Continuous carbon fiber polymer‐matrix composites and their joints, studied by electrical measurements

Continuous carbon fiber polymer‐matrix composites and their Joints, as studied by DC electrical measurements, are reviewed. The resistance gives information on the microstructure and allows the self‐sensing of strain, damage and temperature. In the case of composites with dissimilar fibers in adjacent laminae, the Seebeck effect allows temperature sensing, using the interface between laminae as a thermocouple junction. The resistance in the through‐thickness direction can be apparently negative, due to entropy‐driven electron backflow. The longitudinal resistance allows sensing of the glass transition and melting of the thermoplastic polymer matrix. The quality of composite‐composite joints obtained by adhesion or fastening, and of composite‐concrete joints obtained by adhesion, is revealed by resistance measurements.