The natural modes as well as the aeroelastic stability of a plate with attached piezoelectric material in response to a change in electric potential are studied. A finite element model is developed based on the classical lamented plate theory. The piezoelectric stiffening effect is obtained using the concept of a change in geometric stiffness. Three piezoelectric configurations are considered in the present work: (1) with the piezoelectric actuators covering the whole plate, (2) with the piezoelectric actuators covering a portion of the plate near the clamped support, and (3) with the piezoelectric actuators covering a portion of the plate near the free end. In all the three cases, the piezoelectric sheets cover the plate on both sides. The second configuration is effective in stiffening the plate, while the first and third configurations are effective in buckling the plate. We also find the piezoelectric force has a significant effect on wing natural modes and aeroelastic stability. An increase in negative applied voltage can increase the aeroelastic stability, while increasing the positive voltage can decrease the plate stability. The piezoelectric effect on the plate torsional modes is more significant than its effect on its bending modes. The selection of the piezoelectric material configuration as well as the applied voltage is important for stiffening or weakening a plate.
With the negative impact of conventional energy resources that have been used worldwide, there is a demand for using other resources such as wind energy. Tons of researches have been applied around the globe on the process of designing and manufacturing wind energy conversion systems. In the present chapter, we are concentrating on wind turbine blades' structural design process. The structural design of a wind turbine blade includes defining the wind turbine loads, selecting a suitable material, creating a structural model, and solving the model using the finite element method. This process will be repeated several times until a final design is achieved. The present chapter includes a discussion on the finite element method and wind turbine aeroelasticity.
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