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Title: Near-coincident doubly-symmetric branching systems : elastic post-buckling behaviour and imperfection sensitivity
Author: Johnson, Barbara Helen
ISNI:       0000 0001 3591 0125
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1990
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A neai-coincident doubly-symmetric branching system is first considered in general terms. The form and stability of the equilibrium paths of the ideal system are studied. In the presence of two major imperfections the system exhibits a preferred mode of buckling corresponding to the least-stiff uncoupled path of the ideal system. A classification of the system is made based on the stability of the bifurcation point when imperfections purely in the form of the most-stiff buckled mode and solely in the form of the least-stiff buckled mode are applied. This general theory is then applied to three theoretical models and the imperfection sensitivity surfaces of their natural equilibrium paths are generated. The first model is a strut on a Winkler type foundation. An investigation of the effect of variations of energy coefficients, splitting parameter and imperfections leads to the four general forms of stability boundaries proposed. According to the form of the stability boundary a system will behave statically, partially dynamically or dynamically for all combinations of the two imperfections. The second is a modified Stein model which is analogous tothin rectangular plates under in-plane compression and the third is a simply-supported rectangular plate, laterally restrained, under uniaxial compression. Finally a series of experiments, conducted to verify qualitatively the simple theories proposed, are described. Rectangular steel plates were held in a semi-rigid test frame which provided simple support to all edges while restraining the unloaded edges from lateral movement. A number of out-of-plane point loads were used to represent the imperfections. Uniaxial compression was applied to the plates and Fourier analyses carried out on the out-of-plane displacements of the longitudinal centreline provided the interaction between the component modes of deflection, in particular the predicted coupling between the one- and two-halfwave deflected forms.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Structures' buckling analysis