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@PHDTHESIS{Ebrahem:814823,
      author       = {Ebrahem, Firaz},
      othercontributors = {Markert, Bernd and Rolfes, Raimund},
      title        = {{M}olecular structure-property relationships of network
                      glasses under mechanical loading},
      volume       = {IAM-09},
      school       = {Rheinisch-Westfälische Technische Hochschule Aachen},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {RWTH Aachen University},
      reportid     = {RWTH-2021-02363},
      series       = {Report. IAM, Institute of General Mechanics},
      pages        = {1 Online-Ressource : Illustrationen, Diagramme},
      year         = {2021},
      note         = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University; Dissertation, Rheinisch-Westfälische Technische
                      Hochschule Aachen, 2021},
      abstract     = {Generally, glasses are hard and transparent solids that are
                      very resistant to corrosion, and show superb electrical and
                      thermal insulating properties. Therefore, glasses are used
                      across a broad range of industrial applications. Despite
                      extensive research into their structure and properties, the
                      highly complex mechanical behaviour remains, to date, poorly
                      understood. It is widely accepted that the interrelation
                      between the structure and the way a material behaves is of
                      central significance for materials engineering. For
                      crystals, finding structure-property relationships has been
                      carried out successfully over the past decades. The
                      periodicity of crystalline materials allows for a clear
                      picture of the molecular structure, for instance via
                      observation of dislocations by transmission electron
                      microscopy. This led to the development of material models,
                      such as crystal plasticity that is based on the dislocation
                      slip mechanisms in a crystal lattice. On the contrary,
                      finding such relationships for glassy solids has been
                      limited by the difficulty in imaging their structure due to
                      the lack of long-range order. Yet, it is quite natural that
                      the properties of glasses are sensitive to the molecular
                      structure. Therefore, the aim of this thesis is to
                      understand how this structure dictates the deformation
                      behaviour of a glass. Using molecular simulations, the
                      structure-property relationships are investigated for silica
                      glass, forming a network of covalently-bonded silicon and
                      oxygen atoms. Thereby, the main focus lies on numerical
                      methods and approaches that enable quantitative engineering
                      of network glasses to achieve desired mechanical properties.
                      First, bulk silica glass is realised by quenching the melt.
                      Although lacking long-range order, the glass network can be
                      evaluated statistically by means of the ring topology, i.e.
                      the ring size distribution, where a ring is composed of a
                      number of covalent bonds within it. By the use of different
                      quenching rates, it is shown that the thermal history
                      strongly influences the network topology. Subsequent
                      deformation of the glass samples reveals that a change in
                      the network topology results in stress-strain relations
                      which vary to a significant degree. Based on this, in
                      particular, the plastic deformation can directly be linked
                      to the network topology. Furthermore, a 2D glass model is
                      introduced based on statistical data extracted from recently
                      discovered 2D silica. The two-dimensionality of this model
                      allows for the direct observation of the molecular structure
                      during deformation. In this way, the imaging limitations of
                      the complex 3D network of bulk silica glass can be overcome.
                      The 2D silica glass is investigated under both tensile and
                      shear deformation. The athermal quasi-static deformation
                      method is applied in order to study how the pure structural
                      disorder correlates with the stress response. Here, the main
                      objective is to identify and evaluate the elementary
                      inelastic events which are localised rearrangements of a
                      small number of atoms. In addition, the
                      crystalline-to-vitreous transition is explored by
                      controlling the network structure.},
      cin          = {411110},
      ddc          = {620},
      cid          = {$I:(DE-82)411110_20140620$},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      doi          = {10.18154/RWTH-2021-02363},
      url          = {https://publications.rwth-aachen.de/record/814823},
}