Fracture toughness characterization of phenolic resin and its composite

Abstract The aim of this study is to determine the fracture toughness of phenolic resin and its composite. Fracture tests on phenolic resin resulted in a fracture toughness close to values quoted for unmodified epoxy resins. Composite specimens of glass fiber reinforced phenolic were also tested. The interlaminar fracture toughness in both mode I and mode II failures was determined. The mode I initiation values were lower than the neat resin's toughness. Mode I propagation values were strongly influenced by fiber bridging. The mechanism of fiber bridging was found to be sensitive to specimen dimensions. The effect of fiber bridging on the mode I analysis is discussed. Fiber bridging was also evident in mode II failures. Two different geometries were used for the mode II tests (end loaded split and end notched flexure); a correlation between the results from the two geometries is made.