Fatigue assessment by thermal analysis during tensile tests on steel

There are many studies in literature on the thermal response of composites during static tests for a prediction of the fatigue limit, but only few studies about the thermal response of steels during static tests, and, as far as the authors are aware, this study is the first one about the application of the Thermographic Method during static tensile tests for the fatigue assessment of steel welded joints. Tensile tests were carried out on base material and welded specimens, made of S690QL steel. The Digital Image Correlation and thermographic techniques have been used during all tests. Moreover fatigue tests at increasing loads were carried out on steel base material and welded specimens by a stepwise succession (applied to the same specimen) for applying the Thermographic Method. The predictions of the fatigue limit, obtained by the analysis of the temperature evolution during the static tests, were compared with the predictions obtained applying the Thermographic Method during fatigue tests.