Mixed-mode I plus II fracture characterisation of a honeycomb/carbon-epoxy sandwich panel using the asymmetric single-leg bending test

The Asymmetric Single-Leg Bending (ASLB) test was employed to obtain the fracture energy of a honeycomb/ carbon-epoxy sandwich panel under mixed-mode I + II loading. A data reduction method lying on beam theory, specimen compliance and equivalent crack length concepts was employed to get the experimental Resistancecurve (R-curve), which allows determination of the mixed-mode fracture energy. Numerical analysis including cohesive zone modelling was used for validation and as a suitable partition method useful to estimate the mode ratio. In view of the observed non-linear behaviour, a mixed-mode I + II trapezoidal cohesive zone model and the quadratic energetic criterion were considered in the simulations. Overall, it can be concluded that the ASLB test is appropriate for mixed-mode I + II fracture characterisation of sandwich panels under predominant mode I.

Automated summary

The Asymmetric Single-Leg Bending (ASLB) test was utilized to determine the fracture energy of a honeycomb/carbon-epoxy sandwich panel subjected to mixed-mode I + II loading. A data reduction method based on beam theory, specimen compliance, and equivalent crack length concepts was employed to establish the experimental Resistance curve (R-curve) for determining the mixed-mode fracture energy. Numerical analysis with cohesive zone modeling was employed for validation and as a suitable partition method for estimating the mode ratio. Given the observed nonlinear behavior, a mixed-mode I + II trapezoidal cohesive zone model and the quadratic energetic criterion were considered in the simulations.