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Some Aspects of Wear and Structural Dynamics

Knudsen, Jakob LU (2005)
Abstract
The topic of this thesis is dynamics and



wear of structures. In the six appended papers different aspects of



wear and dynamics of a model system are studied. The considered



system consists of a long slender rod with unilateral supports,



subject to harmonic and stochastic excitation. The rod is held at



one end with stiff springs preventing translation and rotation and



constrained by loose supports near the other.



In the first two papers the vibration and impact dynamics of the



model system subject to periodic and stochastic forcing are



analysed. The wear work rates at... (More)
The topic of this thesis is dynamics and



wear of structures. In the six appended papers different aspects of



wear and dynamics of a model system are studied. The considered



system consists of a long slender rod with unilateral supports,



subject to harmonic and stochastic excitation. The rod is held at



one end with stiff springs preventing translation and rotation and



constrained by loose supports near the other.



In the first two papers the vibration and impact dynamics of the



model system subject to periodic and stochastic forcing are



analysed. The wear work rates at impact points are evaluated with or



without friction. Model computations are compared with measurements



of contact forces and displacements made on a loosely supported rod



with nuclear fuel dimensions. The comparison validates the modeling.



The first two papers also contain global bifurcation analysis of



idealized versions of the model system for both harmonic and



stochastic loading. Regions of periodic and stochastic response are



identified for the case of periodic forcing. The regions of stable



periodic response are subjected to stability and bifurcation



analyses in the third paper. The fourth paper focuses on the



transition from stable periodic to chaotic response and the



existence of stable multi periodic solutions within the chaotic



regime. The third paper also contains an evaluation of the wear work



rate along the identified stable paths of period one solutions. In



the fourth paper a wear law is introduced which enables life time



predictions of such stable solutions. The basin of attraction for a



stable solution is also discussed.



The sliding amplitude is usually in the fretting range for impacting



systems such as the model considered in this thesis. The fifth



paper deals with fretting wear maps to differentiate different



regimes of fretting contact. A systematic method to compare fretting



wear data from different sources with different contact geometries



is developed. The method is applied to experimental data and new



maps are presented in the form of dimensionless variables.



The last paper deals directly with breakdown of materials due to



wear induced loads. An idealized spring model is used to show that



breakdown of disordered media due to applied shear forces behaves



like a first order phase transition in condensed matter systems.



Finally, the burst size distribution during rupture is evaluated and



it is shown that the system behaves like the fiber bundle model with



global load sharing. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Hansen, Alex, Department of Physics, Norwegian University of Science and Technology, N-7034 Trondheim, NORWAY
organization
publishing date
type
Thesis
publication status
published
subject
keywords
vibration and acoustic engineering, Mechanical engineering, hydraulics, chaos, interfacial breakdown, stability, Maskinteknik, hydraulik, vakuumteknik, vibrationer, akustik, vacuum technology, fretting wear, fretting map, vibro-impact dynamics
pages
221 pages
publisher
Division of Solid Mechanics Lund University, Box 118, SE-221 00 Lund, Sweden
defense location
Room M:2469, M-building, Ole Römers väg 1, Lund Institute of Technology
defense date
2005-06-14 13:15
external identifiers
  • other:ISRN:LUTFD2/TFHF-05/1032-SE(1-216)
ISBN
91-628-6513-7
language
English
LU publication?
yes
id
6854f7ef-86ad-4f73-b213-e6fa76b50711 (old id 545074)
date added to LUP
2007-09-10 12:37:21
date last changed
2016-09-19 08:45:02
@phdthesis{6854f7ef-86ad-4f73-b213-e6fa76b50711,
  abstract     = {The topic of this thesis is dynamics and<br/><br>
<br/><br>
wear of structures. In the six appended papers different aspects of<br/><br>
<br/><br>
wear and dynamics of a model system are studied. The considered<br/><br>
<br/><br>
system consists of a long slender rod with unilateral supports,<br/><br>
<br/><br>
subject to harmonic and stochastic excitation. The rod is held at<br/><br>
<br/><br>
one end with stiff springs preventing translation and rotation and<br/><br>
<br/><br>
constrained by loose supports near the other.<br/><br>
<br/><br>
In the first two papers the vibration and impact dynamics of the<br/><br>
<br/><br>
model system subject to periodic and stochastic forcing are<br/><br>
<br/><br>
analysed. The wear work rates at impact points are evaluated with or<br/><br>
<br/><br>
without friction. Model computations are compared with measurements<br/><br>
<br/><br>
of contact forces and displacements made on a loosely supported rod<br/><br>
<br/><br>
with nuclear fuel dimensions. The comparison validates the modeling.<br/><br>
<br/><br>
The first two papers also contain global bifurcation analysis of<br/><br>
<br/><br>
idealized versions of the model system for both harmonic and<br/><br>
<br/><br>
stochastic loading. Regions of periodic and stochastic response are<br/><br>
<br/><br>
identified for the case of periodic forcing. The regions of stable<br/><br>
<br/><br>
periodic response are subjected to stability and bifurcation<br/><br>
<br/><br>
analyses in the third paper. The fourth paper focuses on the<br/><br>
<br/><br>
transition from stable periodic to chaotic response and the<br/><br>
<br/><br>
existence of stable multi periodic solutions within the chaotic<br/><br>
<br/><br>
regime. The third paper also contains an evaluation of the wear work<br/><br>
<br/><br>
rate along the identified stable paths of period one solutions. In<br/><br>
<br/><br>
the fourth paper a wear law is introduced which enables life time<br/><br>
<br/><br>
predictions of such stable solutions. The basin of attraction for a<br/><br>
<br/><br>
stable solution is also discussed.<br/><br>
<br/><br>
The sliding amplitude is usually in the fretting range for impacting<br/><br>
<br/><br>
systems such as the model considered in this thesis. The fifth<br/><br>
<br/><br>
paper deals with fretting wear maps to differentiate different<br/><br>
<br/><br>
regimes of fretting contact. A systematic method to compare fretting<br/><br>
<br/><br>
wear data from different sources with different contact geometries<br/><br>
<br/><br>
is developed. The method is applied to experimental data and new<br/><br>
<br/><br>
maps are presented in the form of dimensionless variables.<br/><br>
<br/><br>
The last paper deals directly with breakdown of materials due to<br/><br>
<br/><br>
wear induced loads. An idealized spring model is used to show that<br/><br>
<br/><br>
breakdown of disordered media due to applied shear forces behaves<br/><br>
<br/><br>
like a first order phase transition in condensed matter systems.<br/><br>
<br/><br>
Finally, the burst size distribution during rupture is evaluated and<br/><br>
<br/><br>
it is shown that the system behaves like the fiber bundle model with<br/><br>
<br/><br>
global load sharing.},
  author       = {Knudsen, Jakob},
  isbn         = {91-628-6513-7},
  keyword      = {vibration and acoustic engineering,Mechanical engineering,hydraulics,chaos,interfacial breakdown,stability,Maskinteknik,hydraulik,vakuumteknik,vibrationer,akustik,vacuum technology,fretting wear,fretting map,vibro-impact dynamics},
  language     = {eng},
  pages        = {221},
  publisher    = {Division of Solid Mechanics Lund University, Box 118, SE-221 00 Lund, Sweden},
  school       = {Lund University},
  title        = {Some Aspects of Wear and Structural Dynamics},
  year         = {2005},
}