The pursuit of ultra-lightweight, high-efficiency load-bearing structures has established carbon fiber reinforced polymers as a cornerstone of modern aerospace engineering . However, the structural efficiency of solid composites diminishes in bending-dominated applications, where material near the neutral axis remains underutilized. Sandwich construction addresses this limitation by separating two high-strength faceplates with a lightweight core, increasing the second moment of area with a minimal mass penalty . This approach enables superior flexural stiffness-to-weight performance, making it ideal for aerospace, transportation, and offshore applications.

Recent innovations in composite sandwich structures have focused on overcoming the limitations of conventional foam and honeycomb cores, which typically restrict internal accessibility, recyclability, and geometric adaptability . Modular continuous-fiber lattice cores, fabricated via robotic dry winding of carbon fibers on sacrificial 3D-printed scaffolds, demonstrate the potential for ultra-lightweight all-composite sandwich beams with highly open core structures . These modular units achieve relative densities of approximately 0.18-0.19 and can be stacked and bonded between CFRP faceplates, enabling topology-tunable composite structures . Testing has shown that all configurations exhibit progressive, non-brittle deformation with significant displacement capacity .

The combination of additive manufacturing with composite materials is enabling new approaches to lightweight sandwich structures. Research on composite molding sandwich structures incorporating Kagome lattice cores produced via additive manufacturing, along with carbon fiber facesheets, has demonstrated significant improvements in structural mechanics . These structures achieved specific strength improvements of 23.91% to 75.94% compared to integrated molding structures, highlighting the advantages of hybrid manufacturing approaches . The use of accurately contoured orthogonal glass fiber fabric designed to fit the interface geometry as a bonding layer provides remarkable adhesion effectiveness with minimal structural weight penalty .

For deep-sea applications, aerospace composite materials are being adapted for demanding subsea environments. A novel composite structure pressure hull for full-ocean-depth underwater vehicles uses a carbon fiber cylindrical shell as the primary load-bearing structure, achieving a 48% reduction in the buoyancy factor compared to traditional metallic designs . The successful deployment of this technology on the "Sea-Wing 11000" underwater glider demonstrates the practical application of aerospace-inspired composite designs in extreme marine environments . The future of high-strength structural foam and advanced composite materials lies in the continued convergence of aerospace and offshore engineering, with modular designs, additive manufacturing, and optimized core architectures enabling new levels of performance and reliability.