Impedance spectroscopy for progressive damage analysis in woven composites

Current applications require an understanding of the relationships that exist between the functional characteristics of composite material systems and the long-term behavior of those materials under mechanical loading. Using electrochemical impedance spectroscopy, a method was established and used to characterize damage initiation and progression in thin woven glass/epoxy composites. Monitoring the evolution in residual strength due to out of plane bending fatigue, a relationship was established between impedance at different frequencies of excitation and the development of damage in the material. When compared to common methods of measuring change in physical properties or visual damage, the metrics defined by impedance spectroscopy measurements were found to show larger, more consistent, and clearer distinctions as damage developed.