Mechanical Performance and Electrical Resistance Properties of Plain Woven Carbon Fiber-Reinforced Epoxy Composites Under Quasi-Static and Cyclic Loading

This study proposes a novel, sensor-free approach for in situ structural health monitoring of plain woven carbon fiber-reinforced polymers (PWCFRPs) based on their intrinsic electrical resistance behavior under bending fatigue. Using the two-probe method, we monitor electrical resistance changes in real time during three-point bending tests on PWCFRP specimens of two thicknesses (4.0 and 4.7 mm). Static and fatigue tests reveal that thicker specimens exhibit superior bending strength, stiffness, and fatigue life. Crucially, resistance variations closely correspond to damage evolution-from initial matrix cracking and interfacial debonding to final yarn fracture. The observed transition from a negative pressure-resistance effect in early cycles to a sharp resistance increase at failure provides a quantifiable indicator of structural degradation. This correlation enables effective health monitoring without external sensors. The findings establish a foundation for intelligent composite structures capable of self-sensing via the simple and practical two-probe resistance measurement technique. © 2025 Society of Plastics Engineers.