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Lecture

Experimental Characterization of Crack Initiation in High Performance Steels for the Development and the Benchmarking of Material Models for the Fatigue Life Prediction

Wednesday (26.09.2018)
15:30 - 15:45 S1/01 - A02
Part of:


A material’s fatigue lifetime is determined by the crack formation process: damage accumulation in individual grains, micro crack initiation, short crack formation. In the past years the implementation of a novel high-throughput methodology for fatigue damage evolution investigation has been presented. This has been achieved by sample size reduction and implementation of a sensitive measurement setup, where the sample resonant frequency decrease correlates to damage initiation. This methodology gives in-situ insights of the damage evolution distribution in individual grains and neighbors, depending on the number of cycles, the local stress amplitude, and the grain orientation. Images obtained in-situ with an optical camera and stroboscope illumination, are used as an input for SEM automatization in order to receive extrusion images on the whole sample. This contribution will present fatigue results and damage initiation of bcc samples; as well as how the methodology can estimate parameters (such as slip band width or spacing and cyclic irreversibilities) for life time prediction, for example Microstructure-Based Fatigue-Crack-Initiation Model (Chan2003).

Speaker:
Ali Riza Durmaz
Fraunhofer Institute for Mechanics of Materials IWM
Additional Authors:
  • Michael Buck
    Fraunhofer Institute for Mechanics of Materials IWM / University of Freiburg
  • Prof. Dr. Christoph Eberl
    Fraunhofer Institute for Mechanics of Materials IWM / University of Freiburg
  • Dr. Thomas Straub
    Fraunhofer Institute for Mechanics of Materials IWM