Electrical Conductivity in Fibrous Composites

Carbon fiber and other fibrous composites are widely used in structural components for wind turbines and aircraft. These applications not only require high strength and low weight but also tailored electrical properties. Designing new composites that can resist lightning strikes or be used in bioelectronics relies on accurately predicting their electrical conductivities. Yet most models of conductivity in these composites lack a geometrically meaningful basis, particularly if applied far from the percolation threshold which often occurs in the earliest 1% of the composite design space. An electrical model that is grounded in real fiber geometries and arrangements is derived. New equations are obtained, combining materials science and network physics, that accurately predict individual fiber overlap, neighbor distributions, and percolation thresholds in systems of overlapping shapes. Combining these equations with the new electrical model of a “foamy cluster”, yielded excellent predictions of conductivity in many different types of fibrous composites.