PSI - Issue 19

Rainer Wagener et al. / Procedia Structural Integrity 19 (2019) 380–387 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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fatigue, the Fatigue Life Curve should be the first choise to be integrated into a digital twin in order to consider the aspects of fatigue in the virtual reality.

Figure 10: Comparison of stress- and strain-controlled fatigue test results in the strain domain

Keeping in mind the small sample size of this investigation, at least for additive by laser powder bed fusion manufactured AlSi10Mg the results of stress- and strain-controlled fatigue tests are equivalent, neglecting the plastic strain proportion. Influences like the orientation of the built to the load directions are also considered.

3.3 Cyclic stress-strain behavior

The second required input parameter in order to perform a numerical fatigue approach is the stress-strain behavior. The fastest way to derive the stress-strain behavior experimentally is to carry out Incremental Step Tests. Therefore, maximum loads of  a,t,max = 0.8% and 0.4% are used. In order to derive the properties of the stress-strain relation, which have been established by Ramberg and Osgood (1943), the reversal point of the first and third quadrant, which means from tension and compression loading conditions, are used.

Figure 11: Cyclic stress-strain curve derived by Incremental Step Tests with different maximum loading and load orientation

Under low load amplitudes, the Young’s modulus of the X -oriented specimens is higher than of Z-orientation, Fig. 11. On the other hand, the transition from macroscopic elastic to elastic-plastic stress-strain behavior takes place at