Structural analysis and optimization of wind turbine blade for offshore applications

This master’s thesis work stems from a combined interest in complex structures and renewable energy production. In the context of the energy transition, the need for a shift to cleaner energy sources is evident, and countries all over the world are facing this challenge along with its related issues. Wind energy is a key player in this transition and is expected to be one of the largest components of the energy mix in the coming decades. Additionally, offshore wind energy is of significant interest to researchers and investors due to its clear advantages over onshore wind energy, primarily greater wind availability and reduced impact on land environments. With this premise, this thesis focuses on the structural aspects of offshore wind turbine blades. The thesis begins with an introduction that contextualizes the problem by presenting the current state of wind energy in terms of installed gigawatts and highlighting the countries most involved in the development of this technology. Following this, an overview of offshore wind energy is provided, outlining its advantages and disadvantages compared to onshore wind energy. After the introduction, key theoretical concepts are discussed to understand the aerodynamic parameters involved in blade design that most significantly affect turbine performance. Next, a description of the loads acting on the turbine rotor is presented, followed by a review of the state-of-the-art in wind turbine blade structures. This section explains the load distribution among various structural components, with a focus on composite materials that have replaced metals, following trends in the aerospace industry. A simplified finite element model of a reference 15 MW wind turbine blade is created using ANSYS Mechanical. The model is automated with a Python script using PyMechanical. With the model established, several analyses are conducted to verify both the model and the structural properties of the blade. In the end, using the introduced FEM model, an optimization process is performed on the blade with the objective of reducing its cost by minimizing material usage while respecting certain structural constraints.