Experimental and Numerical Investigation of Metal Foam-Filled Ultrathin Aluminum Honeycomb Sandwich Cores Under Axial Crushing: Effects of Cell Geometry and Wall Thickness on Crashworthiness Parameters

Abstract

This study presents an experimental and numerical investigation of the crashworthiness behavior of the closed-cell aluminum foam-filled hexagonal honeycomb structures under quasi-static compression. Honeycomb cores made from AA3003-H18 aluminum alloy with cell sizes of 12 mm and 19 mm were filled with closed-cell aluminum foam of 200 kg/m³ density, to evaluate the effect of cell geometry and cell wall thickness (0.05–0.2 mm) on key crashworthiness parameters i.e. peak crushing force (F_peak), mean crushing force (F_mean), total energy absorption (EA), specific energy absorption (SEA), and energy distribution in linear, plateau and densification region. Quasi-static compression tests were conducted using a Universal Testing Machine (UTM), while numerical simulations were carried out using the explicit finite element code LS-DYNA^®. Numerical results show good agreement with the experimental results, with crashworthiness parameter precision of above 90%, thus validating the numerical simulation approach. Compared to empty honeycomb structures, the foam-filled configurations indicate enhanced performance. In all configurations, the plateau region consistently represented the primary phase of energy absorption, comprising more than 50% of the total energy. At thinner walls, 19 mm cells benefited from greater foam volume and foam-wall interaction, while at higher thicknesses, 12 mm cells achieved superior performance through stable plastic folding. These results provide insights into the foam-filled honeycomb composites as efficient crashworthy structures for automotive, aerospace, and protective applications.