Influence of Contact Geometry and Interface Mechanics on the Compressive Behavior of Self‐Locking Honeycomb Structures

Topologically interlocked materials preserve structural integrity through geometric constraint rather than traditional joints or adhesives, where each modular cell engages with its neighbors. This study investigates the compressive response of five self‐locking arc‐curved honeycombs fabricated by multijet fusion 3D printing, with varied contact‐surface geometries: simple single‐curved (SSC), cut single‐curved (CSC), simple double‐curved (SDC), and two lattice‐reinforced variants (SSC‐Lattice and CSC‐Lattice). Quasistatic compression tests were complemented by explicit finite element simulations incorporating a cohesive‐zone interface to capture friction, bonding, and progressive debonding. Among the unreinforced designs, SDC exhibits the highest initial stiffness and peak load, whereas CSC provides the highest SEA due to its more compliant and stable collapse behavior. Introducing internal lattice reinforcement enhances performance, doubling the initial stiffness and peak strength, and achieves the highest SEA (≈0.37 J/g). However, reinforcement reduces plateau stability and deformation stroke through earlier densification and abrupt postpeak load drops. Overall, the results demonstrate that tailoring contact curvature and interfacial mechanics provides a powerful strategy for balancing stiffness, peak strength, and crashworthiness in architected cellular materials. The optimized geometries exhibit high‐energy absorption efficiency and robust post‐yield behavior, highlighting their potential for lightweight impact‐mitigation and crashworthy structural systems.