Entwicklung einer Umlaufbiegeprüfmaschine zur Bewertung des Größeneffekts zyklisch beanspruchter Komponenten

Translated title of the contribution: Development of a rotating bending test machine for the assessment of the size effect of cyclic stressed components

Markus Doppler

Research output: ThesisMaster's Thesis


Due to the increasing requirements for mechanical engineering components to an enhancement of lifetime and reduction of weight, a dimensioning according to economic and fatigue strength aspects is essential. For components of huge dimension, like railway bogies, an additional fatigue influence factor has to be considered, the size effect. In the scope of this master thesis, the development and assembling of a rotating bending test machine for large specimens up to a diameter of 60 mm is performed. Machine depending activities include the development, final approval at the manufacturer, final assembling at the testing labour, as well as the installation of a measurement system and sensors. As part of the start-up, the measurement system is calibrated, validated by preliminary tests and finally adjusted. Furthermore, an existing control system is rebuilt for the requirements of the constructed test machine. The experimental investigations include constant amplitude fatigue tests of notched and unnotched round specimens made of austenitic steel with a testing diameter of 30 mm. The results of the large specimens are compared to existing test results of smaller specimens with a testing diameter of 6 mm, whereat a decrease of the high-cycle fatigue strength of about 10% was determined. The specimens are analysed according to the stress mechanical and statistical size effect, based on recent published concepts. Therefore, it is necessary to conduct an entire numerical analysis of the small and large specimen geometries to evaluate the most important parameters of the concepts, the stress gradient and the highly stressed volume. The constant amplitude fatigue test results and the fatigue assessment shows, that it is possible to use the volume corrected stress gradient model for the endurance limit of the investigated austenitic steel. Based on the developed rotating bending machine and the testing method, it is scheduled to analyse the size effect in case of crack containing large specimens.
Translated title of the contributionDevelopment of a rotating bending test machine for the assessment of the size effect of cyclic stressed components
Original languageGerman
  • Leitner, Martin, Co-Supervisor (internal)
  • Grün, Florian, Supervisor (internal)
Award date26 Jun 2015
Publication statusPublished - 2015

Bibliographical note

embargoed until 18-03-2020


  • Rotating bending test machine
  • large specimens
  • fatigue strength
  • size effect
  • stress gradient model
  • highly-stressed volume

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