A universal equivalent circuit model for the impedance response of composites

An equivalent circuit model has been developed to describe the impedance response of composites with insulating or conductive particles or fibers. Required inputs are the matrix conductivity, the "intrinsic conductivity" of the particles, and their volume fraction. The model has general applicability to systems involving moderately conductive matrices, insulating or conductive particles/fibers, and, in the case of conducting particles, the presence of a high impedance "coating" element on the particle surfaces. Ramifications for the use of impedance spectroscopy in the characterization of composite properties and the monitoring of their performance under load are discussed. (C) 2003 Kluwer Academic Publishers.