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Keynote Lecture

WEB Multiscale experimental assessment and model-based correlation of fatigue damage evolution in additively manufactured metals

Thursday (24.09.2020)
09:00 - 09:30 S: Structural Materials 1
Part of:

The influence of microstructure, defects, and surface roughness induced during additive manufacturing (AM) processes have a detrimental effect on the fatigue strength and performance capability in structural applications. Ever improving testing equipment and methods with enhanced measurement precision enable tracking of the damage mechanisms at several levels of materials engineering scale. Measurement-based fatigue damage tracking during testing of SLM aluminum alloys revealed the interaction between porosity and microstructure under loading in the very high-cycle fatigue (VHCF) regime. The grain boundary strengthening of the microstructure increased VHCF strength by 33%. In SLM manufactured 316L steels, the direction-dependence of fatigue strength was investigated for 0°, 45°, and 90° samples. The fatigue strength could be correlated with the effective defect or pore size relative to the load direction using the Murakami concept. Finally, application-optimized instrumentation consisting of digital image correlation (DIC), quantitative acoustic emission (AE) analysis, and infrared thermography (IRT) was used for EBM manufactured cellular structures of IN718 nickel and Ti-6Al-4V titanium alloys. The localization of damage was detected by DIC and IRT, while the cascade-like damage evolution from strut to strut could be monitored by each measurement technique. Especially the fundamental AE analysis offers the possibility to be used as a condition monitoring system for intricate lattice AM structures and components. The previous and further examples are presented to reveal the potential to enhance the reliability of AM structures and components design based on comprehensive defect-microstructure-property relationships to be integrated into robust modeling approaches based on cyclic plasticity and real-time models of non-destructive measurement techniques.

The abstract is submitted following an invitation of Prof. Niendorf.

Mustafa Awd
TU Dortmund University
Additional Authors:
  • Felix Stern
    TU Dortmund University
  • Daniel Kotzem
    TU Dortmund University
  • Jochen Tenkamp
    TU Dortmund University
  • Prof. Frank Walther
    TU Dortmund University