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@PHDTHESIS{Nordhorn:188045,
      author       = {Nordhorn, Christian},
      title        = {{S}pannungsinduziertes {V}ersagen in
                      {H}ochtemperaturschichtsystemen},
      volume       = {241},
      school       = {Ruhr-Universität Bochum},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2015-01523},
      isbn         = {978-3-95806-016-6},
      series       = {Schriften des Forschungszentrums Jülich, Reihe Energie
                      $\&$ Umwelt / Energy $\&$ Environment},
      pages        = {118 S.},
      year         = {2014},
      note         = {Ruhr-Universität Bochum, Diss., 2014},
      abstract     = {Ceramic components in high-temperature coating systems are
                      prone to stress-induced failure because of thermal mismatch
                      and system specific degradation processes. Lifetime models
                      are developed, in order to identify the underlying
                      mechanisms of system failure and to assess the coating
                      system reliability. A probabilistic lifetime model was
                      developed for calculations of the durability of
                      atmospherically plasma sprayed thermal barrier coating
                      systems under thermo-cyclic loading. The model algorithm
                      includes finite element analyses of thermally induced stress
                      fields in consideration of thermally induced oxide scale
                      growth, sintering of the ceramic topcoat, stress relaxation,
                      and microstructural features of the ceramic-metal interface.
                      To reduce the computing time, the interface of
                      two-dimensional models was approximated by periodic
                      functions, which are parameterized based on experimentally
                      determined surface roughness parameters. The results of
                      stress measurements in grown oxide scales by
                      photo-stimulated luminescence-spectroscopy validated the
                      implementations of mechanical boundary conditions, material
                      parameters, and the methodology of microstructure
                      approximation for the subsystem without topcoat. Lifetime
                      relevant stress field distributions calculated on the basis
                      of interface approximation functions were found to be in
                      accordance with stress distributions from three-dimensional
                      finite element analyses with realistic interface structures,
                      which were imported from topography measurements. The
                      lifetime model requires a calibration by presetting an
                      experimental lifetime distribution. The associated cycle
                      dependent calibration parameter re ects the effect of
                      fracture toughness increase for increasing crack length. The
                      calculated stress field distributions are employed in
                      fracture mechanical analyses of subcritical crack growth. A
                      comparison of the transient energy release rate with its
                      crack length dependent critical value results in cumulative
                      distribution functions for the probability of system
                      lifetime in dependence of the cycling conditions. Calculated
                      lifetime expectation values and standard deviations were
                      found to be in accordance to experimental lifetimes
                      determined as a function of interface temperature. The
                      stress field inversion rate directly correlated to oxide
                      scale growth rate was identified as main failure mechanism.
                      Sensitivity analyses were conducted with regard to further
                      parameter effects on the lifetime. The lifetime model
                      algorithm was abstracted and applied to the stress induced
                      failure of chromium evaporation barriers in stacks of solid
                      oxide fuel cells providing a conceptual modelling approach.},
      keywords     = {Dissertation (GND)},
      cin          = {IEK-1},
      cid          = {I:(DE-Juel1)IEK-1-20101013},
      pnm          = {122 - Power Plants (POF2-122)},
      pid          = {G:(DE-HGF)POF2-122},
      typ          = {PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/188045},
}