Stabilitet af tynde skalkonstruktioner

Bjarke Laustsen

Research output: Book/ReportPh.D. thesis

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Abstract

This thesis deals with the stability theory and its application on thin imperfect shell structures. Thin and slender structures are often used in modern load-bearing structures where the common material is a metal, particularly steel or aluminum. This thesis only deals with stability theory for conservative systems.
Stability theory is by many structural engineers considered a difficult and complicated subject. Therefore in this thesis a simple and systematic method has been developed which only requires knowledge on tensor analysis and elementary calculus of variations.
In the first part of the thesis the new theory has been used to develop a theory of stability. The equilibrium system, the stability of which is considered, may often be investigated by a linear theory. In this the effect of shear forces in the direction of the shell normal are neglected and equilibrium is formulated in the undeformed configuration. The classical theory of stability evolves by formulating equilibrium conditions for adjacent configurations. These are created by means of a first variation of the position vector.
The present theory requires, as all shell theories, a number of assumptions and simplifications in order to obtain a kind of clearness. By using calculus of variations one has the advantage that only those terms which are important appear in the equations. Thus one does not need to estimate the important parameters and those unimportant.
In the first part also an approximate non-linear theory is formulated. This theory may also take into account imperfections.
In the second part of the thesis the new theory is used in a calculation of a circular cylindrical shell axially loaded. The numerical solution is carried out by means of difference equations. The eigen-value problem is solved and furthermore two kinds of imperfections and their influence on the load-carrying capacity are analyzed.
Original languageDanish
PublisherTechnical University of Denmark, Department of Civil Engineering
Number of pages164
ISBN (Print)9788778774385
Publication statusPublished - 2016
SeriesB Y G D T U. Rapport
NumberR-348
ISSN1601-2917

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