Modal analysis of cracked wind turbines using the finite element method

In this paper, we develop a Finite Element Model (FEM) of a large-scale Horizontal Axis Wind Turbine (HAWT) with flexible tower and blades using ABAQUS. This research has been initiated for the need to validate a mathematical model of the HAWT that was recently published in the literature. In addition, the developed FEM serves for better understanding of the effects of cracks with different shapes and orientations on the dynamic behaviors of the wind turbine. We perform a modal analysis to determine the first two sets of four natural frequencies and corresponding mode shapes. The influence of crack position, size, shape and number on the eigenstructure of the wind turbine is thoroughly investigated using the FEM. The current study will enable the authors to conduct a future investigation on the influence of structural damage on the dynamic response of the HAWT. In particular, future research will focus on determining a set of parameters and/or dynamic variables that are sensitive to crack development. This research is highly valuable for damage detection and health monitoring processes.