Today, the exploitation of the economical advantages of weight reduction has become essential for many industries.
It is well known that the task distribution in sandwich construction enables high stiffness and strength for lightweight panels and parts. Sandwich construction with low cost core materials can not only be more lightweight but also more cost effective, especially because the advancement and automation of production processes results in a reduction of the production cost for lightweight sandwich panels.
The combination of materials to utilize their favorable properties is the basic idea of composites engineering. With a monolithic material, a thickness increase leads to an increase of both weight and material cost of a panel.
Sandwich constructions use the fact that the core of a panel that is loaded in bending does not carry much in-plane stresses and does not represent the surface of the panel. The core can thus be made from a different, more lightweight and/or less expensive material. Sandwich construction takes the different demands on the central layer (core) and surface layers (skins) into account.
The selection and optimisation of the different material layers according to their demands enables to improve the weight and/or cost specific properties of the construction. The potential economic advantage of low cost core materials is as big as the potential weight saving due to low density core materials.
The support of the skins (to prevent relative displacements of the skins out-of-plane and in-plane) is the main task of every sandwich core material, thus a classification should be made based on how this task is fulfilled by the different core materials. Honeycombs are used in aerospace industries since many decades as the preferred core material for very light and strong sandwich panels and structures. From all sandwich core materials honeycombs enable the best mechanical performance per weight, thus they offer the largest potential for material cost savings.