Issue 50

P. Livieri et alii, Frattura ed Integrità Strutturale, 50 (2019) 613-622; DOI: 10.3221/IGF-ESIS.50.52 621 0.42 mm. The dimensionless shape of the defects is reported in Fig. 9, where the half maximum diameter is considered in the dimensionless operation. The numerical results are shown in Fig. 10. The symbols represent the numerical values obtained by means of Eqn. (25), whereas the continuous line is the SIF calculated by considering the defect of Fig. 8 as a first order deviation of a circle (see reference [28] for details). In this case after the reading of the border in the Fourier series, the stress intensity factors are given as a sum of harmonic terms weighed by numerical coefficients derived from the Oore-Burns integral in a similar way to that obtained in references [29–30]. Figure 10 : SIF of the crack of Fig. 8 under uniform tensile loading σ n . ( a is half maximum diameter). C ONCLUSIONS he calculation of the stress intensity factor (SIF) of small circular defects located at the weld toe is possible without the use of specific numerical procedures despite the singularity of the stress field when the distance from the notch tip becomes zero. If the defects do not have a circular form, by taking advantage of the Oore-Burns weight function, a procedure is developed for cracks similar to a star domain. In this way, a more precise evaluation of the SIF is possible and the shape factor of non-convex defects should be estimated. The influence of mode II will be take into account in the future. R EFERENCES [1] Webster, S., Bannister, A. (2000). Structural integrity assessment procedure for Europe – of the SINTAP programme overview, Engineering Fracture Mechanics, 67(1), pp. 481–514. [2] Bueckner, H.F. (1970). A novel principle for the computation of stress intensity factors, ZAMM 50, pp. 529–546. [3] Rice, J.R. (1989). Weight function theory for three-dimensional elastic crack analysis. ASTM STP1020, Wei R.P. and Gangloff R.P., Eds. Philadelphia, American Society for Testing and Materials, pp. 29–57. [4] Fett, T., Munz, D. (1997). Stress intensity factors and weight functions, Computational Mechanics Publications. [5] Mastrojannis, E.N., Keer, L.M., Mura, T. (1979). Stress intensity factor for a plane crack under normal pressure, International Journal of Fracture, 15 (3), 247–258. [6] Wen, P.H., Aliabadi, M.H., Rooke, D.P. (1998). Mixed-mode weight functions in three-dimensional fracture mechanics: static, Engineering Fracture Mechanics 59(5), pp 563–575. [7] Hobbacher, A. (1995). Recommendation on fatigue of welded components, IIW Document XIII-1539- 95/XV-845-95. [8] Gurney, T.R. (1991). The fatigue strength of transverse fillet welded joints. Abington Publishing, Abington, Cambridge [9] Maddox, S.J. (1987). The effect of plaste thickness on the fatigue strength of fillet welded joints. Abington Publishing, Abington, Cambridge. [10] Livieri, P., Segala, F. (2012). Evaluation of Stress Intensity Factors from elliptical notches under mixed mode loadings. Engineering Fracture Mechanics, 81, pp. 110–119 T