By utilizing 3D printing technology, experimental three-point bending (TPB) tests, and finite element analysis, six honeycomb structures with a variety of overall Poisson’s ratios (PR) are studied and compared in terms of bending properties and failure mechanisms. Four novel honeycombs that are designed by hybridizing hexagonal and re-entrant units outperform benchmark conventional honeycombs in terms of load-carrying capacity. Architected hybrid geometry honeycombs with zero PR show excellent specific energy absorption capability in comparison to benchmark honeycombs, absorbing approximately 136.9% and 475.1% more energy under TPB. 3D-printed honeycombs consisting of hexagonal units face layer separation damage mode under bending, while honeycombs with re-entrant cells in their lattice fail with joint shear due to the angle of their struts towards loadings. Designing honeycombs with a hybrid geometry lattice can enhance the load-carrying capacity, specific energy absorption, flexibility, and flexural modulus of the structure under bending. Due to their superior performance, the proposed architected hybrid geometry honeycombs with various Poisson’s ratios own promising applications in automotive, protective, and construction industries.

Honeycomb sandwich panels are widely used in marine, aerospace, automotive and shipbuilding industries. High strength to weight and excellent energy absorption are features that make these structures unique. Foam filling the honeycomb core enhances the mechanical properties of sandwich panels considerably. In the present study, the buckling behavior of Nomex honeycomb core/glass-epoxy face sheet sandwich panel for both bare and foam-filled honeycomb core is investigated numerically and experimentally, considering the viscoelastic properties of the sandwich panel. Indeed, the viscoelastic properties of the composite face sheet and foam are determined by relaxation test and are implemented in ABAQUS using VUmat code. The finite element method is also performed using ABAQUS to model the buckling behavior of the sandwich panel incorporating both elastic and viscoelastic material behaviour. The effects of composite face sheet lay-up, core thickness, core cell size, and foam filling are also evaluated. The experimental and numerical results show that the foam increases the critical buckling load and energy absorption.