Active Control Of Wave Propagation In Soft Phononic Crystals

Phononic crystals are synthetic periodic functional materials.Similar to an atomic crystal having an electronic energy band structure,the phononic crystal can block sound waves or elastic waves from passing at a specific frequency.The unique bandgap characteristics of phononic crystals make them widely used in vibration reduction and noise reduction,acoustic wave control and waveguides.With the development of phononic crystals,people not only hope to produce phononic crystals that can achieve specific functions,but also hope that they can flexibly change the structure and performance of phononic crystals in practical applications,so that phononic crystals can have different excitations.Respond to achieve active regulation of acoustic or elastic waves.In this paper,starting from the nonlinear continuum theory,the propagation of wave in the dielectric hyperelastic materials and superelastic material phononic crystals is studied with numerical methods.Two kinds of soft material phononic crystals are studied in the external electric field.Under the action of the force-bias field,the structural bandgap and the transmission characteristics of the change,so as to provide some theoretical basis for the innovative design of the phononic crystal can be regulated.The main research content is as follows:1)Based on the continuous dielectric theory of non-linear dielectric materials proposed by Dorfmann and Ogden,a one-dimensional incremental constitutive equation and equilibrium equation of incompressible dielectric elastomer material under the action of a preset electric field are derived based on the Gent energy model.The anti-plane shear fluctuation increment equation was used to study the influence of the incident wave angle,the external electric field,and the ratio of the bulk to the dielectric material on the propagation characteristics of the anti-plane shear wave of the dielectric hyperelastic phononic crystal.2)Based on the in-plane force electro-mechanical coupling two-dimensional incremental equation of motion,according to the boundary conditions of the force field and the electric field on the surface of the structure,the attenuation coefficient and the wave velocity of the surface wave along the depth direction of the dielectric elastomer material are first calculated,and the external power is discussed.The influence of the partial field on the surface wave propagation and the conditions of existence,based on the continuity conditions,gives the expressions of the structure transfer matrix and localization factors,and analyzes the surface wave propagation and localization behavior of different external bias field parameters impact.3)Using three-dimensional layered phononic crystals composed of three compressible super-elastic materials as the research object,nonlinear finite deformation theory is used to calculate the three kinds of three component material parameters under different force-bias fields,and the geometric dimensions Then,through the finite element software Comsol modeling,the longitudinal propagation of the small incremental field in the structure is studied.The influence of the prestressed bias field on the distribution of the structural bandgap is analyzed,and the force field is theoretically realized for the one-dimensional three-component element.Active regulation of longitudinal wave propagation in superelastic phononic crystals.