Modeling and confrontation of dielectric mixing laws through numerical simulation and experimental characterization of titanate-based composite materials

Abstract

This thesis focuses on the analysis, characterization, and modeling of the dielectric properties of composite materials under quasi-static conditions. Two-dimensional simulations were performed using the finite element method on binary composites consisting of an epoxy resin matrix and ellipsoidal ceramic inclusions randomly distributed according to three statistical distributions (normal, log-normal, and Rayleigh). The study was conducted on three composites with distinct charge permittivities (εi = 80, 400, and 3600) by varying key parameters such as charge concentration, particle distribution, and particle size and morphology to assess the impact of each parameter on the overall effective permittivity of the material. The values obtained from the FEM simulation were compared to several classical and modified analytical models, allowing the identification of the most relevant distributions for predicting dielectric behavior. The results from this work offer essential elements for the optimization of materials for energy storage and conversion, sensors, and various electronic applications, by providing a thorough understanding of their performance before experimental realization.