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Master's Dissertation
DOI
10.11606/D.3.2009.tde-13102009-151346
Document
Author
Full name
Marcos Alves Rabelo
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2009
Supervisor
Committee
Pesce, Celso Pupo (President)
Martins, Clóvis de Arruda
Vaz, Murilo Augusto
Title in Portuguese
Estudo experimental do comportamento estrutural de barras curvas.
Keywords in Portuguese
Barras
Estabilidade
Estruturas (comportamento estrutural)
Flambagem
Abstract in Portuguese
A presente dissertação trata do estudo experimental do comportamento estrutural de barras helicoidais assentadas sobre superfície cilíndrica e sujeitas a cargas de compressão. Aparato experimental específico foi projetado e construído para este fim. O projeto, bem como a aferição deste aparato, é descrito em detalhes. Este aparato permite ajustar as barras através de um sistema de apoios constituídos por uma série de rolamentos, que podem ser posicionados de forma a conferir liberdade de deslocamento à barra em duas direções distintas: radial (normal à superfície cilíndrica de assentamento) e lateral (tangencial; bi-normal). A aplicação de carga compressiva se faz na direção tangencial à hélice não-deformada. Barras com seção transversal circular e retangular, com diversos comprimentos livres de flambagem e para diferentes ângulos de assentamento, foram ensaiadas. Estudos preliminares, com barras retas, permitiram avaliar as condições efetivas de engastamento proporcionadas pelo aparato. Nestes casos foi possível induzir o fenômeno de flambagem, recuperando-se, consistentemente, os valores de cargas críticas previstas pela teoria de Euler e avaliando-se o grau de engastamento proporcionado pelo aparato experimental. Filmagem com câmera de alta velocidade permitiu observar o fenômeno de instabilidade. O comportamento estrutural das barras curvas, de seção circular e retangular, foi então estudado. Tanto o comprimento livre quanto o ângulo de assentamento foi variado. O estudo permitiu levantar base de dados experimentais do comportamento de barras helicoidais nessas condições de carregamento e de condições de contorno. No entanto, para nenhuma das diversas condições ensaiadas foi possível induzir o fenômeno de instabilidade. Tal fato poderia dar subsídios a inferências acerca do estudo da instabilidade de tubos flexíveis do tipo birdcaging.
Title in English
Experimental study of structural behavior of curved bars.
Keywords in English
Bending
Buckling
Helix
Instability
Stability
Structural behaviour
Structures
Torsion
Abstract in English
This dissertation deals with an experimental study on the structural behavior of bars supported on a helical cylindrical surface and subject to compressive loads. A special experimental apparatus was designed and built for this purpose. The design, as well as the adjustment of such an apparatus is described in details. The device allows one adjusting the bars by using a system consisting of a series of bearings that can be positioned to give freedom to the structure in two different directions: radial (normal to the cylindrical surface) and lateral (tangential or bi-normal). The compressive load is applied in the tangential direction of the helix. Bars with circular and rectangular cross sections, with various buckling lengths and different helix angles, were tested. Preliminary studies with straight bars, have allowed to evaluate the boundary conditions offered by the apparatus. In these cases, it was possible to induce the phenomenon of buckling, obtaining, consistently, the values of critical loads provided by the theory of Euler and to evaluate the boundary conditions provided by the apparatus. The use of a high-speed camera allowed to observe the phenomenon of instability. The structural behavior of curved bars of circular and rectangular sections was also studied. Both, the test free length as the helix angle were varied. The study enabled us to get a huge amount of experimental data about the behavior of helical bars, subjected such loading and boundary conditions. However, the phenomenon of instability could not be induced, for any condition tested. This fact could collaborate for further inferences about the study of the birdcaging instability at flexible pipes.
 
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Publishing Date
2010-05-20
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • RABELO, Marcos A., PESCE, Celso P., and FUJARRA, André L.C.. An experimental investigation on the static structural behavior of helical bars. In Solid Mechanics in Brazil (Mecsol), Florianópolis, 2011. RJ : ABCM, 2011. vol. 1, p. 477-488.
  • RABELO, Marcos, Pesce, Celso P., and FUJARRA, André Luís Condino. An experimental investigation on the static structural behavior of helical bars. In Mecsol 2011, Florianópolis, 2011. Solid Mechanics in Brazil 2011.RJ : ABCM, 2011.
All rights of the thesis/dissertation are from the authors
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