Estimating electrical conductivity of multi-scale composites with conductive nanoparticles using bidirectional time marching percolation network mapping

A computationally efficient approach is developed to determine electrical conductivity of large specimens of multi-scale composites composed of electrically conductive nanoparticles and nonconductive matrix and micro-scale reinforcements. As a test case, the paper studies nanocomposites and multi-scale fiber/polymer composites of carbon nanotubes. Fraction of percolating carbon nanotubes is defined as a metric for estimating electrical conductivity of composites with intermediate volume fraction of carbon nanotubes. The results indicate that for multi-scale composites with high fiber/reinforcement volume fraction, the simulation size needs to be in millimeters whereas for multi-scale composites with low fiber/reinforcement volume fraction, smaller simulation sizes (in 100s of microns) are sufficient. The present research is a first step towards efficient design of fiber composites for electromagnetic applications such as lightening protection and electromagnetic shielding.