Study On D₁₅ Model Macro Fiber Composite And Its Vibration Control Application

Macro fiber composite?MFC? is a sandwich structure functional composite material in which consisting of piezoelectric fibers,epoxy resin and interdigitated electrode,which is widely used in the field of vibration control due to its excellent piezoelectricity and good flexibility.There are many MFCs in the field of vibration control,which are d₃₁ and d₃₃ mode both control the structural vibration through the telescopic mode.In recent years,a d₁₅ mode MFC has received attention due to the higher d₁₅ which can produce large bending deformation.This paper development a design and preparation method of d₁₅ MFC?SMFC?and studied its electric properties,and evaluates the feasibility of SMFC for active vibration control of cantilever beam structure.The specific research work and conclusion are as follows:The influence of the electrode structure and the thickness of the composite fiber layer on the electric field distribution along the fiber in the MFC were analyzed by the finite element method.In was found that under the premise of ensuring the electric field and other structural parameters,increasing of the electrode spacing and decreasing of its width and the thickness of the composite fiber layer are beneficial to extend the active electric zone in the fiber and enhanced the piezoelectric properties of MFC.In addition,the electric field in the fiber near the edge of the electrode increases significantly with the increase of the electrode spacing,even exceeding the withstand voltage of the composite,causing dielectric breakdown.According to the optimized structural parameters,the SMFC which polarized along the thickness direction of fiber was prepared by the cutting-filling method.The effect of piezoelectric function on SMFC performance was studied.It was found that the bending deformation of PZT-Mn based SMFC was higher than that of PZT-5based SMFC under the same electric field.The effects of electric field and ambient temperature on the performance of PZT-Mn based SMFC are studied.The results show that when the driving electric field was lower?0.5 kV/mm?,the SMFC of the hysteresis loop was almost linearly;when it reached 2.0 kV/mm,the hysteresis loop is“waist”,the axial strain was 3430??,the equivalent shear piezoelectric coefficient d^*₁₅ is 1715 pm/V,and the bending deformation was 0.36 mm,which indicates that SMFC has potential application in bending vibration control.The remanent polarization and bending deformation of SMFC increased with the increase of temperature;continue to raise the temperature,the hysteresis loop appears to be yield,the leakage current increases,the bending deformation decreases,and the fiber and electrode are fall off,which means that the SMFC has better driving performance at higher temperature without causing structural damage and depolarization due to external temperature.The fatigue characteristics of the ferroelectric and actuation properties of the SMFC were studied.The results show that the remanent polarization of SMFC tends to be stable with the increase of electric field loading period when it is lower than the coercive field,and gradually decreases when it is higher than the coercive field.The cantilever beam can still produce stable bending deformation after10³ cycles under the driving electric field below the coercive field,which indicates that the SMFC has excellent properties stability.The vibration control experimental platform was designed.The SMFC was used as the vibration suppression component to control the vibration of cantilever beam.The results show that the SMFC can effectively control the vibration of cantilever beam regardless its vibration at resonant frequency or not.When the SMFC is subjected to the same frequency and anti-phase excitation of the SMFC at the resonant frequency of the cantilever beam,the amplitude of the cantilever beam is attenuated by 53%.The SMFC exhibits minimum amplitude attenuation of the cantilever beam,then increases and tends to be stable,and the time during which the cantilever beam amplitude decays to minimum is independent of the driving electric field.Therefore,applying a discontinuous alternating electric field to the SMFC can stabilize the cantilever beam amplitude to a lower state,thereby achieving a more effective control of the vibration.