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Stability of statically and periodically loaded structures

Svensson, Ingrid LU (2000)
Abstract (Swedish)
Popular Abstract in Swedish

I denna avhandling analyseras olika typer av stabilitets fenomen. Först studeras det kvasi-statiska uppförandet av en elastisk struktur som lastas med en växande last. Beteenden vid laster som är högre än bucklingslasten studeras med en vägföljande metod där gränspunkter (limit-points) och bifurkationspunkter kan bestämmas med god noggrannhet och jämviktslösningarna kan föjas ut på de sekundära grenarna.



Därefter analyseras en axiellt lastad balk, både när dess transversella utslag begränsas och när den kan röra sig fritt. Balken lastas periodiskt och de dynamiska effekterna, inklusive dämpning, tages med i analysen. Stabilitets områden i lastparameterrummet bestäms via Floquet... (More)
Popular Abstract in Swedish

I denna avhandling analyseras olika typer av stabilitets fenomen. Först studeras det kvasi-statiska uppförandet av en elastisk struktur som lastas med en växande last. Beteenden vid laster som är högre än bucklingslasten studeras med en vägföljande metod där gränspunkter (limit-points) och bifurkationspunkter kan bestämmas med god noggrannhet och jämviktslösningarna kan föjas ut på de sekundära grenarna.



Därefter analyseras en axiellt lastad balk, både när dess transversella utslag begränsas och när den kan röra sig fritt. Balken lastas periodiskt och de dynamiska effekterna, inklusive dämpning, tages med i analysen. Stabilitets områden i lastparameterrummet bestäms via Floquet teori och finita elementformulering för den fria balken och verifieras experimentellt.



Det begänsade systemet visar sig vara mycket känsligt för begynnelsevärden och kaotiska rörelser detekteras både numeriskt och i experiment. Modelleringen av islagen och dämpning visar sig vara kritiskt och stort arbete läggs på att utveckla numeriska modeller som ger god överensstämmelse mellan experiment och beräkningar. (Less)
Abstract
In this thesis different kinds of stability phenomena are analysed. Firstly the quasi-static behaviour of an elastic structure is studied for increasing loading. The post-buckling behaviour is studied numerically with a path-following method where limit points and bifurcation points can be determined with good accuracy and the solutions may be followed out on the secondary branches. Secondly, an axially loaded beam, both when the deflection is unconstrained and when the transversal motion is limited by constraints. The beam is periodically loaded and the dynamic effects as well as the damping effects are taken into account for the analysis. The regions of stability in the loading parameter space are determined using Floquet theory and a... (More)
In this thesis different kinds of stability phenomena are analysed. Firstly the quasi-static behaviour of an elastic structure is studied for increasing loading. The post-buckling behaviour is studied numerically with a path-following method where limit points and bifurcation points can be determined with good accuracy and the solutions may be followed out on the secondary branches. Secondly, an axially loaded beam, both when the deflection is unconstrained and when the transversal motion is limited by constraints. The beam is periodically loaded and the dynamic effects as well as the damping effects are taken into account for the analysis. The regions of stability in the loading parameter space are determined using Floquet theory and a finite element formulation for the unconstrained beam and this is verified experimentally.



The constrained system turns out to be very sensitive of initial conditions and chaotic motions are detected both in the numerical simulations and in the experiments. The modelling of the impacts and damping effects turns out to be crucial and great effort is made for developing numerical models where a good correspondence between experiments and computations is reached. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Ståhle, Per, Solid Mechanics, Malmö University,205 06 Malmö
organization
publishing date
type
Thesis
publication status
published
subject
keywords
hydraulics, Mechanical engineering, Produktionsteknik, Production technology, experiments, damping, impacts, branch switching, dynamic stability, deflation, path following, vibrationer, akustik, vakuumteknik, hydraulik, Maskinteknik, vibration and acoustic engineering, vacuum technology
pages
95 pages
publisher
Div. of Solid Mechanics, Box 118, S-221 00 Lund,
defense location
M:E, M-huset, Ole Römers väg 1, Lund
defense date
2000-11-17 10:15
external identifiers
  • Other:LUTFD
ISBN
91-7874-093-2
language
English
LU publication?
yes
id
014381e6-1f55-4dcb-907d-2d7d53734bed (old id 40985)
date added to LUP
2007-08-01 12:27:02
date last changed
2016-09-19 08:45:03
@misc{014381e6-1f55-4dcb-907d-2d7d53734bed,
  abstract     = {In this thesis different kinds of stability phenomena are analysed. Firstly the quasi-static behaviour of an elastic structure is studied for increasing loading. The post-buckling behaviour is studied numerically with a path-following method where limit points and bifurcation points can be determined with good accuracy and the solutions may be followed out on the secondary branches. Secondly, an axially loaded beam, both when the deflection is unconstrained and when the transversal motion is limited by constraints. The beam is periodically loaded and the dynamic effects as well as the damping effects are taken into account for the analysis. The regions of stability in the loading parameter space are determined using Floquet theory and a finite element formulation for the unconstrained beam and this is verified experimentally.<br/><br>
<br/><br>
The constrained system turns out to be very sensitive of initial conditions and chaotic motions are detected both in the numerical simulations and in the experiments. The modelling of the impacts and damping effects turns out to be crucial and great effort is made for developing numerical models where a good correspondence between experiments and computations is reached.},
  author       = {Svensson, Ingrid},
  isbn         = {91-7874-093-2},
  keyword      = {hydraulics,Mechanical engineering,Produktionsteknik,Production technology,experiments,damping,impacts,branch switching,dynamic stability,deflation,path following,vibrationer,akustik,vakuumteknik,hydraulik,Maskinteknik,vibration and acoustic engineering,vacuum technology},
  language     = {eng},
  pages        = {95},
  publisher    = {ARRAY(0x8e0dd38)},
  title        = {Stability of statically and periodically loaded structures},
  year         = {2000},
}