EM - Escola de Minas

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6

Notícias

A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.

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Filtros

2019 - 201912020 - 20211

Configurações

Autor: search.filters.author.Gonçalves, Paulo BatistaAssunto: search.filters.subject.Bistable structures

Resultados da Pesquisa

Agora exibindo 1 - 2 de 2
  • Nenhuma Miniatura Disponível
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    Closed-form solutions for the symmetric nonlinear free oscillations of pyramidal trusses.
    (2021) Santana, Murillo Vinícius Bento; Gonçalves, Paulo Batista; Silveira, Ricardo Azoubel da Mota
    This work presents the development of analytical solutions regarding the symmetric free vibrations of pyramidal trusses, considering a general large strain measure. In this case, the undeformed and deformed configurations of the continuum are significantly different, requiring a clear distinction between them. Illustrative examples considering the quadratic (Green–Lagrange) and logarithmic (Hencky) strain measures are used to exemplify the influence of the strain measure on the results. Pyramidal trusses are well-known bistable structures and in the unloaded configurations may present different analytical solutions depending on the initial conditions: small amplitude vibrations around each stable equilibrium configuration or large cross-well vibrations. These families of solution are separated by two homoclinic orbits, constituting the boundaries of the two potential wells, which are related to the saddle point initial conditions. In addition, closed-form time solutions for the undamped vibrations are derived and the nonlinear frequency–amplitude relations, which are a measure of the degree and type of nonlinearity (hardening or softening), are obtained. Finally, a semi-analytical procedure for the damped vibrations is also constructed.
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    Stability and load capacity of an elasto-plastic pyramidal truss.
    (2019) Santana, Murillo Vinícius Bento; Gonçalves, Paulo Batista; Silveira, Ricardo Azoubel da Mota
    The present work investigates, using a corotational finite element formulation considering large displacements and rotations, geometric imperfections and an elasto-plastic material constitutive law, the nonlinear behavior of a pyramidal space truss under vertical and horizontal loads. Additionally novel analytical closed-form solutions for the nonlinear equilibrium paths, natural frequencies and critical parameters are derived for comparison purposes and investigation of the influence of geometric and material parameters on the truss stability. This geometry has an immediate practical interest since these structures are currently used in many present-day applications, either as main structural component or as a constitutive element. Four types of nonlinear instability phenomena are investigated theoretically and numerically: saddle-node (limit point) bifurcation, pitchfork bifurcation, individual Eulerian bars buckling and elasto-plastic buckling. Through a detailed parametric analysis the interaction between these buckling phenomena, using the FE tool, is investigated. In addition, the effect of elastic supports is considered. The influence of these phenomena on the load carrying capacity of the structure and its imperfection sensitivity is duly discussed in the present work. Finally, a detailed parametric analysis of a large roof composed of pyramidal truss units is conducted and the influence of the geometric parameters on its bistable behavior and load carrying capacity is investigated.