PSI - Issue 83

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

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fatigue tests (Wei et al., (2024). In particular, thermoelastic effect demonstrated to be very useful to get insights into fatigue life by monitoring surface temperature’s trend of specimens subjected to cyclic loads. La Rosa & Risitano, (2000) first proposed the Risitano’s Thermographic Method (RTM) as a tool to rapidly determine the fatigue limit through surface temperature monitoring by infrared (IR) thermography. IR thermography can be employed to get insights into crack initiation and propagation: Vieira et al., (2017) used thermoelastic stress analysis (TSA) to monitor crack-tip position and correlate it to the number of cycles and analyses raw temperature measurement to determine the crack growth rate to fit polycarbonate characteristic Paris Law. Similarly, Fedorova et al., (2012), employed IR thermography to calculate J-integral and Stress Intensity Factor (SIF). Starting from the authors' experience on the fatigue characterization of AISI 316L stainless steel (Crisafulli et al., (2024); Santonocito et al., (2023)), the methodology proposed by Risitano et al., (2015) was applied to temperature’s data obtained by monitoring dogbone specimens. Finally, results demonstrated how a physical model can be obtained to get insights into crack propagation behavior of materials. Additionally, it was observed how the AM AISI316L counterpart is characterized by lower plastic work ratio.

Nomenclature AM

Additive Manufacturing Constant Amplitude High Cycle Fatigue

CA

HCF

IR Infrared Thermography LPBF Laser Powder Bed Fusion RTM Risitano’s Thermographic Method SLM Selective Laser Melting

2. Material and methods Two specimens’ batch were designed accordingly to hourglass geometry described in ASTM E466 standard. The first was manufactured with turning and the second adopting a Selective Laser Melting (SLM) printer 3D4Steel® (3D4Mec, Italy). They were printed along the Z direction aligned with loading axis, with a laser power of 210W and a laser scanning speed of 800 mm/s. The height of each layer was 50 μ m with a hatch spacing of 0.14 mm. The printing process was performed in nitrogen atmosphere with a printing volume of 210×210×230mm 3 . No post processing was performed on AM specimens. Turned and AM specimens are finally shown respectively in Figure 1-a e 1-b, together with dimensions expressed in millimeters in Figure 1-c. More information can be retrieved in Crisafulli et al., (2024).

(a)

(b)

(c)

Figure 1.a) Conventionally manufactured and b) additively manufactured specimens; c) specimens dimensions expressed in millimeters.

Mechanical properties derived from literature analysis are reported in Table 1. Ponticelli et al., (2022) observed a decrease in Young’s Modulus for AM AISI316L with respect to the traditionally manufactured counterpart of 11%