PSI - Issue 18

P. Corigliano et al. / Procedia Structural Integrity 18 (2019) 280–286 Corigliano et al./ Structural Integrity Procedia 00 (2019) 000–000

285

6

= T i – T 0 ), during the tensile test. From the same graph it is also clearly visible that there is an initial phase in which the temperature variation has an almost constant slope (thermoelastic phase) and then tends to stabilize during a second phase. The change in the slope of the temperature increment can be easily find as the intersection between the straight line of regression of the thermoelastic region and the straight line of the zero derivative flex region. The corresponding stress value is around 169 MPa. The tests have shown that the slope change between 160 MPa and 180 MPa.

Fig. 7. Maximum temperature evolution during a tensile test.

The values obtained using the two different approaches of traditional fatigue tests and Static Thermographic Method, seem to be in good agreement, as the obtained scatter is normal for welded joints also during traditional

fatigue tests. Conclusion

Full-field techniques were applied for the study of S355 specimens. The DIC technique allowed the detection of strain field and the mechanical properties evaluation. The IR technique allowed the application of the Thermographic Method. The thermographic measurements during static tests can be used to predict the fatigue limit. The predictions of the fatigue life, obtained by means of the thermographic method during static tensile tests, were compared with the value obtained by the traditional procedure. The predicted values are in good agreement with the experimental values of fatigue life. The results gave interesting information for the development of prediction models for the fatigue life assessments of welded joints. References [2] Dulieu-Barton JM, Stanley P. Development and applications of thermoelastic stress analysis. J. Strain Analysis 1998;33(2):93–104. [3] Gigliotti M, Pannier Y, Minervino M, Lafarie-Frenot MC, Corigliano P. The effect of a thermo-oxidative environment on the behaviour of multistable [0/ 90] unsymmetric composite plates. Compos Struct 2013;106:863–72. [4] Crupi V, Guglielmino E, Risitano G, Tavilla F. Experimental analyses of SFRP material under static and fatigue loading by means of thermographic and DIC techniques. Compos B Engng 2015;77:268–77. [5] Bucci V, Corigliano P, Crupi V, Epasto G, Guglielmino E, Marinò A. Experimental investigation on Iroko wood used in shipbuilding. P. I. Mech. Eng. C-J. Mec. 2017;231:128–39. [6] Corigliano P, Crupi V, Guglielmino E. Non linear finite element simulation of explosive welded joints of dissimilar metals for shipbuilding applications, Ocean Eng. 160 2018; 346–353. [1] Hayabusa K, Inaba K, Ikeda H, Kishimoto K. Estimation of Fatigue Limits from Temperature Data Measured by IR Thermography. Exp Mech 2017;57:185–94. doi: http://dx.doi.org/10.1007/s11340-016-0221-7.