Fabrication Of Composite Piezoelectric Polymer P(VDF-TrFE) And Its Performance Testing For Flexible Ultrasonic Transducers

Structural health monitoring technology is of great significance in ensuring the safety of key structural structures,reducing maintenance costs,and extending the service life of structures.Sensors are the key technology for structural health monitoring.Existing rigid sensors are difficult to be fully applied in actual engineering structures due to the poor reliability,heavy weight,and large volume of the test results caused by the adhesive coupling to the structure to be measured.Flexible sensing technology is an important direction to solve existing structural health monitoring problems.The new flexible sensing technology uses flexible materials such as polymers,combined with a new manufacturing process,to directly prepare the entire sensing network on the structure to be tested,and flexibly arrange it in complex profiles,with high detection sensitivity,light weight,good flexibility,and Design and other advantages.In this paper,we will develop a high-performance flexible piezoelectric film material based on copolymer polyvinylidene fluoride-trifluoroethylene(PVDF-TrFE)for mainstream structural health monitoring methods based on ultrasound technology,and develop a flexible ultrasonic sensor unit based on this.Complete various forms of active and passive monitoring,provide key technical support for the application of structural health monitoring technology in aerospace,rail transit and other engineering structures,and provide reliable,easy-to-use,and applicable flexible composite piezoelectric film sensors.Helpful try With the orderly and vigorous development of aviation and aerospace industries,structural health monitoring(SHM)technology has become an indispensable part of the life cycle monitoring of aerospace structures.Compared with the traditional piezoelectric single crystal and piezoelectric ceramics,the P(VDF-TrFE)flexible ultrasonic transducer provides a feasible method for practical SHM applicationsIn this paper,P(VDF-TrFE)was doped with ZnO to improve the ?-phase content of the film and further increase the piezoelectric coefficient to prepare a flexible ultrasonic transducer with reliable performance.By doping ZnO nanoparticles with different mass fractions and cooperating with n-propyl amine(PA)and 1H,1H,2H,2H perfluorooctyltrimethoxysilane(PFOES)to modify the surface of them,the dispersion of ZnO was improved.Based on the flexible sensor rapid preparation platform,the annealing temperature for P(VDF-TrFE)to obtain high crystallinity was verified.Based on this,the preparation conditions of P(VDF-TrFE)/ZnO were explored.The annealing temperature was determined to be 135? and the annealing time was 2h.Anneal at room temperature and corona polarization at 70?.Under this preparation condition,the crystallinity of ? phase is greatly improved by the piezoelectricity of ZnO nanoparticles and the role of nucleating agent.Compared with d33=20.5pC/N of P(VDF-TrFE),the d33 of P(VDF-TrFE)/ZnO with a doping concentration of 10wt%can reach 28.9pC/N,but as the concentration of ZnO increases,agglomeration causes The ?-phase crystallinity decreases,resulting in a decrease in piezoelectric performanceWith respect to the receiving and transmitting aspects of flexible ultrasonic sensors made from P(VDF-TrFE)/ZnO piezoelectric composites,this paper tests their ability to receive voltage response and their ultrasonic emission performance to verify the sensor's ultrasonic nondestructive testing and structural health monitoring Applications.In terms of receiving signals,in the small ball impact experiment,the P(VDF-TrFE)/ZnO voltage response of 10wt%can reach 1.81V,and it can show good linearity under different impact energy.The sensor fabricated on the 6061 aluminum plate can have a good frequency response between 50kHz and 1MHzThe comb-shaped electrode was designed to excite 800kHz ultrasonic waves and obtain the time domain signals of the ultrasonic signals.The conclusion after sampling in the full time domain is that the voltage response of 10wt%modified P(VDF-TrFE)/ZnO is 57.6%higher than that of pure P(VDF-TrFE).The amplitude of the FFT in the frequency domain shows that 10wt%of the modified P(VDF-TrFE)/ZnO has 43%and 46%enhancement in the amplitude of the AO and SO wave signals compared to pure P(VDF-TrFE).