Design Criteria for a novel self-locking mechanism for Deployable Structures

This dissertation considers the design of Deployable Structures: a type of engineering structures that can be packaged into a compact size for transportation or storage and expanded in the working structures at the time of operation. We focus on those made by bars connected by pin joints that can be expanded into a larger form in a continuous action due to the geometric inter‑linking of their components. The critical factor is for these structures to maintain stability since they behave like a mechanism. The present study presents a type in which the geometric arrangement of the bars enables it to be spontaneously stable at the expanded configuration. During the deployment an incompatibility between nodes distances and the length of the respective bars provokes a strain state in the structure that suddenly disappears when the structure is fully expanded, this process recalls the snap‑through phenomenon. It can be proved that the snap‑trough as effect of these structures depends on both geometry of the structure and flexibility of the bars, lesser flexible they are and more strong the snap‑through is, this latter case gives as result a structure pretty stable and stiff but not simple to fold and deploy. The final aim is to obtain a structure enough rigid to carry load and to be stable, but that can be easily fold and deploy, as made by flexible bars that are able to bend without breaking. Finally, for dealing with this issue the paper considers how Deployable Structures can be made stable by including a novel self‑locking mechanism in their design. The purpose improves the current design of these structures since neither bending in the bars nor snap‑through is required to maintain stability.