Homogenization Equivalence Modeling of Honeycomb Bending Considering Regional Deformation Differences

A Nomex aramid paper honeycomb sandwich structure is the core material of the main load-bearing structures in aviation. Macroscopic full-scale refined modeling faces the problems of large mesh quantity and high calculation cost. Homogenization equivalence is the core path to achieve its efficient simulation design. Most of the existing mature equivalent models are based on the ideal assumption that the honeycomb always remains macroscopically straight, without considering the equivalent performance changes caused by the morphological distortion of micro-cells under bending conditions. Therefore, it is difficult to support a high-precision simulation of large-curvature special-shaped honeycomb sandwich structures. This paper takes the over-stretched rectangular lattice aramid honeycomb as the research object. The mechanical parameters of the matrix are calibrated through experiments, and the reliability of the fine shell finite element model is verified (the maximum error of the end-face strain characteristics between simulation and the DIC test is less than 10%). A customized finite element sample matrix for compression bending is designed, and the angle distribution laws of honeycomb cells under different thicknesses and different bending curvatures are extracted. It is found that the cell angle shows a linear change trend along the wall-thickness direction, which is only strongly correlated with the initial geometric parameters and the bending radius. Finally, a semi-empirical model that can quickly predict the morphology of bent honeycomb cells is obtained through fitting. Verified by the glass compression-molding visualization experiment, the maximum relative error of the predicted cell angle is only 5.05%. This research establishes a rapid characterization method for the deformation of honeycomb cells under bending deformation, providing theoretical support for the microscopic homogenization equivalent modeling of curved honeycomb sandwich structures.