Issue 43

P. Corigliano et alii, Frattura ed Integrità Strutturale, 43 (2018) 171-181; DOI: 10.3221/IGF-ESIS.43.13 179 square of the corresponding maximum applied load, P 2 max , and the data obtained were interpolated using a linear regression (Fig. 14). The fatigue strength can be estimated by the intersection of the regression line with the abscissa axis; the point located corresponds to the maximum stress below which there is no change in temperature. In the specific case, the fatigue limit P max estimated using the Thermographic Method [21] is about 8.7 kN and corresponds with good approximation to the value identified by the P max - N curve (P max vs number of cycles to failure) obtained from the experimental fatigue tests, see Fig. 15, where the fatigue strength seems to be between 8 kN and 9 kN. Figure 16: Linear regression values ΔT AS in function of P 2 max. Figure 15: P max – N diagram. C ONCLUSION he fatigue behavior of titanium welded joints was analyzed, the welding was performed using a laser source and in the absence of filler material. Structural analyses were complemented by full-field investigations, thanks to the use of two non-destructive techniques such as the Digital Image Correlation technique and Infrared Thermography. Specifically, the analysis by means of DIC allowed detecting strain gradients in the surrounding area of the welding and the cumulative damage induced by the loading history. By means of the IRT technique was possible to analyze the evolution of the surface temperature of the welded joints during fatigue tests and apply the Thermographic Method in T