PSI - Issue 68

Danilo D’Andrea et al. / Procedia Structural Integrity 68 (2025) 746–755 D’Andrea et al./ Structural Integrity Procedia 00 (2025) 000–000

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Figure 6. Comparison between STM, RTM and classical CA fatigue test results.

In Figure 6 is represented how STM confidence interval encompasses the fatigue strength determined with RTM, and that conducting constant amplitude fatigue tests around the stress limit results in both run outs and failures as expected when applying load near fatigue limit of material.

5. Conclusion In this work the mechanical properties and the fatigue behaviour of Nylon PA12 reinforced with 15% of carbon fibres have been studied. The specimens were printed using FDM technique, according to ASTM D638-type V standard. To evaluate the mechanical behaviour of the investigated specimens the Static Thermographic Method (STM), and the Risitano Thermographic Method (RTM) have been used. The limit stress obtained by STM was about 30 MPa, which agrees with the fatigue limit value of 31MPa obtained by adopting the RTM. The results of this work underline how the adoption of energy methods, and particularly the Static Thermographic Method, allows to determine an initial design parameter of material quickly and accurately, since stress limit is calculated to be !"# = 30.1 ± 1.3 MPa . However, more constant amplitude tests (classical fatigue tests) were programmed to confirm the results obtained with energy methods adopted determining SN curve following standards. Acknowledgements Thanks are extended to the University of Messina’s academic spin-off Knowow for providing access to the RFM testing machine for conducting the tests. References Curà, F., G. Curti, and R. Sesana. 2005. “A New Iteration Method for the Thermographic Determination of Fatigue Limit in Steels.” International Journal of Fatigue 27 (4): 453–59. https://doi.org/10.1016/j.ijfatigue.2003.12.009. Curti, G, G La Rosa, M Orlando, and A Risitano. 1986. “Analisi Tramite Infrarosso Termico Della Temperatura Limite in Prove Di Fatica.” Proceedings XIV Convegno Nazionale AIAS , 211–20. D’Andrea, Danilo, Giacomo Risitano, Eugenio Guglielmino, Elpida Piperopoulos, and Dario Santonocito. 2022. “Correlation between Mechanical Behaviour and Microstructural Features of AISI 316L Produced by SLM.” Procedia Structural Integrity 41: 199–207. https://doi.org/10.1016/j.prostr.2022.05.022.