Pure mode I and II interlaminar fracture characterization of carbon-fibre reinforced polyamide composite

In this work, interlaminar fracture characterization of carbon-fibre reinforced polyamide composite was studied experimentally and numerically. The double cantilever beam and end notched-flexure tests were performed to determine interlaminar fracture toughness under pure mode I and pure mode II, respectively. Equivalent crack length based procedures were used to assess the Resistance-curves, which allowed obtaining the fracture energies under self-similar crack growth. It was observed that toughness values are markedly higher than the ones obtained for typical carbon-epoxy composites and other thermoset based composites. A cohesive zone model with trapezoidal softening law was employed to simulate the fracture process in both tests. An inverse procedure was followed to determine cohesive parameters defining laws representative of the fracture process. Overall, good agreement was obtained revealing the suitability of the procedure and the appropriateness of the obtained laws. The obtained fracture energies for this thermoplastic composite are quite superior when compared to the thermoset based ones, making this material a promising candidate to replace thermoset matrices in many structural applications.