Untersuchungen der Thermoschockbelastungen an keramischen Kugeln und Balken mit künstlichen Defekten

Translated title of the contribution: Analysis of thermal quenching on ceramic balls and prismatic bars with artificial defects

Franz Alois Adlmann

Research output: ThesisDiploma Thesis


Ceramic balls are used as rolling elements in highly loaded bearings. Recent research (e.g. strength measurement using the “Notched Ball Test“) has shown that small surface defects can lead to a significant decrease in the mechanical strength of components. A sudden change in temperature (i.e. thermal shock) causes transient stress fields depending on thermo-elastic material properties, sample geometry, heat transfer coefficient and temperature difference, which can initiate cracks at the surface of the part leading to failure under certain circumstances. According to the Griffith-Irwin criterion cracks originate from pre-existing “crack like” defects by exceeding a certain load threshold, the so-called stress intensity factor. In the theoretical part of this work the time and position related stress intensity factor in the vicinity of a semi-elliptical crack tip during rapid quenching of balls and prismatic bars is calculated using Finite Element (FE) simulations. Experimental validation is accomplished by introducing reproducible near semi-elliptical cracks in apt samples. Henceforth through subsequent quenching of the parts in water and systematic increase of the temperature difference the critical load initiating damage through crack initiation can be determined. It has been shown that validated FE models can predict the geometry and position of defects which may cause the failure of the part during the quenching process.
Translated title of the contributionAnalysis of thermal quenching on ceramic balls and prismatic bars with artificial defects
Original languageGerman
  • Supancic, Peter Hans, Supervisor (internal)
Award date29 Jun 2012
Publication statusPublished - 2012

Bibliographical note

embargoed until 05-06-2017


  • thermal quenching
  • MFE
  • fracture mechanics
  • ceramic
  • siliconnitride

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