Nonlinear Finite Element Analysis Of Embedded Pseudo Elastic Shape Memory Alloy Composite Beams

Wind turbine blade is one of the key components for wind turbine to capture wind energy.As a slender flexible body structure,blades are easily vibrated under complex external loads.With the continuous development of technology,the blade size continue to increase,and the blade structure tends to be more flexible.Geometric linear analysis of blades can not meet the needs of actual working conditions.Therefore,the geometric nonlinear finite element analysis of blades is of great value to the study of blade vibration of wind turbines.Because of its unique shape memory effect and pseudo-elastic effect,shape memory alloy(SMA)has been widely studied and developed in the aspect of structural vibration control.In order to study the vibration suppression effect of SMA on the blade of the wind turbine under geometric nonlinear conditions,this paper w based on the geometric nonlinearity based on the equivalent cross section and variable cross-section laminated beam embedded in the pseudo elastic SMA composite.It is hoped that it will provide a valuable theoretical basis for vibration control and blade life extension in actual working conditions.The main work of this paper is as follows:Firstly,based on the basic theory of composite mechanics,geometrical nonlinear analysis theory,nonlinear finite element analysis and phase transition characteristics of SMA,the nonlinear static equilibrium equations of composite composite beams with embedded SMA fibers are established.The nonlinear static simulation of the embedded pseudo elastic composite solid beam is carried out: the tensile loading and unloading simulation of SMA fiber composite rod is carried out.The relation curve of load and deformation and corresponding stress strain curve under the action of tensile load are obtained,which lays a foundation for the future consideration of the centrifugal force load.ANSYS and MATLAB are used to simulate the pseudo elastic energy dissipation capacity of the SMA fiber composite beam under the geometric nonlinear condition.The accuracy of the MATLAB program is verified,which provides a reliable guarantee for the subsequent use of MATLAB program to analyze the dynamic response of the MATLAB program.Secondly,the influence of volume content,installation location and temperature on the dynamic response of embedded pseudo elastic SMA fiber composite beam is analyzed by MATLAB software.The study found that: the more the volume of SMA fiber is,the smaller the area of the hysteresis loop is,the energy dissipation capacity of SMA is reduced,but its damping capacity increases with the increase of stiffness,and the deflection of the free end is reduced;The farther the distance between the SMA fiber composite layer and the middle surface of the composite beam is,the more obvious the vibration suppression effect for the laminated beam is,and the larger the area of hysteresis loop formed by stress and strain,the greater the energy dissipation capacity;The deflection of the free end of the beam will decrease with the increase of the working temperature,and the linear elastic deformation phase of the SMA fiber is extended,and the stiffness also increases,and its vibration suppression ability is enhanced.However,due to the decrease of the hysteresis area formed by the stress and strain at high temperature,the pseudo elastic energy dissipation capacity of the SMA fiber decreases with the increase of temperature.The influence of above parameters on the pseudo elastic energy dissipation and vibration suppression of SMA fiber composite beams is determined.Subsequently,the dynamic response of SMA fiber composite beam under two kinds of geometric nonlinearity and geometric linearity under transverse dynamic loading is compared and analyzed.It is found that: The deflection of the free end of the beam is obviously lower when the geometric nonlinear analysis is more linear,so the anti vibration ability of the SMA fiber composite layer is stronger than that in the linear analysis.The lag ring area formed by the stress strain relationship of the SMA fiber composite layer decreases as compared with the linear analysis,so the pseudo elastic energy dissipation capacity is weaker than that in the linear analysis.Finally,in order to be closer to the actual work situation,the blade of the wind turbine is simplified as a variable cross section composite hollow laminated beam,and the dynamic response of the blade under the wind load is studied.The influence of structural damping and strain amplitude on the dynamic response of beams is analyzed.It is found that: Structural damping can enhance the vibration suppression effect of SMA fiber composite layer on beams.At the same time,with the increase of strain amplitude,the free end displacement of beams decreases significantly under the same load.And the stress and strain curves of the SMA fiber composite layer move to the right,the hysteresis loop becomes wider,the area of the hysteresis loop increases,and the pseudo elastic energy dissipation capacity of the SMA fiber is obviously enhanced.