Modeling the fatigue behavior of wind turbine under the extreme fluctuations aerodynamic load impact

In this thesis, we have undertaken a multifaceted approach to enhance the performance of wind turbine blades. Our investigation encompasses both the aerodynamic design of the blades, aimed at increasing power output, and a comprehensive examination of the blade’s structural aspects to address issues about vibration, fatigue, and cracking. Through a thorough analysis of the blade’s structural properties and material characteristics, we have developed strategies to bolster its durability, reliability, and overall efficiency. By optimizing the aerodynamic profile of the blade and tackling potential challenges like vibration, fatigue, and cracking, our thesis has contributed to the advancement of more efficient and sustainable wind turbine blades for renewable energy systems. in our thesis, we laid the foundation by offering a comprehensive literature review on horizontal-axis turbine blades. We introduced the methodology employed in designing small wind turbine blades, incorporating theories from Blade Element Momentum (BEM) and Computational Fluid Dynamics (CFD), illustrating how these methods can be harnessed to analyze wind turbine blades. An in-depth examination was also conducted of blade vibrations, encompassing the determination of natural frequencies and mode shapes to enhance blade performance. By delving into vibration-related concerns, this chapter sought to inform improvements in wind turbine blade design and operation. In our thesis, we also focused on the crucial topic of fatigue. We provided a comprehensive understanding of fatigue, particularly as it pertains to wind turbine blades. We presented advancements in blade design geared towards extending fatigue life and simplified fatigue equations for small wind turbine blades, introducing the Spectral Load Model (SLM) method and utilizing the FAST tool to infer fatigue. we conducted a detailed analysis of cracks in wind turbine blades resulting from prolonged operation under varying loads and weather conditions, we introduced the Extended Finite Element Method (XFEM), a specialized technique for studying cracks, to gain insights into the timing and extent of crack initiation and propagation within the blade structure. Finally, we synthesized the results obtained from the analyses discussed in our thesis. We aimed to consolidate these findings into a coherent and comprehensible framework, enhancing their overall clarity and significance. This integrated approach allowed us to contribute valuable insights into the improvement of wind turbine blade performance, thereby advancing the field of renewable energy.