Impact Damage and Energy-absorbing Characteristics and Residual In-plane Compressive Strength of Honeycomb Sandwich Panels

An experimental study of the in-plane compressive behavior of both aluminium and nomex composite sandwich panels with 8 ply carbon/epoxy skins was conducted. All sandwich panels were impact-damaged with a range of impact energies from 1 to 55 J. Dominant damage mechanisms were found to be core crushing, skin delamination, and fracture with the former two absorbing most of the impact energy. While the intact panels failed in region close to one loaded end, all the impact-damaged nomex panels failed around the mid-section region. Two thirds of the aluminium panels also failed in the mid-section region and one third failed in the loaded end region. The presence of the core played a unique role in in-plane compression with a substantial stabilizing support to the skins, which counteracted the deleterious effect of impact damage. The in-plane compressive behavior has shown the combined effects of impact damage and the core in a complex manner.