Mixed-mode I+II fracture characterization of a hybrid carbon-epoxy/cork laminate using the Single-Leg Bending test

This paper describes experimental and numerical studies addressing mixed-mode I+II fracture characterization of a carbon-epoxy/cork hybrid laminate using the Single-Leg Bending test. An equivalent crack length based data reduction scheme applied to the hybrid specimen was developed to evaluate the fracture energy. The proposed method does not require crack length monitoring during the test which is difficult to perform accurately in a tough material, as is the case of cork. It was observed that hybridization is quite effective since stable crack growth occurred even for unstable specimen configurations. Moreover, the more efficient quadratic energetic criterion was found to be representative of the hybrid material fracture, instead of the linear one characterizing the monolithic carbon-epoxy material. The proposed procedure was validated by means of finite element analysis including a new trapezoidal cohesive zone model based on incremental calculation of energy dissipation during fracture.