Development and performance analysis of boundary-reinforced carbon fiber-based buoyancy structures

The current rescue depth for sea operations is typically limited to 450 meters, as efforts beyond this depth are generally considered impractical. Buoyancy materials, which occupy the largest volume in deep-submergence rescue vehicles, play a critical role in providing flotation and influencing the vehicles' operational endurance. In this study, a lightweight and high-strength carbon fiber-based buoyancy structure (CFBS) was developed to enhance the pressure resistance of underwater vehicles in rescue systems. The stress distribution and failure modes of the CFBS under hydrostatic pressure were systematically analyzed, with experimental results showing strong agreement with numerical simulations. Compared to CFBSs with uniform wall thickness, the boundary-reinforced design demonstrated a 57.67 % improvement in hydrostatic pressure resistance at comparable densities. The fabricated small-scale structural component demonstrated a density of 0.392 g/cm³ and a hydrostatic pressure strength of 17.99 MPa, while the large-scale structural component exhibited a density of 0.296 g/cm³ and a hydrostatic pressure strength of 12 MPa, outperforming other buoyancy materials of similar class. These findings provide a robust foundation for advancing composite material technologies in underwater applications.