Group

Structural core materials are lightweight, low-density substances used as the central layer in a sandwich composite structure, which consists of two thin, strong, and stiff facesheets bonded to a thick core. The primary function of the core is to separate the facesheets, increasing the structure's bending stiffness and strength with minimal weight gain—analogous to an I-beam's web separating its flanges. It also provides crucial shear transfer between the faces and absorbs energy from impacts. Common core materials include rigid polymer foams (like PVC, PET, or polyurethane), honeycomb structures (made from aluminum, Nomex® paper, or thermoplastic), balsa wood, and increasingly, syntactic foams (polymer filled with hollow microspheres). The choice depends on required properties like shear strength, compressive modulus, temperature resistance, moisture absorption, and cost.

The applications for sandwich composites with structural cores are dominated by industries where high stiffness-to-weight and strength-to-weight ratios are critical. In aerospace and aviation, they are used in aircraft floors, radomes, control surfaces, and interior panels. The marine industry employs them for hulls, decks, and superstructures of boats and yachts. Wind energy relies on them for the massive blades of turbines. They are also essential in transportation (for truck trailers, rail cars), sporting goods (skis, snowboards, surfboards), and industrial applications. The core material's properties dictate the composite's performance under specific loads; for instance, honeycomb offers very high shear strength, while foams are easier to shape for complex contours. Ongoing innovation focuses on developing sustainable and recyclable cores, thermoformable cores for easier processing, and cores with integrated functionalities like thermal insulation or damage sensing.