Evaluation of resin impregnation using self-sensing of carbon fibers

The wettability of fiber-reinforced composites plays a crucial role in both mechanical properties and the efficiency of the manufacturing process. This is particularly significant in large and intricate composite structures where any flaws can have more severe consequences. In this study, the impregnation of epoxy resin into carbon fiber (CF) mats in-situ was monitored by observing the electrical resistance (ER) behaviors of CFs without any other additional sensors. The ERs of CF and CF tows at various points were measured, while epoxy resin was applied to establish fundamental data on ER behavior during the Vacuum Assisted Resin Transfer Molding (VARTM) process. During the VARTM process, the ERs of CF mats in-situ were compared with the behaviors of micro and sub-micro CFs, along with capturing images of the front flow of epoxy resin. The ER data obtained during the VARTM process was visualized through 3D ER mapping, which allowing for real-time monitoring of the flow front. Ultimately, the resin flow front of epoxy resin into CF mats was successfully monitored using the ER behaviors of CFs themselves.