Nonlinear Deformation Of Thin-Walled Composite Box Beams With SMA Fibers

As a kind of clean and renewable energy, wind power has been paid more and more attention. Wind power technology is mature and can be developed on a large scale, wind power has a broad commercial development prospects. The key of wind turbines design is the structural characteristics, dynamics characteristics, and stability problems of the wind machine.The wind turbine blade will be considered as a slender thin-walled beam in this paper. The objective of this paper is to present a general geometrically nonlinear analysis model for investigating the static deformation behavior of thin-walled composite box beams. Then based on the nonlinear model, the influence of deformation characteristics of thin-walled beam with integrated shape memory alloy (SMA) fibers inspired by temperature is studied.For the static deformation of thin-walled beams, combined with laminated composite macroscopic mechanical, the two-dimensional stiffness matrix with arbitrary section of thin-walled beam is derived by the variational asymptotic method (VAM) firstly. Then the geometrically nonlinear equations of the deformation are given, the nonlinear equilibrium equations of the thin-walled beams are derived using the variational principle. By employing the Galerkin's method, nonlinear algebraic equations is derived and then solved by means of an incremental Newton-Raphson method finally. The effect of nonlinear terms on deformation with variable load and fiber orientation is discussed by numerical calculation of two typical section thin-walled beams.And for the active deformation of thin-walled laminated beams with integrated SMA fibers, the analytical expressions of the actuation components for the active beam are derived based on the Tanaka's SMA stress-strain relations and Lin-Rogers's linear phase transformation kinetics for SMA fibers. Then those terms are added to the linear part of the generalized force, and the corresponding equilibrium equations are derived. Numerical results are obtained for two typical section box beams under vertical load to investigate the influence of geometric nonlinearity and address the effects of the incentive temperature, volume of SMA and fiber orientation on the deformation response.