Coupled bending and torsional vibration characteristics analysis of inhomogeneous wind turbine tower with variable cross section under elastic constraint

Abstract

The separation of cross section’ mass center from its centroid will lead to coupled bending and torsional vibration of the wind turbine tower (Referred to as tower). Three governing differential equations of vibration of the tower with inhomogeneous material and variable cross section are formulated based on D'Alembert's principle and Euler-Bernoulli beam theory. Considering the installation and operation factors of the wind turbine, the dimensionless natural frequencies and mode shapes of the tower under multiple constraint conditions are obtained by the differential quadrature method. Compared with those available in the literature, numerical results demonstrate the accuracy and validity of the proposed method. A series of parametric study is accomplished to reveal the influence of the foundation stiffness, wall thickness, eccentricity, and the ratio of the inner diameter of the top and bottom cross section of tower on the vibration characteristics of tower. The frequencies veering for the mode of tower is discussed. These numerical results have guiding significance for the design of tower.