A penalty approach to obtain lower bound buckling loads of imperfection-sensitive shells
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Date
2015Author
Godoy, Luis A.
Jaca, Rossana C.
Sosa, Eduardo M.
Flores, Fernando G.
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The strategy of Reduced Stiffness (or Reduced Energy) Analysis, in which selected energy components are
eliminated to account for mode interaction and imperfection-sensitivity in a simplified way, was developed by Croll and co-workers since the early 1980s. This physical interpretation allows the formulation as an eigenvalue problem, in which the eigenvalue (critical load) is a lower bound to experiments and to nonlinear incremental analysis. This paper considers the computational implementation of
both reduced stiffness and reduced energy approaches to the buckling of shell structures by means of
perturbation techniques and penalty parameter methods. The structural configurations of interest in this
work are cylindrical shells with or without a roof. The reduced stiffness approach has been implemented
in a special purpose finite element code for shells of revolution, whereas the reduced energy methodology was implemented in a general purpose finite element code. The present results are compared
with geometrically nonlinear analysis including geometric imperfections. Achievements and difficulties
in extending the methodologies to complex problems in engineering practice are highlighted.