Core material

A core material formed from thin walls arranged into an array of hexagonal or similar cells, used on edge between face sheets so the cell walls carry compression and shear. It offers very high stiffness and strength for its weight, with common types made from aluminium foil, resin-coated aramid paper and thermoplastics.

The thin, stiff outer layer bonded to each side of a sandwich core, typically a fibre-reinforced laminate or a metal sheet. Face sheets carry the in-plane tensile and compressive loads generated when the panel bends, while the core separates them and carries the shear.

The mass per unit volume of a core material, used as the primary grade designation for structural foams and honeycombs. Higher densities generally bring higher strength and stiffness at the cost of weight, so cores are specified by density alongside thickness and cell or grain structure.

The shear loading carried by the core of a sandwich panel as it bends, transferring load between the two face sheets. Core shear strength and shear modulus are primary selection properties for core materials, and core shear failure is a common design-limiting mode in sandwich structures.