The Propagation Of Gap Wave In Piezoelectric Phononic Crystal Structures

Phononic crystal is a composite material with artificial periodic structures.In recent years,with the increasing application of piezoelectric materials,piezomagnetic materials and other functional materials in the field of phononic crystals.The application of the phononic crystal has been greatly expanded,such as resonators,filters,sensors,microfluidic gymnastics control and other fields can use the unique physical characteristics of the phononic crystal to achieve performance improvement.However,with the development of technology,the frequency of the device increases gradually(up to several GHz),and the structure of phononic crystal becomes more and more complex.The multilayer structure and the layered structure with gaps are gradually favored by scholars.Therefore,we consider whether the existence of gaps in the piezoelectric and piezomagnetic phononic crystal structures will affect the performance of the structure.On the other hand,find whether these gaps can be used to control the wave propagation in the phononic crystal.Based on this,this thesis mainly studies the following aspects:(1)The propagation of gap waves in a structure with a gap in the semi-infinite piezoelectric phononic crystal is studied.The plane wave expansion method and the finite element method are used to calculate the band structure of the gap wave.The influence of the filling rate of phononic crystal on the band structure was investigated.Besides,compared to the absence of the gap,the effects of the gap geometry,and the properties of the filler in the gap on the gap wave propagation are calculated.(2)The gap wave propagation in a piezoelectric phononic crystal with a homogeneous piezoelectric layer is studied.The plane wave expansion method and the finite element method were used to calculate the effect of the phononic crystal matrix filling rate on gap wave propagation.Considering the electrical short and electrical open condition of the piezoelectric layer surface,the influence of the gap wave propagation by the thickness of the layer,the width of the gap,and the properties of the gap dielectric properties is calculated.(3)The gap wave in the structure of phononic crystal with the magneto-electro-elastic material layer is studied.The plane wave expansion method and the finite element method are used to calculate the effect of different ratios of the mixed magnetoelectric material layer on the gap wave propagation.Besides,consider the influence of the change in the gap geometry and the medium properties in the gap on the band structure of the gap wave in the piezoelectric phononic crystal with magnetoelectric layer structure.(4)The gap wave propagation in the piezoelectric material layer and piezoelectric/piezomagnetic phononic crystal structure is studied.The finite element method is used to calculate the influence of the filling ratio of piezoelectric/piezomagnetic phononic crystals on the gap wave propagation.The influence of the gap geometry and the change of the dielectric properties in the gap on the band structure of the gap wave is considered.The sensitivity of the band gap of the phononic crystal to the change of the dielectric properties in the gap is investigated.