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Title: Large deflection phenomena in cylindrical shells
Author: Holst, J. M. F. G.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1996
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In the past, much research effort has been directed towards the problem of buckling of thin cylindrical shell structures under axial loading. Thus far, however, no wholly satisfactory solutions have been attained. In this thesis a new approach to shell buckling is proposed. It is suggested that a careful examination of a heavily deformed shell structure in the post-buckling regime - and the processes leading up to this state of deformation - may clarify some of the principles involved in its loss of stability. The complex deformation patterns can be reduced to a more elementary description consisting of inextensional and transitional regions. Corresponding features are found in shell inversions; and in this dissertation two relatively simple examples of inversion under a radial load are studied. Experiments investigating the inversion of a cylindrical shell under a radial point load are reported. Some straightforward empirical formulae are obtained that well describe the characteristics of the deformed geometry; and the applied load is established as a function of the deformation. The inversion of a spherical shell under a radial point load is considered as means of examining some of the basic features observed in the experiments performed, whilst eliminating the complexities arising from the lack of symmetry in the cylindrical case. A "simple model" is detailed which clearly highlights the major components of the total strain energy of the deformed surface and their origin. The results from this model are confirmed using a finite-element analysis, which also provides a more comprehensive description of the overall stress state of the shell. The finite-element method is likewise applied to the case of the cylindrical shell as an extension of the experiments. Findings from the latter are employed to confirm the validity of the numerical analysis. A detailed account is given of the distribution of stresses and strains over the deformed surface; and the similarities with the case of the spherical shell are outlined. Finally, an analytical model is established for the case of the cylindrical shell using the empirical formulae. The derivation of a condensed expression for the total strain energy is presented. It is shown that the model represents well the relevant data obtained numerically.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available