree Name
Doctor of Philosophy in Mechanical Engineering-Engineering Mechanics (PhD)
Administrative Home Department
Department of Mechanical and Aerospace Engineering
Advisor 1
Fernando Ponta
Committee Member 1
Leonard Bohmann
Committee Member 2
Ana Dyreson
Committee Member 3
Kazuya Tajiri
Abstract
An easily noticed trend in the utility-scale wind turbine industry is that the size of the machines has continued to increase over time. While this may have benefits in terms of increasing the power generation for a single turbine, a major drawback is the rate with which the weight of the turbine blades grow. To ensure these larger machines can be utilized, efforts are being put forth to create lighter blades. This may fix the weight issue, but brings on a new one; these lighter blades can also be more flexible than previously studied ones. It is, therefore, vitally important to understand how these larger and more flexible blades react and oscillate when a gust event occurs, and how these interactions may differ from previously researched smaller-scale turbines. The information presented in this dissertation will discuss three Stages of work designed to elucidate the aero-elasto-inertial behavior of said more flexible blades, based on simulation data generated with the CODEF modeling tool, in combination with a Reduced Order Characterization technique (ROC). The First Stage explored the effects of different construction techniques on the blade dynamic response, studying reductions of the material used for the blade outer shell, as well as for the internal spar cap in box-beam spar style turbine blades. The Second Stage of this work aimed to broaden the scope of the ROC leading to a universal non-dimensional characterization of the turbine's oscillatory response, which could be applied to turbines of any size, operating in any set of wind conditions, as long as they share geometrical and material similarity. This stage culminated in describing a stability map for the rotors oscillatory response, using Tip Speed Ratio values for various wind speeds in the operational regime of the turbine. The Third Stage of this research focused on the analysis of the physical mechanisms behind the rotor's oscillatory response in both the stable and lower unstable regions, and how energy can either be damped or fed into the rotor as an oscillatory system based on Tip Speed Ratio.
Recommended Citation
Yates, North A., "ON THE VIBRATIONAL DYNAMICS OF WIND TURBINE BLADES: THE OSCILLATORY RESPONSE TO GUST PULSES, AND THE PHYSICAL MECHANISMS BEHIND THEM", Open Access Dissertation, Michigan Technological University, 2026.