PSI - Issue 53

R.F. Fernandes et al. / Procedia Structural Integrity 53 (2024) 144–150 Author name / Structural Integrity Procedia 00 (2019) 000–000 where σ �� represents the reversible stress amplitude (R=-1), σ � is the stress amplitude, and σ ��� is the maximum stress for a specific stress ratio. To consider the damage of the variable amplitude loading blocks, the Miner’s rule was employed, as described in Eq. (2) (Miner, 1945): ��∑ � � � � � ��� , (2) here, D represents the accumulated damage, k indicates the number of blocks, n � is the number of constant amplitude cycles applied during block characterized by a stress amplitude σ � , and N � represents the number of cycles to failure of the same block. Figure 4 shows the correlation between the predicted values, N p , obtained using Miner’s Law and the experimental results, N e for both the unnotched and notched specimens, as illustrated in Figure 4a) and 4b), respectively, for both the as-built and stress relief series. In Figures 4a) and 4b), the limits N p � 2 N f and N p � 0.5 N f were also plotted and applied as criteria for assessing the accuracy of predictions. 149 6

Fig. 4. Correlation between the predicted life and experimental life comparing As-built (AB) and Stress relief (SR) for: a) Unnotched specimens and b) Notched specimens.

In the unnotched specimens, a good agreement was observed between the experimental results and predicted values, as indicated by the majority of the results falling within the two defined limits. However, for notched specimens, the correlation is more conservative because Miner’s law does not account for the plasticity that occurs in the notch root. Based on the analysis of the figure, it can be concluded that Miner’s Law is suitable for predicting the fatigue life of unnotched specimens of AlSi10Mg produced by LPBF. However, in notched specimens, improvements are necessary for accurate predictions.