Adavances in composite wind turbine blades: A comparative study

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CHAPTER V, Fatigue Model:
5.1, Overview:
Even though composite materials are designated as being fatigue-insensitive, especially when compared to metallic ones, they also suffer from fatigue loads. The use of composite materials in a wide range of applications obliged researchers to consider fatigue when investigating a composite material and engineers to realize that fatigue is an important parameter that must be considered in calculations during design processes, even for structures where fatigue was not traditionally considered an issue. Although composites were initially used as replacements for conventional materials such as steel, aluminum or wood, and later as advanced materials allowing engineers to adopt a different approach to design problems, the fatigue behavior of composite materials is different from that of metallic materials. Therefore, the already developed and validated methods for the fatigue life modeling and prediction of conventional materials cannot be directly applied to composite materials.
Mathematical models have been developed to describe fatigue damage analytically and eventually predict the fatigue lifetime of FRP composite materials. The ideal fatigue theory is described by Sendeckyj in 27 as one based on a damage metric hat accurately models the experimentally observed damage accumulation process, considers all pertinent material, test and environmental variables, correlates the data for a large class of materials, permits the accurate prediction of laminate fatigue behavior from lamina fatigue data, is readily extendable to two-stage and spectrum fatigue loading and takes data scatter into account. These requirements cannot be met simultaneously for many reasons and theoretical models that address only some of them have been introduced. For predicting the fatigue life of structural components made of composites, at least two alternative design concepts could be used: the damage-tolerant (or fail-safe) and the

A PhD student in engineering at the University of Quebec at Chicoutimi (UQAC). I hold a BS and a MS in Mechanical Engineering from the Lebanese University, Beirut, Lebanon. Currently preparing my PhD thesis on Optimization of composite structures of wind turbine blades . Experience, skills and knowledge in the fields of aerodynamics, composites and optimization and its applications in Wind Energy. My master thesis was a comparative study of static and fatigue behaviours for various composite orthotropic properties for a wind turbine using a coupled FEM-BEM method under the supervision of Dean Dr Rafic Younes of the Faculty of Engineering at the Lebanese University. Some of my projects and work include preliminary study of the influence of air pollution on meteorology , Hybrid System Photovoltaic-Wind , yaw control for a wind turbine , design and prototype of a sensor for wind direction using thermocouples and preliminary site study for the installation of 100 and 150 KW wind turbines in the Bekaa region.