PVC foam core

Closed-cell thermoplastic polyester foam used as a structural sandwich core. It is thermoformable, recyclable and often manufactured with recycled content, and its fatigue and processing performance has made it a common choice in wind turbine blades and transport structures.

Closed-cell styrene acrylonitrile foam used as a structural sandwich core, valued for its high toughness and elongation combined with good static strength. Its damage tolerance has made it popular for boat hulls and other impact-prone sandwich structures.

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.

Core sheet cut with a grid of slits or kerfs, often combined with a scrim backing, so that it can conform to curved mould surfaces. The cuts also act as channels for resin flow during infusion, although they increase resin uptake and therefore the finished weight of the panel.

The lightweight central layer of a sandwich construction, bonded between two thin, stiff face sheets to raise a panel's bending stiffness with minimal added weight. Common structural cores include polymer foams, honeycombs, end-grain balsa and syntactic materials, each specified by density, thickness and shear properties.