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    Effects of Atmospheric Icing on Performance of Controlled Wind Turbine
    (Institute of Physics, 2022) Sahin, M.; Farsadi, T.
    Icing deteriorates the performance of wind turbine rotors by changing the blade airfoils' shapes. It decreases the lift, increases the drag, and subsequently causes power production losses and load increase on turbines' structures. In the present study, the effects of atmospheric icing on the performance of a controlled large-scale wind turbine is estimated through simulations. To achieve the target, the MS (Mustafa Sahin) Bladed Wind Turbine Simulation Model is used for the analyses of the National Renewable Energy Laboratory (NREL) 5 MW turbine with and without iced blades. Icing modeling is realized based on its main characteristics and its effects on blade aerodynamics. Turbine performance estimations are carried out at various uniform wind speeds between cut-in and cut-out wind speeds and are presented in terms of various turbine parameters such as power, thrust force, blade pitch angle, and rotor speed. Simulation evaluations show that even a light ice accretion along the blades varies the turbine characteristics and dynamics, changes the cut-in and rated wind speeds, and affects the aforementioned turbine parameters differently in the below and above rated regions. © Published under licence by IOP Publishing Ltd.
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    Frequency study of functionally graded multilayer graphene platelet-reinforced polymer cylindrical panels
    (Polish Acad Sciences Inst Fundamental Technological Research, 2021) Farsadi, T.; Asadi, D.; Kurtaran, H.
    IN THIS STUDY, NONLINEAR FUNDAMENTAL NATURAL FREQUENCIES of Functionally Graded (FG) multilayer Graphene Platelet-reinforced Polymer Composite (GPL-RPC) curved cylindrical panels are studied. It is considered that the Graphene Platelet (GPL) nanofillers are distributed in the matrix either uniformly or non uniformly along the thickness direction. Four GPL distribution patterns namely, UD, FG-O, FG-X, and FG-A are considered. The effective material properties of GPL-RPC layers are obtained via the modified Halpin-Tsai micromechanics model and the rule of the mixture. A nonlinear structural model is utilized based on the virtual work principle. Green's nonlinear kinematic strain relations are used to account for the geometric nonlinearities and the First-order Shear Deformation Theory (FSDT) is adopted to generalize the formulation for the case of moderately thick cylindrical panels including transverse shear deformations. The Generalized Differential Quadrature (GDQ) method of solution is employed to solve the nonlinear governing equations of motion. The present study aims to study the effect of GPL weight fraction for the proposed distribution patterns on the nonlinear fundamental frequency of functionally graded GPL-RPC cylindrical panels with different boundary conditions.
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    Vibration analysis of sandwich cylindrical shells made of graphene platelet polymer-viscoelastic-ceramic/metal FG layers
    (Iop Publishing Ltd, 2023) Permoon, M. R.; Farsadi, T.; Askarian, A. R.
    In this paper, natural frequencies and loss factors of cylindrical sandwich shells composed of the viscoelastic core layer, surrounded by functionally graded graphene-platelet reinforced polymer composite (FG-GPLRPC) and ceramic/metal (FG-ceramic/metal) are investigated. The viscoelastic layer is modeled via the fourth parameter fractional viscoelastic pattern, and the functionally graded ceramic/metal layer is theoretically modeled using a power-law function. The uniform, symmetric and un-symmetric patterns are considered for simulating the graphene platelet (GPL) nanofillers distributions along with the thickness direction. The classical shell theory is used for functionally graded layers and properties of the effective materials of GPLRPC multilayers are determined by using a modified Halpin-Tsai micromechanics model and the rule of mixture. The governing equations of motion are extracted by applying the Lagrange equation and the Rayleigh-Ritz method. The determinant of the coefficient matrix of the characteristic equation is calculated, and the natural frequencies and loss factors of the system are extracted. A study of the interactions of materials and geometrical factors such as the ratio of radius to length, the properties of functionally graded materials, and GPL weight fractions for patterns of proposed distributions are presented and some conclusions have been formed.