Numerical simulations and experimental study of frequency-dependent dielectric properties of composite material with stochastic structure

Results of a computer modeling and analytical estimations of frequency-dependent dielectric properties of a composite material with stochastic structure in the frequency range from 1 mHz to 1 kHz are presented and are compared with experimentally obtained parameters. The studied composite was a mixture of materials having considerably different properties, where the inclusion phase with the volume fraction of 0.31 was distributed randomly in the host material forming a complex three-dimensional structure. For such composite dielectric, the applicability of bounds on the effective complex permittivity and different known mixing formulas for estimating of the effective parameters is examined. The numerical simulations performed using measured frequency-dependent characteristics of the constituents and the reconstructed three-dimensional stochastic structure of the composite, yielded values of the effective dielectric permittivity which were in good agreement with the measured ones. Frequency variations of the computed distributions of the microscale electric field and energy losses in the bulk of the studied composite dielectric are presented and discussed.