In-plane shear behavior of aluminum hexagonal honeycomb core with random perforations

In lightweight sandwich composite materials, suitable mechanical performance of the core material is required for the efficient transfer of shear loads. Cell wall perforations, orientation, load directionality and boundary conditions, are factors that can influence the structural shear performance of the core. In the present study the elastoplastic behavior of aluminum honeycomb core with random perforations on cell walls under pure shear has been investigated experimentally and examined by numerical simulation. In the investigation, the shear modulus, elastic shear limit, deformation (buckling modes) and failure mechanisms of the honeycomb core have been evaluated. The presence of perforations in honeycomb cell walls reduces the elastic shear modulus in the W direction, while in the L direction a slight increase in stiffness is obtained. Furthermore, perforations influence the onset of elastic buckling and pattern of the obtained buckling modes. The honeycomb shear response was evaluated both under externally applied tension and compression loading to account for differences in load directionality of the testing setup, revealing lower elastic shear modulus under tension compared to compression. Numerical analysis could predict satisfactorily the onset of elastic buckling and the obtained deformation modes with and without the presence of perforations. The results of the present research study highlight the significance of loading conditions and manufacturing parameters on the shear behavior of honeycomb core structures, which need to be taken under consideration when optimizing the mechanical response of honeycomb core structures.