PSI - Issue 83

Davide D’Andrea et al. / Procedia Structural Integrity 83 (2026) 256–264

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material in its final stress level (Figure 3-a) stabilization phase was not reached and the self-heating effect caused the specimen to reach temperatures above 300°C. On the other hand, the AM material (Figure 3-b) exhibited a lower temperature increase, and in the final loading step the three characteristic phases are clearly distinguishable. In this case, temperatures only slightly above 50 °C were recorded.

(a)

(b)

Figure 4. Temperature’s trend obtained for a) traditionally manufactured and b) AM specimens

After temperature’s trend over cycles have been measured and stabilization temperatures have been calculated, it is possible to estimate the fatigue limit by calculating the intersection point of two regression lines describing the relationship between the stabilization temperature reached for stresses below (I subset) and above (II subset) the fatigue limit. This methodology led to the determination of the fatigue limit, calculated as the average of the two stepwise fatigue tests, yielding values of 303.5 MPa for the traditionally manufactured specimens and 275 MPa for the AM specimens, evidencing a 9.4% reduction in fatigue resistance.