PSI - Issue 53

Andrea Zanichelli et al. / Procedia Structural Integrity 53 (2024) 3–11 Author name / Structural Integrity Procedia 00 (2019) 000–000

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axial-torsional) fatigue tests. The results are also grouped by loading ratio R and phase angle β (in the case of biaxial loading). It can be pointed out that quite satisfactory results are obtained, since the theoretical results lie within the scatter bands 2 or 3 in most cases, and this applies regardless of the loading conditions. The T RMS values are reported in Figure 4 for the specimens with sharp, circular and blunt notches, by grouping the tests characterised by the same values of R and β . In the case of 0 β = ° , the lower T RMS value is obtained for the blunt notched specimens. On the other hand, for 90 β = ° , blunt notched specimens or circular notched ones are characterised by the lower T RMS value, when a loading ratio equal to either -1 or 0 is considered. Moreover, the overall values of T RMS are equal to 1.95, 2.19 and 2.83 for blunt, circular and sharp notched specimens, respectively.

4.0

β =0°, R=0 β =0°, R=-1 β =90°, R=0 β =90°, R=-1

3.0

2.0

T RMS

1.0

0.0

SHARP CIRCULAR BLUNT

Fig. 4. T RMS values related to the present analytical methodology for the specimens with: a sharp notch (root radius r =0.07 mm), a circular notch (root radius r =2 mm) and a blunt notch (root radius r =5 mm).

Therefore, it can be concluded that, by employing the present analytical methodology, a quite good accuracy is obtained in terms of fatigue life assessment of notched specimens made of the examined additively manufactured AISI 316L stainless steel. As a matter of fact, in the case of blunt notch, the same accuracy of the plain fatigue specimens is obtained. 5. Conclusions In the present paper, an analytical methodology has been proposed for the fatigue life estimation of additively manufactured metals subjected to cyclic loading. In particular, such a methodology is based on the Carpinteri et al. criterion and the Critical Direction Method and has been applied to an experimental campaign available in the literature, related to both plain and notched AM stainless steel specimens. Satisfactory results have been obtained, with the overall T RMS values lower than 2 for plain specimens and blunt notched specimens, slightly higher than 2 for circular notched specimens, and lower than 3 in presence of a sharp notch. Furthermore, the level of accuracy appears to be almost independent of the load configuration. This fact confirms the robustness of the applied methodology, which is able to provide satisfactory results, irrespective of the specimen type, the loading type, the degree of multiaxiality and non-proportionality.