Implementierung des lokalen Rissschließverhaltens in die numerische Rissfortschrittssimulation

Translated title of the contribution: Implementation of local crack closure effects in numerical crack propagation simulation

Anna Juliana Gaugelhofer

Research output: ThesisMaster's Thesis


Process-related imperfections may appear, which can occur both in bulk volume and in the surface layer of the components. These imperfections cause stress concentrations when the components are cyclic loaded and therefore represent initiation points for cracks, which severely affect the service life. In industrial practice, the evaluation of cracked components is often based on linear elastic fracture mechanics. Since crack propagation tests are time-consuming and also cost-intensive, numerical crack propagation simulations are becoming the focus of industrial design processes. The simulation chain developed in this master thesis offers the possibility to numerically calculate local crack closure behavior of a two- and three-dimensional crack geometries. The basis for this is the modified NASGRO equation, which takes short crack growth into account in the calculation of the crack propagation rate. To validate this simulation chain, nine SENB specimens were subjected to crack propagation testing at different stress ratios of R = -1, 0, and 0.5. The resulting fracture mechanics material parameters serve as input parameters of the presented simulation chain and can be entered via an implemented user interface. Here, the fracture mechanics simulation chain offers not only the possibility of automated calculation of stress intensity factors and crack propagation rates, but also the execution of parameter studies on different crack geometries. The comparison with the physical tests shows that the simulation allows a proper estimation related to the crack propagation. Since tilted crack fronts often occur during specimen preparation, a parameter study was performed on the influence of the tiltedness of SENB-incipient cracks on crack propagation. It was found that the influence of the angular position is hardly present in the long crack regime due to an onsetting compensation of the crack front skew. In contrast, it is more pronounced in the short crack region, which leads to decrased long crack threshold being reached earlier. A generalized fracture mechanics parameter set was determined by the CD-Laboratory for Manufacturing Process-Based Component Design to cover the statistical size effect of the investigated material. It was found that the generalized dataset shifts the simulation results to conservative fatigue life cycles, especially for decreasing stress ratios.
Translated title of the contributionImplementation of local crack closure effects in numerical crack propagation simulation
Original languageGerman
Awarding Institution
  • Montanuniversität
  • Horvath, Michael, Co-Supervisor (internal)
  • Stoschka, Michael, Supervisor (internal)
Award date22 Oct 2021
Publication statusPublished - 2021

Bibliographical note

no embargo


  • fracture mechanics
  • crack growth simulation
  • local crack closure effect
  • cast steel

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