Orthogonal stepped-chiral metamaterial for load-bearing morphing skins: Topology-regulated mechanical response and deformation performance

Load-bearing morphing skins in advanced aerospace vehicles must sustain aerodynamic loads while undergoing substantial in-plane deformation, posing a persistent stiffness–compliance conflict. To address this challenge, this study proposes an orthogonal stepped-chiral (OSC) metamaterial architecture based on a dual-orthogonality design principle. By integrating global and local orthogonal geometries, the proposed structure decouples load-bearing and deformation pathways, thereby activating a stable quasi-pure-bending–dominated mechanism that enhances deformation efficiency while suppressing geometric hardening. A topology-regulated configuration strategy enabled by chiral symmetry modulation allows three distinct array arrangements—regular, hybrid, and staggered—to achieve tensile–shear coupling, quasi-zero Poisson’s ratio behavior, and stiffness-enhanced zero Poisson’s ratio responses within a unified architecture. Theoretical analysis and numerical simulations show that the OSC structure reduces the effective modulus along the morphing direction by 68% compared with accordion honeycombs and lowers the actuation force by a factor of 16 relative to tetrachiral lattices at 10% strain under the equal-envelope/equal-wall-thickness benchmark. Experiments and prototype demonstrations further confirm stable morphing-oriented deformation within the investigated range.