The self-locking structure achieves interlocking property through ingenious design of the connection mode between cells, which enables the cells to lock with each other without the need for any additional constraints. The self-locking structure possesses significant advantages, such as light weight, portability, rapid assembly, and disassembly. Therefore, this structure is widely applied in various fields, such as shock resistance and explosion prevention. Self-locking structures exist in many structures in nature. The design concepts of self-locking structures are introduced from three aspects: the inspiration from biomimetic self-locking structures, the energy absorption mechanism of periodic structures, and failure of shear bands in periodic structures. The research progress of two-dimensional unidirectional self-locking structures, three-dimensional multi-directional self-locking structures and curved self-locking structures are then respectively introduced based on the classification of self-locking direction. Among them, the multi-directional self-locking structure withstands more complex loading conditions. Therefore, research progress of three representative multi-directional self-locking structures based on dumbbell-type, bone stitching, and origami design are further introduced. Finally, the research on the self-locking structure is summarized, and its future research prospects are discussed.

Lightweight high-strength composite lattice stiffenedshell structureis widely used in aerospace due to its unique advantages of high specific strength, high specific stiffness and strong design ability. The preparation process involves various techniques such as fiber winding, molding, and locking, ensuring precision and stability in the structures. This paper outlines the preparation techniques and mechanical performance characterization methods, encompassing static failure modes, ultimate loads, and dynamic modal shape analysis. Furthermore, it provides a comprehensive review of the latest research advancements in the multi-functionalization of composite materials in the aerospace field, and offers insights into the future development trends, to provide valuable references for research and applications in related domains.

Auxetic mechanical metamaterials are artificially architected materials that possess negative Poisson’s ratio, demonstrating transversal contracting deformation under external vertical compression loading. Their physical properties are mainly determined by spatial topological configurations. Traditionally, classical auxetic mechanical metamaterials exhibit relatively lower mechanical stiffness, compared to classic stretching dominated architectures. Nevertheless, in recent years, several novel auxetic mechanical metamaterials with high stiffness have been designed and proposed for energy absorption, load-bearing, and thermal-mechanical coupling applications. In this paper, mechanical design methods for designing auxetic structures with soft and stiff mechanical behavior are summarized and classified. For soft auxetic mechanical metamaterials, classic methods, such as using soft basic material, hierarchical design, tensile braided design, and curved ribs, are proposed. In comparison, for stiff auxetic mechanical metamaterials, design schemes, such as hard base material, hierarchical design, composite design, and adding additional load-bearing ribs, are proposed. Multi-functional applications of soft and stiff auxetic mechanical metamaterials are then reviewed. We hope this study could provide some guidelines for designing programmed auxetics with specified mechanical stiffness and deformation abilities according to demand.