# Theoretical method for calculation of effective properties of composite materials with reconfigurable microstructure: electric and magnetic phenomena

## TL;DR

This paper introduces a theoretical method to predict how the electric and magnetic properties of reconfigurable composite materials change under external fields, validated by experiments on magnetorheological elastomers.

## Contribution

The paper develops a field-dependent extension of the Bruggeman-Landauer approximation for calculating effective properties of composites with reconfigurable microstructures, including nonlinearity effects.

## Key findings

- Qualitative agreement with magnetodielectric experiments.
- Quantitative match for magnetic permeability.
- Effective prediction of property changes in field-controlled smart materials.

## Abstract

We propose a theoretical approach for calculating effective electric and magnetic properties of composites with field-dependent restructuring of the filler. The theory combines the Bruggeman-Landauer approximation extended to a field-dependent (variable) percolation threshold with the approximate treatment of nonlinearity of material properties. Theoretical results are compared with experiments on magnetorheological elastomers, which in the context of investigated phenomena are often called magnetoactive elastomers (MAEs). In MAEs with soft polymer matrices, the mutual arrangement of inclusions changes in an applied magnetic field. This reorganization of the microstructure leads to unconventionally large changes of electrical and magnetic properties. Obtained theoretical results describe observed phenomena in MAEs well. Qualitative agreement between theory and experiment is demonstrated for the magnetodielectric effect. In the case of magnetic permeability, quantitative agreement is achieved. The theoretical approach presented can be useful for development of field-controlled smart materials and design of smart structures on their basis, because the field dependence of physical properties can be predicted.

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Source: https://tomesphere.com/paper/1903.11031