PSI - Issue 83

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

260

0 2 ሻ

m ሺ σ r

A c,r

(6)

C 1 =

2 - σ A c,i C 1 m ሺ σ i

0 2 ሻ

(7)

Δ N c,i =

2 - σ

Figure 3 shows the implemented workflow for the present work.

Figure 3. Data analysis workflow

3.2. Relative Plastic Work Factor During the Fatigue Test Risitano et al., (2015) proposed a theoretical modeling based on the energy balance to estimate relative plastic work factor, i.e. the component of work related to irreversible plastic deformations transformed into heat during the phase B of temperature’s trend during a stepwise fatigue test. The formulation starts from the assumption that the work supplied from the outside, per volume unit and per cycle, can be split into two components consisting of the energy transformed into heat and the part which causes the variation of the internal energy. Additionally, for temperature below 80°C the conduction phenomenon can be neglected, focusing just on convection and irradiation. Equations reported in Risitano et al., (2015)., developed for rectangular cross section specimens, were adapted to the case of hourglass specimens resulting in equation 8, where E is the Young’s Modulus, K is a constant describing convection and irradiation, Δ T st is the stabilization temperature reached in the second phase of temperature’s trend, f is the test frequency, r is the circular cross section radius and σ sup is the maximum stress of cyclic load.

4 E K Δ T st f r σ sup 2

(8)

β p =

4. Results and discussion The analysis starts with discussion about RTM’s results. Figure 4 shows temperature’s trend over cycle during two representative stepwise fatigue tests carried out on traditionally manufactured AISI 316L and its AM counterpart. Red circles highlight the temperature’s data used to determine the stabilization temperature, while the green circles represent the point which determines the third phase of temperature’s trend. It is worth noting that for the traditional