@inproceedings{ChristovPetkov2000,
  author    = {Christov, Christo T. and Petkov, Zdravko B.},
  title     = {DETERMINATION OF THE DYNAMIC STRESS INTENSITY FACTOR USING ADVANCED ENERGY RELEASE EVALUATION},
  doi       = {10.25643/bauhaus-universitaet.577},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-5770},
  year      = {2000},
  abstract  = {In this study a simple effective procedure practically based upon the FEM for determination of the dynamic stress intensity factor (DSIF) depending on the input frequency and using an advanced strain energy release evaluation by the simultaneous release of a set of fictitious nodal spring links near the crack tip is developed and applied. The DSIF is expressed in terms of the released energy per unit crack length. The formulations of the linear fracture mechanics are accepted. This technique is theoretically based upon the eigenvalue problem for assessment of the spring stiffnesses and on the modal decomposition of the crack shape. The inertial effects are included into the released energy. A linear elastic material, time-dependent loading of sine type and steady state response of the structure are assumed. The procedure allows the opening, sliding and mixed modes of the structure fracture to be studied. This rational and powerful technique requires a mesh refinement near the crack tip. A numerical test example of a square notched steel plate under tension is given. Opening mode of fracture is studied only. The DSIF is calculated using a coarse mesh and a single node release for the released energy computation as well a fine mesh and simultaneous release of four links for more accurate values. The results are analyzed. Comparisons with the known exact results from a static loading are presented. Conclusions are derived. The values of the DSIF are significantly larger than the values of the corresponding static SIF. Significant peaks of the DSIF are observed near the natural frequences. This approach is general, practicable, reliable and versatile.},
  subject      = {Bruchmechanik},
  language  = {en}
}
@phdthesis{Alt2000,
  author    = {Alt, Dieter von},
  title     = {Ausbruchverhalten von Porenbetonplatten bei randnaher Punktst{\"u}tzung},
  doi       = {10.25643/bauhaus-universitaet.56},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20040310-591},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2000},
  abstract  = {Schwerpunkt dieser Arbeit ist die Untersuchung des Ausbruchverhaltens von unbewehrten Porenbetonplatten bei konzentrierter Lasteintragung in Randn{\"a}he. In der Praxis tritt diese Problematik bei Befestigungen oder Verankerungen auf, die eine punktuelle Beanspruchung bewirken. Hauptziel der durchgef{\"u}hrten experimentellen und numerischen Untersuchungen war das Erkennen von Gesetzm{\"a}ßigkeiten f{\"u}r Versagenserscheinungen und f{\"u}r Bruchlasten in Abh{\"a}ngigkeit von variierenden Geometrie- und Materialparametern. Dabei waren Gr{\"o}ße und Lage der Lasteinleitungsstelle sowie die Materialfestigkeit die wichtigsten Einflussfaktoren. Von besonderem Interesse war auch das spr{\"o}de Verhalten des Porenbetonmaterials auf das Ausbruchverhalten. Die Arbeit gliedert sich in drei Hauptteile: die Experimente mit anschließend weiterf{\"u}hrenden numerischen Untersuchungen, sowie Bemessungskonzepten mit Ausbruchgleichungen. Ein weiteres Kapitel behandelt die Zugfestigkeit von Porenbeton. Die Experimente wurde an f{\"u}r Wand- oder Deckenplatten originaldicken Versuchsk{\"o}rpern durchgef{\"u}hrt. Dabei waren die Lagerbedingungen so festgelegt, dass sich m{\"o}glichst ein ungest{\"o}rter Ausbruchk{\"o}rper ausbilden konnte. Numerische Spannungsuntersuchungen {\"u}ber eine r{\"a}umliche Idealisierung der Versuchsk{\"o}rper mit dem Finite- Element- Programmsystem ANSYS gaben Aufschl{\"u}sse {\"u}ber Ort und Gr{\"o}ße von bruchverursachenden Spannungen. Des weiteren wurden {\"u}ber die Versuchsergebnisse hinaus Berechnungen {\"u}ber den Einfluss von Variationen bei der Plattengeometrie durchgef{\"u}hrt. Es wurden Betrachtungen {\"u}ber die Zugfestigkeit als einen maßgebenden Faktor f{\"u}r das Ausbruchverhalten gef{\"u}hrt. Numerische Risssimulationen gaben Aufschluss {\"u}ber den Spannungszustand und den Ablauf der Rissentwicklung.},
  subject      = {Platte},
  language  = {de}
}
@inproceedings{EbertBucher2000,
  author    = {Ebert, Matthias and Bucher, Christian},
  title     = {Modelling of changing of dynamic and static parameters of damaged R/C},
  doi       = {10.25643/bauhaus-universitaet.582},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-5825},
  year      = {2000},
  abstract  = {Dynamic testing for damage assessment as non-destructive method has attracted growing in-terest for systematic inspections and maintenance of civil engineering structures. In this con-text the paper presents the Stochastic Finite Element (SFE) Modeling of the static and dy-namic results of own four point bending experiments with R/C beams. The beams are dam-aged by an increasing load. Between the load levels the dynamic properties are determined. Calculated stiffness loss factors for the displacements and the natural frequencies show differ-ent histories. A FE Model for the beams is developed with a discrete crack formulation. Cor-related random fields are used for structural parameters stiffness and tension strength. The idea is to simulate different crack evolutions. The beams have the same design parameters, but because of the stochastic material properties their undamaged state isn't yet the same. As the structure is loaded a stochastic first crack occurs on the weakest place of the structure. The further crack evolution is also stochastic. These is a great advantage compared with de-terministic formulations. To reduce the computational effort of the Monte Carlo simulation of this nonlinear problem the Latin-Hypercube sampling technique is applied. From the results functions of mean value and standard deviation of displacements and frequencies are calcu-lated. Compared with the experimental results some qualitative phenomena are good de-scribed by the model. Differences occurs especially in the dynamic behavior of the higher load levels. Aim of the investigations is to assess the possibilities of dynamic testing under consideration of effects from stochastic material properties},
  subject      = {Stahlbetonbauteil},
  language  = {en}
}