A Carbon Fiber Composite Bidirectional Self‐Locking Structure Inspired by Chinese Mortise‐and‐Tenon Craftsmanship

ABSTRACT Self‐locking structures enable reversible assembly, yet most reported concepts provide locking in only one direction and are seldom implemented in fiber‐reinforced composites. Inspired by traditional Chinese mortise‐and‐tenon craftsmanship, we design and fabricate an I‐beam‐like bidirectional self‐locking structure (IBSS) in carbon fiber‐reinforced polymer composites. Cyclic loading and quasi‐static compression tests on single cells (SCs) and assembled IBSS are performed to assess direction‐dependent deformation, stiffness evolution, and energy absorption and to quantify the influence of wall thickness. X loading exhibits stronger recovery in cyclic response, whereas Y loading achieves higher specific stiffness and more stable force transmission. These differences are associated with the evolution of effective boundary constraint and contact engagement during interlocking. Increasing wall thickness enhances bending stiffness and contact confinement, shifts the onset and localization of buckling, and reshapes plateau development and energy dissipation. Finite element simulations based on laminate mechanics further reveal that ply angle and cell order control anisotropic stiffness, contact path, and collapse propagation, enabling direction‐specific design optimization for lightweight load‐bearing and energy‐absorbing applications.