Computer Simulation of Composites Consisting of Piezoceramic Matrix with Metal Inclusions and Pores

The problem on determining the effective properties of mixed composites consisting of a piezoceramic matrix with metal inclusions and pores is investigated. Composites with microporosity and mesoporosity are compared. For microporous composites, two-level models of two-phase structures are used. At the microlevel, the effective properties of a piezoceramic material with pores are first determined, and then, at the mesolevel, the homogenization problem for a piezoelectric material with effective properties found at the first stage and with conductive inclusions is solved. Mesoporous composites are considered as three-phase composites with a piezoceramic matrix, inclusions, and pores located at boundaries of inclusions. Homogenization problems are solved numerically in the ANSYS finite element package for representative volumes with closed structures of inclusions and pores. Inclusions and pores are modeled as piezoelectric materials with extreme values of stiffness moduli and dielectric constants. It is noted that this approach preserves the energy balance between the composite medium and the homogeneous reference medium. As an example, calculations of the effective moduli of composites consisting of piezoceramics based on barium titanate, nickel inclusions, and pores are performed. The effective moduli in relation to the volume fractions of inclusions and pores, as well as on the number of mesoscale pores on the boundaries of the inclusions, are investigated. An analysis of the influence of porosity type on the effective properties of the piezocomposites considered is presented.