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CivilComp Proceedings
ISSN 17593433 CCP: 93
PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by:
Paper 199
High Accuracy Postbuckling Analysis of Box Section Struts using Three Different Versions of Finite Strip Method S.A.M. Ghannadpour^{1}, H.R. Ovesy^{2} and M. Nassirnia^{2}
^{1}Aerospace Engineering Department, Faculty of New Technologies, Shahid Beheshti University, G.C., Tehran, Iran
S.A.M. Ghannadpour, H.R. Ovesy, M. Nassirnia, "High Accuracy Postbuckling Analysis of Box Section Struts using Three Different Versions of Finite Strip Method", in , (Editors), "Proceedings of the Tenth International Conference on Computational Structures Technology", CivilComp Press, Stirlingshire, UK, Paper 199, 2010. doi:10.4203/ccp.93.199
Keywords: postbuckling, finite strip, fullanalytical, semienergy, semianalytical, vonKarman equations.
Summary
Prismatic plates and plate structures are increasingly used as structural components in various branches of engineering, chief of which are aerospace and marine engineering. These structures are often employed in situations where they are subjected to inplane compressive loading. In aerospace, in particular, the quest for efficient, lightweight structures often leads to allowing for the possibility of local buckling and postlocalbuckling at design load levels. Thus it is important to accurately predict the buckling and post buckling behavior of such structures. More recently, Ghannadpour and Ovesy [1,2,3,4] have developed a fullanalytical postlocalbuckling finite strip method (FSM) in which the solution of the vonKarman's equilibrium equation was substituted into the vonKarman's compatibility equation. It is noted that in their analysis, only one of the calculated outofplane buckling deflection modes, corresponding to the lowest buckling load, i.e. the first mode is used for the initial postbuckling study. For this reason, their method was designated by the name singleterm fullanalytical finite strip method (Fa FSM). It is worth mentioning that the singleterm assumption within Fa FSM analysis corresponds to the fact that the shape of the plate in the postbuckling region is unchangeable in both longitudinal and transverse directions. Thus, the relationship between load and endshortening becomes a linear function.
In the current paper, the theoretical developments of a high accuracy multiterm Fa FSM for the postbuckling analyses of isotropic box section struts are attempted. The strip is developed based on the concept that it is effectively a plate, and thus the vonKarman's equilibrium equation is solved exactly to obtain the buckling loads and the corresponding forms of outofplane buckling deflection modes. In order to solve the vonKarman's compatibility equation, the deflected form after the buckling is assumed as a combination of first, second and higher (if required) modes of buckling. Subsequently, the general form of inplane displacement fields in a postbuckling region can be obtained. This method is characterized by the use of buckling mode shapes, obtained from the vonKarman's equilibrium equation, as global shape functions for representing displacements in a geometrically nonlinear analysis. The method developed is subsequently applied to analyze with high accuracy the postbuckling behaviour of isotropic box section struts for which the results were also available through the application of the semienergy finite strip and semianalytical finite strip methods. Through the comparison of the results and the appropriate discussion, the knowledge of the level of capability of these methods is significantly developed. References
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