Passive Control Of Vibration Of Large Wind Turbine Composite Blade Based On Shape Memory Alloy

The blade is the most basic and critical component of a wind turbine and is the decisive factor for the normal and stable operation of the unit.With the large-scale development of modern wind turbines,the increase of blade length leads to the increase of wind turbine radius and the increase of blade flexibility.The blade is subjected to wind load action to produce vibration,if the vibration is not effectively controlled,it will cause huge economic losses.In the research of wind turbine blade vibration control,smart materials have received attention.Among them,the superelastic properties of shape memory alloy(SMA)materials are widely used and studied in the passive vibration reduction design of structures.To study the feasibility of using the pseudo-elastic energy dissipation property of SMA for passive control of wind turbine blade vibration,this paper pastes the superelastic SMA sheet onto the surface of the composite blade and analyzes the vibration suppression effect of superelastic SMA on the blade.The research contents and conclusions of this paper are as follows.(1)The Auricchio intrinsic structure model describing the phase transformation process of SMA is introduced.Based on the Auricchio model of the shape memory alloy and the finite element analysis software ANSYS Workbench,the pseudo-elastic properties of SMA are studied in three cases.Firstly,the pseudo-elastic energy dissipation characteristics of the SMA bar during the tensile cycle of loading and unloading are simulated,and the influence of the strain amplitude on the single-turn energy dissipation,equivalent stiffness,and equivalent damping ratio of the pseudoelastic SMA bar is analyzed.Secondly,the mechanical behaviors of SMA vertical correction curves during the operation were simulated and calculated,and it was found that the whole deformation process of SMA vertical curves showed a hysteresis loop effect,and the SMA vertical curves rebound force and moment increased with the increase of asymmetry degree.Finally,the static/dynamic response of the SMA composite cantilever beam under transverse load was studied,and it was found that the deformation of the SMA composite beam also showed hysteresis effect due to the pseudo-elastic energy dissipation property of SMA,and the energy dissipation capacity of SMA composite beam gradually increased with the increase of external load.After adding SMA,the response value of the free end of the composite cantilever beam decreases.(2)The actual wind turbine blade is a multi-closed hollow airfoil structure.In this paper,the wind turbine blade is first simplified into a triple-closed box beam structure,and a triple-closed SMA hybrid composite box structure beam is built based on ANSYS software,and the variation of the first two orders of the intrinsic frequency with the layup angle under the CUS configuration is compared with the literature results.The accuracy of the model was verified.On this basis,the modal and static response analysis of the model was carried out to explore the effects of different stiffness configurations,composite lay-up methods,volume content of single-layer SMA,lay-up angle,and beam dimensions on its modal and static response.(3)The aerodynamic design of the 8MW wind turbine blade was carried out based on the Wilson theory model,the geometric parameters of the blade were defined,the blade airfoil shape was selected and the coordinate points were derived using Profili software,the solution of the spatial coordinates of the blade section was completed using Excel software,and the modeling of the wind turbine blade shell model was completed using the modeling software Solidworks;to meet the blade strength and stiffness,the glass fiber/epoxy resin material and carbon fiber material/epoxy resin material are selected for the blade lay-up,and the lay-up scheme of the blade is given,and the local refinement of the blade is carried out;the established wind turbine blade model is compared with the literature for verification,and the accuracy of the model is verified.(4)The types of loads on the wind turbine blade are analyzed,which include aerodynamic loads,gravity loads,and centrifugal loads.The model of SMA composite large wind turbine blade was established by filling the superelastic SMA sheet to the surface of the main beam of the blade.The load was simplified to a concentrated load,and the displacement response analysis and stress response analysis were performed on the wind turbine blade.The study shows that: a closed hysteresis loop is formed between the stress-strain of the SMA layer,and the SMA undergoes a martensitic positive phase change and reverse-phase change respectively under the transverse load;the blade tip displacement decreases due to the strengthening of SMA,and the maximum decrease is25%.With the increase of loading time,the deflection produced by the leaf tip is also greater,and the pseudo-elastic suppression effect of SMA is more obvious;due to the effect of SMA,the whole wind turbine blade also shows the pseudo-elastic energy dissipation characteristics,which can dissipate part of the energy in the process of loading and unloading;with the increase of transverse load,the area of hysteresis ring also increases,and the energy dissipated is also more.Under the action of lower load,the blade presents lower strain,the hysteresis loop formed is smaller,and the energy dissipated is lower.(5)The harmonic response analysis of the SMA wind turbine composite blade was carried out based on the modal superposition method,and the modal results were frequency-checked to verify the inherent frequency of the model.The amplitudefrequency characteristic curves in the waving and pendulum vibration directions were obtained,and the study showed that the presence of SMA shifts the inherent frequency of the blade to a higher frequency.The amplitude corresponding to each order of mode is significantly reduced,and the pattern is similar in the waving and pendulum vibration directions.The response peaks when the excitation force frequency is close to the blade's intrinsic frequency,and in other frequency bands,the response is smaller.Among them,the maximum amplitude of 3.25 m appears at the frequency 0.16 Hz,and the amplitude is reduced by 11.87% due to the presence of SMA.(6)The stochastic vibration of SMA composite wind turbine blades was simulated using the finite element method.It is shown that in the range of vibration energy bandwidth,the energy of vibration gradually decreases with the increase of frequency.The energy of vibration is mainly concentrated in the range of 0.5 Hz to 2.4 Hz.At the same frequency,the smaller the response value of vibration energy of wind turbine blade strengthened by SMA.At the same time,it can be found that the vibration response maximum moves to higher frequencies,which is consistent with the results of harmonic response analysis and has the same pattern in the pendulum vibration direction.The vibration damping effect of SMA on the wind turbine blade is further verified by the cloud map of blade displacement distribution.For the three different lay-up schemes of SMA,the displacement response value of SMA is lower for the full lay-up of the main beam of the blade.