Elastic Waves In Magnetoelectric And Viscoelastic Functionally Graded Couple-stressed Plates

With the development of miniaturized intelligent devices,nanomaterials and structures with single properties can not meet the requirements of some complex and extreme environments.Magnetoelectric materials and viscoelastic materials composed of functional gradient materials(FGMs)show great application potential in the field of micromaterials,and are widely used in intelligent devices and micro-organ.In engineering,functionally gradient microstructures usually bear dynamic working loads in the form of elastic waves.The research of the wave propagation characteristics can provide a theoretical basis for the design,performance characterization and material property inversion of micro/nano acoustic devices.The existence of the scale effect makes micro/nano-materials show obvious characteristic differences,which leads to the emergence of new mechanical properties.Due to the lack of characteristic scale parameters to characterize the size effect,the classical theory can not be used to study the mechanical properties of microstructures.Firstly,based on the modified couple stress theory,the Legendre orthogonal polynomial method(LOPM)is applied to solve the reflection and transmission behavior of elastic waves in functionally graded magneto-electro-elastic(FGMEE)microstructures and the dispersion characteristics of guided waves in FGMEE microstructures.Then,the extended analytical integral Legendre polynomial method(AILPM)and Kelvin-Voigt viscoelastic model are combined to solve functionally graded viscoelastic(FGVE)microstructures.Research on wave characteristics of FGMEE microstructures: Firstly,the reflection and transmission behaviors of elastic waves in FGMEE microstructures are solved.The correctness of the polynomial solution method is verified by the global matrix method(GMM).The influences of couple stress effect,magnetoelectric effect and non-homogeneous on the reflection and transmission behavior of elastic waves are discussed.The results show that the non-homogeneous changes the critical angle and avoids some resonance frequencies.In addition,the magnetoelectric effect and couple stress effect on reflection and transmission are mutually inhibited.Then,the dispersion characteristics of guided waves in the FGMEE microstructure are solved.The couple stress effect,magnetoelectric and non-homogeneous effect on dispersion characteristics of guided waves are discussed.The results show that the couple stress effect,the first two modes of Lamb wave converge to two higher Rayleigh wave velocities respectively.Except for the first mode,the influence of the couple stress effect is suppressed by non-homogeneous,and the influence becomes more obvious with the increase of wavenumber.Research on wave characteristics of FGVE microstructures: Firstly,the reflection and transmission behaviors of elastic waves in FGVE microstructures are solved.The correctness of the solution is verified by GMM and existing literature.The couple stress effect,viscoelastic effect,non-homogeneous on reflection,transmission and energy dissipation are discussed.The results show that the couple stress effect weakens the energy dissipation caused by the viscoelastic effect.The couple stress effect weakens the viscoelastic effect,and the viscoelastic effect strengthens the couple stress effect.Then,the dispersion characteristics of guided waves in FGVE microstructures are solved.The viscoelastic effect,couple stress effect and non-homogeneous on dispersion characteristics are analyzed.The results show that the couple stress effect not only increases the wave velocity,but also strengthens the influence of non-homogeneous on the velocity.