Development of Temporary Deployable Structures

Abstract

Deployable structure is any structure which from a stowed and closed configuration deploys into a fully or partially functional structure. The interest of research in this area has been booming since the late 20th century to the early 21st century. The idea of having a deployable structure originated from the space race of the mid-20th century. The structures which need to be deployed in space should have low payload and should occupy little space during transportation. The idea which then was carried forward in many applications like retractable roof systems, tent structures, masts etc. The design of deployable structure is a constant jugglery between the concept of functionality and deployability. The research shows that either one of them is compromised. The current study aims at exploring various deployable structural mechanisms available. This involves an intensive literature survey in the field of deployable structures and also origami engineering. The study explores most of the mechanisms available for deployable structures which broadly include rigid origami patterns, polyhedral connectors, Overconstrained Mechanisms and Scissor-like elements. These mechanisms have been studied in depth to determine their efficacy for use in deployable structures. Another objective of this study is to develop a deployable temporary tent structure which can be used to shelter the Light Combat Helicopter developed by Hindustan Aeronautics Limited. For this as well, an exhaustive literature survey is conducted for the currently available temporary, deployable or temporary and deployable tent and mast structures. Following which, Bennett Mechanism had been chosen to be the basic structural mechanism to develop the tent structure. The final dimensions of the structure analysed are 16.94m (L) x 11.09m x 6.39m (H). From the literature of long-span Bennett Structures, it has been learnt that the deflection in the temporary deployable tent structure using the Bennett Mechanism increases for low-weight structures. An attempt is made to introduce scissor-like elements like the polar linkages along with Bennett barrel vaults to reduce deflections. This has also been done by trying two different sets of polar linkages. All these models have been analysed in the commercial STAAD.Pro v8i. The load analysis has been done as per the relevant Indian Standard Codes. As the focus is on the serviceability criteria, the load cases that are used are DL + 0.5SL and DL+SL. A total of 15 models for 5 assemblies have been analysed to prove the hypothesis. From these 5 assemblies, 4 have been taken from previous literature and one has been designed during the course of this project. The results show that the proposed geometry works effectively for reducing the deflection of the structure across all assemblies. The geometry designed during the course of this project works efficiently in drastically reducing the deflections.