Computer investigation of material properties of heterogeneously polarized porous piezoceramics with metallized pore surfaces

Piezoelectric materials that demonstrate linear coupling of mechanical and electric fields in a wide range of external influences have numerous applications in modern industry. For example, they can be used as active materials... [ view full abstract ]

Piezoelectric materials that demonstrate linear coupling of mechanical and electric fields in a wide range of external influences have numerous applications in modern industry. For example, they can be used as active materials for piezoelectric transducers in hydroacoustic and medical ultrasound applications. Porous piezoceramic has not only less impedance compared to dense piezoceramic but also larger values of thickness piezomodule. However, its stiffness decreases with increase of porosity. In order to increase the stiffness of porous piezoceramic, recently a method of transporting micro- and nanoparticles of various materials into piezoceramic skeleton was introduced. The application of this method allows one to obtain porous piezoceramic materials, for example, with metalized pore surfaces.

This work continues author's investigations of homogenization models for porous piezoelectric composites with metalized pore surfaces. In order to determine effective properties of composite material, we used the effective moduli method and the finite element method with algorithms of building the representative volumes simulating the internal microstructure of the composite. The metallization of the pores is modeled by the boundary conditions of free electrodes and shell elastic finite elements. Next, we simulated nonuniform polarization field around the pores. For this we previously solved the electrostatic problem for the dielectric composite. Further, according to founded electric field, the polarization vector directions have been finding. After that every volumetric finite element of a representative volume was associated with a new coordinate system so that the third axis was chosen codirectional to the element’s polarization vector. As a result we had a representative volume for the piezocomposite with inhomogeneous properties of piezoceramic matrix. The experiments showed that the increase of porosity resulted in the increase of various piezoelectric coefficients and dielectric permittivities. These unusual properties help to improve the use of piezoelectric composites with metallized pore surfaces in hydroacoustics and medical ultrasound.