Magnetoelectric Effect And Scattering Of SH Waves In Nano Piezoelectric-Piezomagnetic Composites

Piezoelectric-piezomagnetic composites are new functional materials. Such composites can be able to transform electric energy into magnetic energy and vice versa, which make them very promising for a wide range of applications, such as sensing, transduction, signal processing and control, and so on. From the material scale, piezoelectric-piezomagnetic composites can be divided into bulk materials and nano materials. Nano materials are easy to realize the regulation of magnetic-electric conversion, and to meet the requirements of the relevant micro devices of engineering. Therefore, it is significant to study the magnetoelectric properties and fundamental mechanical problems in nano piezoelectric-piezomagnetic composites. Based on the surface/interface model, several problems of piezoelectric-piezomagnetic nano fibers composites under anti-plane deformation are investigated in this dissertation. The main research contents are as follows:Magnetoelectric properties of piezoelectric-piezomagnetic composites with elliptical nano fibers. First of all, based on the complex function theory and conformal mapping method, the exact closed-form solutions of magneto-electro-elastic in matrix and fiber are obtained under the far-field uniform magneto-electro-elastic loads. Then applying the Mori-Tanaka mean-field method, the expression of the effective properties of nano piezoelectric-piezomagnetic fiber composites is obtained. Numerical examples are given to show the influences of the fiber volume fraction, interface effect, the ratio of the semi-axes and the material composite types on magnetoelectric properties.Magnetoelectric effects of piezoelectric-piezomagnetic composites with coated circular nano-fibers. By using the series expansion method, the exact closed-form solutions of magneto-electro-elastic fields in matrix, coating and fiber are obtained under the far-field uniform magneto-electro-elastic loads. Based on Mori-Tanaka mean-field method, the magnetoelectric properties of coated circular nano fiber composites are connected with the phase material properties, interface parameters and geometry is established. Numerical examples are indicate to show the effect of component material properties, interface effects, the radius of fiber and the thickness of coating on the effective magnetic coefficients.Scattering of SH waves and concentrating of magneto-electro-elastic fields in a nano piezoelectric(or piezomagnetic) fiber-piezomagnetic(or piezoelectric) matrix. By means of the wave function expansion method, the analytical solution of scattered waves, reflected wave and transmitted wave are obtained. The distributions of dynamic magneto-electro-elastic field around the fiber is calculated by numerical examples under the action of SH wave and steady-state electric(magnetic) fields.