Finite Element Modeling for Compression Strength Prediction of Honeycomb Cores with Geometric Imperfections Measured Using X-Ray CT Imaging

Abstract

Aluminum honeycomb cores are used in composite sandwich panels to achieve high bending rigidity while maintaining low weight. Geometric imperfections arise in the walls of metallic honeycomb cores during manufacturing, which affects their compression and impact response. This paper presents finite element modeling of metallic honeycomb cores with measured geometric imperfections. The honeycomb cores are modeled using shell geometry reconstructions of images of cores obtained using X-ray Computer Tomography. Flatwise compression responses of the cores are computed using finite element analyses of honeycomb cores for different representative volume element (RVE) sizes and boundary conditions. It is found that the compression response of the 10x11 cells RVE models can be predicted by the average of single RVE cell models sampled from the 10x11 cells RVE domain. However, this requires appropriate choice of boundary conditions. The non-periodic nature of the imperfection and the variation in geometric imperfection in the double and single thickness walls of the honeycomb core cells lead to interactive buckling of these walls and mode jumping during the amplification of initial imperfections under compression. These interactions play a significant role in the compression response and, therefore, the RVE size and boundary condition choices made should ensure this interaction are accurately captured.