Issue 41

Y. Nadot et alii, Frattura ed Integrità Strutturale, 41 (2017) 220-226; DOI: 10.3221/IGF-ESIS.41.30 226 - A local criterion is not able to correlate the 7 different load cases with different initiation sites (up to 180 % error). - The Welded Stress Gradient criterion proposed improves the estimation of the fatigue limits but still some case leads to 65 % error. - Under fatigue spectrum (variable amplitude loading) the evaluation of the fatigue life needs nonlinear cumulative damage rules. The value of the material parameter used in the damage rule is a function of both material and spectrum so that further studies are needed to improve these theories. Figure 11 : Comparison between linear and non-linear cumulative damage under tension and bending. R EFERENCES [1] Dal Cero Coelho, F., Nadot, Y., Halm, D., Fatigue life assessment under complex multiaxial loading, Procedia Engineering, 133 (2015) 102 – 106. [2] Vu, Q.H., Halm, D., Nadot, Y., Multiaxial fatigue criterion for complex loading based on stress invariants, Int J Fatigue, 32(7) (2010) 1004-1014. [3] Manson, S., Halford, G., Practical implementation of the double linear damage rule and damage curve approach for treating cumulative fatigue damage, International Journal of Fracture, 17(2) (1981) 169–192.