What are sandwich structures?
Sandwich structures consist of a lightweight core material covered by face sheets on both sides. Although these structures are lightweight, they have a high flexural stiffness and buckling strength. Hence, sandwich structures are an essential part of modern lightweight construction.
Core materials are:
- rigid foams
- thermoplastic cores
Resin impregnated woven fabrics or other carrier materials (so-called prepregs) can be used as face sheets. The basic properties of sandwiches, like flame retardance, mechanical properties and surface quality, are adjusted by selecting the resin, the woven fabrics and the core materials according to the desired application (e.g. aircraft interiors, facade facing).
Present developments include the development of new core materials as well as the development of prepreg resins for face sheets.
The novel prepreg resins are specifically adjusted reactive resins which meet specific requirements. These requirements are for example a plain surface where the structure of the subjacent core-material is not apparent (so-called telegraphing). Additionally, certain production parameters are required and the prepregs must have a sufficient shelf-life at room temperature. Many users of sandwich structures require a high flame retardance, which is influenced significantly by the face sheets because face sheets make-up a large part of the overall weight.