Energy-absorbing sandwich structures must sustain large deformation yet transmit minimal stress to the protected system, achieving both material efficiency and structural performance. This paper investigated the energy absorption of a composite sandwich foldcore consisting of a curved-straight hybrid-crease origami paperboard. The hybrid-crease pattern consists of two Miura cells with identical trapezoidal panels connected to two lens-shaped curved creases. Experiments and finite-element simulations show a structural toughness enhancement up to 36% relative to its straight-crease counterpart without increasing yield strength. A parametric analysis over a wide range of geometric parameters with an anisotropic elastic-plastic material model and rotational hinge elements reveals that geometric frustration at conical apices induces periodic imperfections, triggering synchronized local plastic buckling. The mechanism unveiled here generates a secondary load peak driven by localized densification at the buckled zones. In tightly packed arrays, interactions among curved panels promote global buckling that delays densification and increases energy absorption. Together, the multiscale buckling mechanism raises both the specific energy absorption and mechanical efficiency beyond those of conventional prismatic sandwich foldcores. The results also show the volumetric energy absorption of these paper-based foldcores rivals that of aluminum honeycombs and low-density metal foams of equivalent mass. The findings establish curved-crease-induced buckling as a distinct geometric pathway for designing high-performance, thin-walled composite energy absorbers. • Quasi-static compression response of lockable hybrid-crease composite foldcores • Hybrid-crease foldcores have superior energy absorption than straight-crease cores • Force-displacement response shows a secondary peak and delayed densification • Secondary peak stems from periodic imperfections produced by geometric frustration • Paperboard foldcores match energy absorption of conventional aluminum/metal cores
Mirzajanzadeh et al. (Sun,) studied this question.