Interfacial evaluation of carbon fiber/epoxy composites using electrical resistance measurements at room and a cryogenic temperature

Interfacial properties between fiber and matrix were evaluated using an electrical resistance (ER) fragmentation method. The single carbon fiber (CF) tensile test was performed in conjunction with electrical resistance measurements. The relationship between tensile properties of single carbon fiber specimens and the electrical resistance ratio (ERR) was investigated. The data showed a linear relationship between these properties. Fragmentation specimens were tested under tensile loading, and it was observed that, due to stress transfer from the matrix to the reinforcing fiber, the single carbon fiber broke first. The stress distribution along the carbon fiber was monitored via electrical resistance changes. ER fragmentation measurements were performed to predict CF fractured strength embedded in epoxy by an empirical formula of CF tensile results. These interfacial properties of CF epoxy composites were measured at room and a cryogenic temperature. Work of adhesion between the carbon fiber and the matrix was measured to verify the results of the ER fragmentation method, and the two procedures yielded consistent results and conclusions.