Finite element simulation and analysis of the dielectric properties of unidirectional aramid/epoxy composites

Aramid fiber reinforced composites have drawn much attention due to outstanding mechanical and dielectric properties. Dielectric properties should be predicted exactly when such composites are used as electromagnetic functional materials. A simulation method was proposed to predict the effective dielectric constants of unidirectional aramid/epoxy composites in this study. Randomly planar distributed 3D models were created to describe the microstructures of the composites. Parallel and series models were calculated by classical formulas and finite element method to verify the simulation. The distributions of aramid fibers and the dielectric anisotropy of unidirectional composites were analyzed. Dielectric measurements were carried out by the rectangular waveguide method in X-band and excellent agreements between simulations and experiments were observed. The compression of aramid fibers and interface effect were taken into account to improve the forecasting precision. Comparative analysis was conducted between our simulation method and classical formulas, and it was found that the Maxwell-Garnett model gives the best fit to the simulation. In addition, the effect of the fiber orientation in electric field was analyzed. POLYM. COMPOS., 39:E2226–E2233, 2018.