Analysis of deployable structural elements for space applications

In this work a series of analysis concerning the behaviour of structures typically used in space applications are carried out. These structures are united by their properties of lightweight and very low thickness, along with the need for them to occupy an highly confined space; this last necessity makes the deployable structures the most acceptable solutions in the space industry. The numerical analysis of this kind of structures are carried out by means of two different codes: the commercial software Abaqus, and the Mul2 code developed by the homonymous group of the PoliTo, based on the CUF theory. The objective of this work is therefore to introduce the main features of the deployable structures, and then to demonstrate the ability of the Mul2 code to reproduce very reliable results for different kind of analysis and structures. The thesis is subdivided into two distinct parts, consisting in two chapters each, presenting separately the theoretical subject on which the Mul2 code is based, and the numerical analysis themselves. Chapter 1 is an introduction on the main subject: deployable structures. The existing literature on the argument is presented, together with some classification methods. Moreover, some relevant and commonly used space structures are showed, and both their folding processes and their applications are given. In Chapter 2 the CUF theory is briefly introduced, just enough to understand the mathematics standing hidden behind the code. The application of the CUF theory to non-linear analysis is presented too. Chapter 3 deals with the preliminary analysis of some classical structures, not necessarily applicable for spatial purposes: in ascending order of complexity are analysed square beams, C-beams, and C-beams with holes along the axis. Finally in Chapter 4 typical space structures such as tape springs are analysed, studying also the effect of some features on the buckling behaviour. In the end of the chapter the numerical results are also compared with an experimental test carried out by the CalTech. In the Conclusions are provided some general comments regarding the analysis previously made, and some ideas for future developments.