A general formulation of the method of the reverberation-ray matrix (MRRM) based on the state space formalism and plane wave expansion technique is presented for the analysis of guided waves in multilayered piezoelectric structures. Each layer of the structure is made of an arbitrarily anisotropic piezoelectric material. Since the state equation of each layer is derived from the three-dimensional theory of linear piezoelectricity, all wave modes are included in the formulation. Within the framework of the MRRM, the phase relation is properly established by excluding exponentially growing functions, while the scattering relation is also appropriately set up by avoiding matrix inversion operation. Consequently, the present MRRM is unconditionally numerically stable and free from computational limitations to the total number of layers, the thickness of individual layers, and the frequency range. Numerical examples are given to illustrate the good performance of the proposed formulation for the analysis of the dispersion characteristic of waves in layered piezoelectric structures.
GUO YongQiang1, CHEN WeiQiu2,3 & ZHANG YongLiang4 1 Key Laboratory of Mechanics on Disaster and Environment in Western China, Ministry of Education, and School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000, China
We theoretically study the indentation response of a compressible soft electroactive material by a rigid punch. The half-space material is assumed to be initially subjected to a finite deformation and an electric biasing field. By adopting the linearized theory for incremental fields, which is established on the basis of a general nonlinear theory for electroelasticity, the appropriate equations governing the perturbed infinitesimal elastic and electric fields are derived particularly when the material is subjected to a uniform equibiaxial stretch and a uniform electric displacement. A general solution to the governing equations is presented, which is concisely expressed in terms of four quasi-harmonic functions. By adopting the potential theory method, exact contact solutions for three common perfectly conducting rigid indenters of fiat-ended circular, conical and spherical geometries can be derived, and some explicit relations that are of practical importance are outlined.
Thickness effects on the ME coefficient αME and electromechanical resonance frequency of Metglas/PZT/Metglas tri-layered laminates are investigated. The thickness of the magnetic plate is changed by assembling different numbers of the Metglas thin sheets （30μm for each layer） while the PZT plate is maintained at constant thickness （0.5 mm）. At 1 kHz of the applied alter- nating magnetic field, only one peak presents in the ME coefficient （OCME） versus static magnetic field （Hs） curve. As the thickness ratio n increases, the peak value of αME first increases and reaches a maximum at approximately n = 0.519, and then decreases afterward. The peak position （Hoptim） moves steadily toward a higher value as n increases. It is suggested that the re- laxation factor k of the magnetic phase is reduced as n increases, causing the decrease of the piezomagnetic coefficient d11,m and the increase of Hoptim. By employing the micromechanics model and considering the degradation of dll,m with n, an opti- mized thickness ratio of 0.5 is predicted, which is in agreement with the experimental observations. The resonance frequency of the laminate increases with n, which is consistent with the calculation using a straightforward mixture law.
Many distinguished properties of epitaxial ferroelectric thin films can be tunable through the misfit strain.The strain tunability of ferroelectric and dielectric properties in epitaxial lead titanate ultrathin films is numerically investigated by using a phase field model,in which the surface effect of polarization is taken into account.The response of polarization to the applied electric field in the thickness direction is examined with different misfit strains at room temperature.It is found that a compressive misfit strain increases the coercive field and the remanent polarization while a tensile misfit strain decreases both of them.The nonlinear dielectric constants of the thin films with tensile misfit strains are much larger than those of the thin films without misfit strains,which are attributed to the existence of the a/c/a/c multiple domains in the thin films under tensile misfit strains.
Jie Wang~(a)) School of Aeronautics & Astronautics,Zhejiang University,Hangzhou 310027,China
The performance of dielectric elastomer （DE） transducers is significantly affected by viscoelastic relaxation-induced electromechanical dissipations. This paper presents an experi- mental study to obtain the rate dependent stress-stretch relation of DE membranes （VHBTM9473） subjected to pure shear like loading and electric loading simultaneously. Stretching rate depen- dent behavior is observed. The results also show that the tensile force decreases as the voltage increases. The observations are compared with predictions by a viscoelastic model of DE. This experiment may be used for further studies of dynamic electromechanical coupling properties of DEs.
Shaoxing QuKe LiTiefeng LiHanqing JiangMiao WangZhenhua Li
<正>The static and dynamic problems of an imperfectly bonded,orthotropic,piezoelectric laminate in cylindrical ...
Yun-ying ZHOU,Wei-qiu CHEN School of Aeronautics and Astronautics,Zhejiang University,Hangzhou 310027,China Chao-feng L Department of Civil Engineering,Zijingang Campus,Zhejiang University,Hangzhou 310058,China
<正>This work presents an approach named direct displacement method to investigate the free axisymmetric vibrat...
Yun WANG School of Mechanical Engineering,Hangzhou Dianzi University,Hangzhou,Zhejiang 310018,China Rong-qiao XU,Hao-jiang Ding Department of Civil Engineering,Zhejiang University,Hangzhou,Zhejiang 310058,China
