LAUSR

Abstract Self-locking foldable grid structures (FGSs) can be converted from a mechanical state to a structural state without the need to impose additional geometric constraints. However, the lack of a systematic understanding of the self-locking mechanism and the absence of a simple method to assess the self-locking capability have hindered further innovations and applications of such structures. In this paper, the geometric incompatibility function of structural units (SUs) was proposed by analyzing the mechanism motion of the two types of scissor-like elements (SLEs), thereby clarifying the self-locking mechanism of FGSs. Then, based on this function, the approximate expression for evaluating the self-locking capability of SUs was derived using the work-energy principle. This evaluation shows that the expression is concise in form and has a good application feasibility in the preliminary design phase. Furthermore, the results obtained by the expression show that the parameters t (thickness) and h (distance between the lower central node and the plane) have a critical influence on the self-locking performance compared to parameter L (side length), and the method of adjusting the h value can be preferentially adopted to control the self-locking capability of the entire structure. The research methods and results of this paper can provide a reference for structural designs and engineering applications of self-locking FGSs.