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Space webs
KTH, School of Engineering Sciences (SCI), Mechanics.
KTH, School of Engineering Sciences (SCI), Mechanics.ORCID iD: 0000-0001-6802-8331
2006 (English)Report (Other academic)
Abstract [en]

This report presents a study of the controlled deployment of a large web in space. The study is composed of three major parts:1. The design of the space web starts with a study of different geometries, i.e. threeor four corners. For each geometry, three different mesh topologies are investigated,i.e. triangular, square or hexagonal meshes. An analysis by the force method showedt hat only the web with a square mesh could be prestressed by a centrifugal forcefield. The triangular mesh had a too high degree of static indeterminacy, whichresulted in compressed elements. The hexagonal mesh had a too high degree ofkinematic indeterminacy and became too distorted under the centrifugal force field.The square mesh webs were subsequently analysed in terms of out-of-plane flexibilityand vibrational characteristics. Preliminary investigations on the choice of materialfor the web and the probability of web failure due to micro-meteoroid impact werealso performed. MATLAB routines that automatically generates the web with anarbitrary size, mesh width and sag-to-span ratio have been developed.2. A successful deployment requires an adequate folding pattern. A literature review identified the star-like folding pattern as a promising candidate. The folding is performedin two distinctive stages. First, the web is folded towards the central hub in a way so that three or four radial arms are formed, depending on the chosen geometry.Then, the radial arms can be either coiled around the central hub or folded ina zig-zag manner towards the hub. The MATLAB-generated web from part 1 is fed into new MATLAB routines, which folds the web according to the various pattern described above.3. The dynamic deployment of the space web is analysed by a two-dimensional analyticalmodel in MATLAB and a full three-dimensional model by the commercialfinite element software LS-DYNA. The developed analytical models can simulatethe deployment of the arms from a position coiled around the hub or reeled up onspools. A simple control strategy was found in literature and implemented in the analyticalmodel with successful results. The MATLAB-generated model of the foldedweb was inserted into the software LS-DYNA. For an uncontrolled deployment, thefinite element model yields the expected coiling off-coiling on oscillating behaviour.The control law with the drooping characteristics is not implemented in the finite element model, but analyses with a simplified control law shows good agreement between the analytical and the finite element results for the deployment of the stararms.

Place, publisher, year, edition, pages
2006. , viii, 86 p.
National Category
Other Materials Engineering
URN: urn:nbn:se:kth:diva-25945OAI: diva2:361046
QC 20101108Available from: 2010-11-08 Created: 2010-11-08Bibliographically approved

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Gärdsback, MattiasTibert, Gunnar
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