Performance evaluation of composite sandwich structures with additively manufactured aluminum honeycomb cores with increased bonding surface area

Modern aerostructures, including wings and fuselages, increasingly feature sandwich structures due to their high-energy absorption, low weight, and high flexural stiffness. The face sheet of these sandwich structures are typically thin composite laminates with interior honeycombs made of Nomex or aluminum. Standard cores are structurally efficient, but their design cannot be varied throughout the structure. With additive manufacturing (AM) technology, these core geometries can be altered to meet the design requirements that are not met in standard honeycomb cores. This study used a modified aluminum honeycomb core, with increased surface area on the top and bottom, as the core material in sandwich panels. The modified honeycomb core was produced through the laser powder bed fusion method. The behavior of the modified sandwich composite panels was evaluated through three-point bend, edgewise compression, and impact tests, and their performance was compared to that of a conventional honeycomb core sandwich panel. The three-point bend test results indicated that the sandwich structure's ultimate shear strength improved by 12.6% with the modified honeycomb core. Additionally, the displacement at the failure of the structure increased by 11%. The edgewise compression tests showed that the ultimate edgewise compressive strength improved by 19.1% when using the modified core. The impact test results revealed that the peak force increased by 8% and the energy-absorbing capacity of the sandwich structure increased by 20% with the use of the modified honeycomb core.

Automated summary

Traditional honeycomb core materials cannot meet different design requirements, but the additive manufacturing technology allows for the alteration of honeycomb core geometries. In this study, a modified aluminum honeycomb core was used as the core material in sandwich panels, and its performance was evaluated through three-point bend, edgewise compression, and impact tests, compared to a conventional honeycomb core sandwich panel. The results showed that the modified honeycomb core improved the shear strength, displacement at failure, edgewise compressive strength, peak force, and energy-absorbing capacity of the sandwich structure by certain percentages.