Abstract
This paper regards the rapid determination of fatigue limit by using thermal data analysis. Different approaches available in the literature to estimate the fatigue limit of cold-drawn AISI 304L bars are analyzed and compared, namely, temperature- and energy-based methods. Among the temperature-based approaches, the Risitano Method (RM) and the method based on material temperature evolution recorded during a static tensile test were analyzed. Regarding the energy-based approaches, the input mechanical energy density stored in the material per cycle (i.e., the area of the hysteresis loop), the heat energy dissipated by the material to the surroundings per cycle, and the “2nd-harmonic-based” methods were considered. It was found that for the material analyzed, all the considered energy-based approaches provided a very good engineering estimation of the material fatigue limit compared to a staircase test.
Highlights
Fatigue is an irreversible process, accompanied by microstructural changes, localized plastic strains, and energy dissipation
The temperature rise of a metallic material undergoing a fatigue test is a manifestation of the thermal energy dissipation, and it was experimentally observed that the higher the applied stress amplitude, the more pronounced the temperature increase of the material
The trend of the observed temperature increase versus the applied stress amplitude presents a relatively abrupt change at a certain stress level. This characteristic stress amplitude is associated with the material fatigue limit [1,2,3,4,5,6,7]
Summary
Fatigue is an irreversible process, accompanied by microstructural changes, localized plastic strains, and energy dissipation. The temperature rise of a metallic material undergoing a fatigue test is a manifestation of the thermal energy dissipation, and it was experimentally observed that the higher the applied stress amplitude, the more pronounced the temperature increase of the material. The trend of the observed temperature increase versus the applied stress amplitude presents a relatively abrupt change at a certain stress level. This characteristic stress amplitude is associated with the material fatigue limit [1,2,3,4,5,6,7]. Risitano and Risitano [8] proposed an even faster experimental approach to estimate the material fatigue limit, consisting in monitoring the material temperature during a simple static tensile test
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