Abstract: In order to prevent from catastrophic destruction when the iced blade is disturbed by the flow, the dynamic characteristics of the blade with or without icing are analyzed by using ANSYS to model a 46.5 m blade. In specific, first two-order flap-wise and lag-wise modes and first-order torsional mode are calculated, which are under five kinds of working conditions of the blade including ice-free, uniform or non-uniform icing conditions influenced only by ice mass or by mass and its stiffness together. And then they are comparatively modal analyzed to understand how ice mass and stiffness affect dynamic characteristics of the blade through MAC. The results show that ice can significantly increase the mass of blade resulting in reduced natural frequencies of blade, with the first-order flap-wise frequency decreasing by a maximum of 47.79 percent. At the same time, it can also increase the stiffness of blade resulting in the increase of the nature frequencies of blade, with the first-order torsional frequency increasing by a maximum of 39.51 percent. Flap-wise and lag-wise modal shapes of blade are less influenced by ice, but torsional modal shape of blade in 30 m~46.5 m is greatly affected among which it is the first torsional modal shape of blade under uniform icing condition that is influenced more obviously.

Key words: wind turbine blade, ice, finite element, modal analysis