Sandwich structures bearing resorcinol-formaldehyde aerogel honeycomb cores

Abstract

Light-weight materials bearing additional functionality may contribute in future towards saving energy within the transport sector. Due to their high compressive strength and capacity to absorb energy upon impact, honeycombs have long been used as core constituent of sandwich structures. However, despite their favourable mechanical properties, such sandwich structures do not generally act as thermal insulators, as the honeycombs are typically filled with air, thus contributing to convective heat transfer. One concept for reducing the heat transfer of honeycomb sandwich structures is based on filling the honeycombs with aerogel materials. Aerogels are nanoporous lightweight materials with super-insulating properties. To date, only a few examples of honeycombs filled with aerogels are known, but these composites are basically limited to aerogels combined with honeycombs from paper or aramid. Here, we report on resorcinol-formaldehyde aerogels, honeycombs made from aramid and aluminium, respectively, as well as aerogel filled honeycombs and sandwich structures resulting from lamination of filled honeycombs with aluminium cover sheets. Apart from the production process, the mechanical behaviour under compression and thermal conductivity are evaluated. Furthermore, simulative tools were employed in order to describe and predict the mechanical behaviour of the aerogel-honeycomb composites. The obtained results will be presented and discussed.