Flexoelectric Vibration Control And Energy Harvesting Of Smart Structures

Smart structures and structronic system have the advantage of light weight,fast response and high flexibility and so on,which can be used in structure sensing,vibration control,noise control and stability control.in the field of aerospace,mechanical engineering,biological and medical,ect..Since the flexoelectric dielectric doesn't need complicated pre-poling and has no aging effect,which is simple and convenient in application,the flexoelectric smart structronic system is promising for sensing and vibration control in engineering.This study establishes an electromechanical coupling dynamic model based on the thick double-curvature shell.The shear effect and rotatory inertia effect are considered,and the von Karman geometrical nonlinearity induced by the large deformation is also involved.The dynamic equations of the thick flexoelectric shell based on the converse flexoelectric effect and the modal response for each mode are derived.The theory based on the thick flexoelectric double-curvature shell can be applied to thin flexoelectric double-curvature shell with/without von Karman geometrical nonlinearity.Based on the Lame parameters and curvature radii of the specified structure,one can simplify the shell theory to account for many linear/nonlinear shell(e.g.,cylindrical,conical,spherical,etc.)and non-shell(beam,plate,ring,arch,etc.)structures.The key factor for flexoelectric vibration control is to establish inhomogeneous electric field,i.e.,the electric field gradient.Thus,this study develops the electric field gradient by using the(Atomic Force Microscope)AFM probe,conductive line and the metal-core flexoelectric fiber,which can be used to control the structure.Based on the AFM probe excitation,vibration control of the flexoelectric cantilever beam is established and tip displacement induced by the flexoelectric effect is evaluated.In order to validate the flexoelectric actuation effect,flexoelectric actuation experiments when actuator locates at different locations are conducted,and the experiment results are compared with the theoretical prediction.Different parameters of the model are discussed to optimize the control effect.Due to the electric field gradient induced by the conductive line,vibration control of the rectangular plate which is two edges simple-supported and two edges free are discussed.Displacement of different modes induced by the flexoelectric effect is evaluated and the different parameters are optimized.Based on the metal-core flexoelectric fiber,electromechanical coupling equation of the fiber is established,and vibration control of the cantilever beam used by the metal-core flexoelectric fiber is discussed.Based on the direct flexoelectric effect,flexoelectric energy harvester based on the double-curvature shell is developed.Electromechanical coupling and the voltage and the power output of the double-curvature shell are derived.Based on the Lame parameters and curvature radii of the specified structure,the generic flexoelectric energy harvester can be applied to flexoelectric cylindrical shell,ring and beam energy harvester.Based on the ring energy harvester,different parameters are discussed to optimize the power output.Finally,in order to discuss the application of the flexoelectric effect in the engineering,flexoelectric distributed sensing and actuation of the toroidal shell is discussed.Different curvature angle and components effect on sensing and vibration control for each mode are evaluated.