Buckling of a hollow double-folded sandwich pressure shell under hydrostatic external pressure

Based on the principle of origami engineering, a carbon fiber-reinforced polymer (CFRP) pressure shell with a hollow double-folded sandwich structure was designed to enhance its buckling under hydrostatic external pressure. The structure integrates a checkerboard-patterned hollow core with localized folding units, combining a lightweight PVC core and high-strength CFRP skins to maximize the sectional moment of inertia while minimizing mass. This configuration capitalizes on the multi-stability and energy-absorption advantages inherent to origami-inspired geometries. The ultimate buckling load was investigated through nonlinear numerical analysis and hydrostatic pressure tests. Results demonstrate that the shell buckled symmetrically along its central axis, with experimental data showing high repeatability. Nonlinear simulations agreed with experimental values within a 10 % margin. Crucially, the origami-engineered shell exhibited a significantly higher buckling load than a traditional double-layer shell of equivalent mass, confirming the efficacy of the sandwich architecture in boosting structural stability.