Study On Elastic Waves Propagation In Piezoelectric And Piezoelectric Semiconductor Layer Structures

Piezoelectric materials have been widely applied in the smart devices and structures due to their force-electric coupling characteristics,there are the piezoelectric theory with flexoelectric effect,the piezoelectric semiconductor theory and porous piezoelectric theory apart from the classicl piezoelectric theory.These complex piezoelectric theories are more suitable for describing the part mechanics behaviors of smart devices and structures.In this paper,we mainly consider the influences of the magneto-electric-elastic functionally graded interface interlayer in two piezoelectric and piezomagnetic half-spaces and the flexoelectric effect,semiconductor effect and porous effect in piezoelectric material on the reflection and transmission characteristics of elastic waves.The following contents and the innovative conclusions are included:(1).It is investigated that the influences of the magneto-electric-elastic functionally graded interface interlayer in two piezoelectric and piezomagnetic half-spaces on the reflection and transmission characteristics of elastic waves,we establish the state transfer differential equations of the functionally graded interlayer by the reduction of order.The state transfer differential equations are solved by using the Magnus series expansion,and the transfer matrix of the functionally graded interlayer is obtained.Finally,the reflection and transmission coefficients of various scattering waves are obtained by using the perfect interface conditions,and the numerical results are validated by the energy conservation law.It is shown that the different gradient profiles of functionally graded interlayer have evident influences on the reflection and transmission of elastic waves,and the surface waves are more sensitive to the gradient profile than the bulk waves.(2).Based on the flexoelectric effect,we investigate the dispersion features of elastic waves in an infinite piezoelectric space,the reflection of elastic waves in an infinite piezoelectric half-space and the reflection and transmission of elastic waves in a sandwich piezoelectric slab.The numerical simulations are performed,and the influences of the flexoelectric effect on the elastic wave propagation are discussed.The numerical results are validated by the energy conservation law.It is shown that the flexoelectric effect has evident influences on the elastic wave propagation in the piezoelectric materials,especially,the influences are more evident for the high frequency short wavenumber elastic wave propagation.(3).Based on the semiconductor effect,we investigate the dispersion and attenation features of elastic waves in an infinite piezoelectric semiconductor space,the reflection of elastic waves in an infinite piezoelectric semiconductor half-space and the reflection and transmission of elastic waves in a sandwich piezoelectric semiconductor slab.The numerical simulations are performed,and the influences of the steady carrier density and biasing electric field on the elastic wave propagation are analyzed.It is observed that the piezoelectric semiconductor solid is similar to the standard line viscoelastic solid with respect to the dispersion and attenation features of elastic waves,because two solids both have a frequency sensitive zone.The propagation of elastic waves can be regulated by adjusting the steady carrier density and the biasing electric field,even the acoustoelectric amplification of waves can be realized.(4).Based on the porous effect,we studied the dispersion features of elastic waves in an infinite porous piezoelectric space and the reflection of elastic waves in an infinite porous piezoelectric half-space,and the influences of the constitutive constants characterizing the properties of porosity changes on the dispersion features and the reflection features of elastic waves are discussed.The numerical results are validated by the energy conservation law.It is observed that the porous conatants have evident influences on the wave propagation,especially,the influences are more evident for the volume fraction change wave(VP).The influences of the magneto-electric-elastic functionally graded interlayer,the flexoelectric effect,the semiconductor effect and the porous effect on the propagation of elastic waves in the piezoelectric materials are different,and the semiconductor effect leads to the attenuation characteristics of elastic waves in the piezoelectric materials.By considering these complex piezoelectric theories in the wave propagation problem,we summarize the influences of these effects on wave propagation.These investigations will provide some theoretical guidance for the design of smart devices and structures.