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Design and analysis of tensegrity power lines
KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.ORCID iD: 0000-0001-6802-8331
2012 (English)In: International Journal of Space Structures, ISSN 0956-0599, Vol. 27, no 2-3, 139-154 p.Article in journal (Refereed) Published
Abstract [en]

Overhead transmission power lines have undergone very small aesthetic and technical changes over time. Studies on mitigation of the electromagnetic field shows that utilizing a helix configuration is an effective way to reduce the electromagnetic field. This study proposes to use tensegrity structures as power lines. Tensegrity structures are composed of tension and compression elements in equilibrium. Modules, simple units with a certain rotation, are connected together to design of overhead power lines with considerable electromagnetic field reduction. A form-finding method enables the design of various free-form configurations. A parametric study is performed to investigate the influence of the module dimensions on the stiffness of the power line. A design algorithm was used for determining the optimum size of elements and the pre-stress level. The selected baseline structure was able to tolerate the wind and ice loads in severe conditions with a 50 times reduction in electromagnetic field. Finally a sensitivity analysis is performed to show the effects of element loss or damage.

Place, publisher, year, edition, pages
2012. Vol. 27, no 2-3, 139-154 p.
Keyword [en]
electromagnetic field, form-finding, parametric study, power lines, sensitivity analysis, tensegrity, wind and ice loads, Ice loads, Tensegrities, Design, Electromagnetic fields, Electric lines
National Category
Applied Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-100529DOI: 10.1260/0266-3511.27.2-3.139Scopus ID: 2-s2.0-84863517487OAI: oai:DiVA.org:kth-100529DiVA: diva2:543810
Note
QC 20120810Available from: 2012-08-10 Created: 2012-08-09 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Stiffness and vibration properties of slender tensegrity structures
Open this publication in new window or tab >>Stiffness and vibration properties of slender tensegrity structures
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The stiffness and frequency properties of tensegrity structures are functions of the pre-stress, topology, configuration, and axial stiffness of the elements. The tensegrity structures considered are tensegrity booms, tensegrity grids, and tensegrity power lines.

A study has been carried out on the pre-stress design. It includes (i) finding the most flexible directions for different pre-stress levels, (ii) finding the pre-stress pattern which maximizes the first natural frequency.

To find the optimum cross-section areas of the elements for triangular prism and Snelson tensegrity booms, an optimization approach is utilized. A constant mass criterion is considered and the genetic algorithm (GA) is used as the optimization method.

The stiffness of the triangular prism and Snelson tensegrity booms are modified by introducing actuators. An optimization approach by means of a GA is employed to find the placement of the actuators and their minimum length variations. The results show that the bending stiffness improves significantly, but still an active tensegrity boom is less stiff than a passive truss boom. The GA shows high accuracy in searching the non-structural space.

The tensegrity concept is employed to design a novel transmission power line .A tensegrity prism module is selected as the building block. A complete parametric study is performed to investigate the influence of several parameters such as number of modules and their dimensions on the stiffness and frequency of the structure. A general approach is suggested to design the structure considering wind and ice loads. The designed structure has more than 50 times reduction of the electromagnetic field and acceptable deflections under several loading combinations.

A study on the first natural frequencies of Snelson, prisms, Micheletti, Marcus and X-frame based tensegrity booms has been carried out. The result shows that the differences in the first natural frequencies of the truss and tensegrity booms are significant and not due to the number of mechanisms or pre-stress levels. The tensegritybooms of the type Snelson with 2 bars and prism with 3 bars have higher frequencies among tensegrity booms.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. vii, 25 p.
Keyword
Tensegrity booms, Tensegrity grids, Tensegrity power lines, Finite element analysis, Genetic algorithm, Flexibility analysis, Form-finding, Pre-stress design, Optimization
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-101769 (URN)978-91-7501-461-6 (ISBN)
Public defence
2012-09-20, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20120904

Available from: 2012-09-04 Created: 2012-09-03 Last updated: 2012-09-04Bibliographically approved

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Tibert, Gunnar

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