Multi-scale characterization and in-plane crushing behavior of the elliptical anti-chiral honeycomb.

• A novel elliptical anti-chiral (EAC) honeycomb structure is proposed by replacing the straight cell walls of the criss-cross anti-chiral (CAC) honeycomb with elliptical cell walls. • Both numerical and experimental results reveal the existence of a plateau stage and an enhancement stage in the stress–strain curves of the EAC honeycomb. • Larger semi-axis length ratio results in larger plateau stress and densification strain, while smaller semi-axis length ratio means larger initial peak stress and plateau strain. • The empirical formulas of critical impact velocity and plateau stress are further derived. Honeycombs with anti-chiral (AC) unit cells are found to have auxetic properties and enhanced energy absorption capacities than regular hexagonal honeycombs. To further improve the energy absorption capacity, by replacing the straight cell walls of the criss-cross anti-chiral (CAC) honeycomb with elliptical cell walls, a novel elliptical anti-chiral (EAC) honeycomb is proposed in this paper. The in-plane crushing response of the EAC honeycomb is investigated numerically under different impact velocities. The numerical modeling method in ABAQUS software is validated by the compression test data of 3D-printed EAC honeycomb specimens. Both experimental and numerical results reveal that the EAC honeycomb has a plateau stage and an enhancement stage in the stress–strain curve. The empirical formulas of critical impact velocity and plateau stress are further derived, which is in good agreement with the numerical simulation results. The parameter analysis further shows that the microstructural parameters have a great influence on the crushing strength of the EAC honeycomb. Under the same impact velocity, larger semi-axis length ratio results in larger plateau stress and densification strain, while smaller semi-axis length ratio means larger initial peak stress and plateau strain. [ABSTRACT FROM AUTHOR]