Dimension reduction model for sandwich panels with novel triangular chiral honeycomb using variational asymptotic method

The triangular chiral (Tri-Chi) honeycomb is a novel negative Poisson's ratio structure, featuring fully triangular cells inspired by the anti-tetra chiral design. This work aims to reveal the deformation mechanisms of the TriChi honeycomb and employs the variational asymptotic method to determine the effective plate properties of sandwich panels with Tri-Chi honeycombs (i.e., SP-TCH). Based on this, a 2D dimension reduction model (2D-DRM) is developed, and the warping functions are solved through asymptotic analysis of the leading terms in the energy functional. Comparative analysis with the 3D FE model demonstrates that the 2D-DRM exhibited maximum errors of only 6.83% and 2.93% respectively in analyzing tension-bending coupling behavior and natural frequency, with the computational efficiencies being improved by approximate 55-fold and 32-fold, respectively. Furthermore, the parameter analysis indicate that the structural stiffness and natural frequencies of SP-TCH were higher than those of stiffened triangle honeycomb sandwich panel with the same dimensions and materials. The facesheet layup design had a significant impact on the equivalent stiffness and vibration characteristics, whereas the included angle had a significant influence on the Poisson's ratio of the Tri-Chi core layer, leading to a reversal from a negative to a positive ratio as the included angle increased.