13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- Ideally, it would be better to deal with high values of ρ because they are easier to machine at the notch tip. In the other hand, the smaller the notch root radius ρ, the greater the maximum non-propagating crack max a is, and, consequently, the more reliably the method can be applied to predict non-propagating cracks that can be robustly measured. According to the numerical results shown in Fig. , for ~1.5 <ρ it can be expected that the maximum non-propagating crack size should be max 0.309 0.83 mm a mm < < . Those values can be easily measured by an optical microscope. 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 a max ρ(mm) Fig. 6 Comparison of predictions of the maximum non-propagating crack amax as a function of the notch root ρ. 4. Conclusions A method was used to predict the notch factor f K and, therefore, the fatigue limit for a notched specimen can be designed to induce non-propagating short cracks at the notch root. The configuration of the notch was approximated as a semi-elliptical notch and its fatigue limit was determined as a function of the radius of the notch root ρ. The largest non-propagating crack length can be calculated. References [1] B. Bhattacharya, B. Ellingwood, Continuum damage mechanics analysis of fatigue crack initiation. Int. J. Fatigue. 20 (1998) 631-639. [2] C. Kaynak, A. Ankara, T.J. Baker, A comparison of short and long fatigue crack growth in steel. Int. J. Fatigue. 18 (2006) 17-23. [3] Frost NE, Marsh KJ,Pook LP. Metal Fatigue, Dover, 1999. [4] J.T.P. Castro, M.A. Meggiolaro, M.A.C. Oliveira, H. Wu, A. Imad, N. Benseddiq, Prediction of fatigue crack initiation lives at elongated notch roots using short crack concepts. Int. J. Fatigue. 42 (2012) 172-182. [5] J. Schijve, Fatigue of Structures and Materials, Kluwer, Dordrecht, 2001. [6] C.E. Inglis, Stresses in a plate due to the presence of cracks and sharp corners. Trans. Inst. Naval Architects., 55(1913) 219-241. [7] M.H. El Haddad, T.H. Topper, K.N. Smith, Prediction of non-propagating cracks. Eng. Fract. Mech. 11(1979) 573-584. [8] Z.P. Bazant, Scaling of quasibrittle fracture: asymptotic analysis. Int. J. Fracture. 83(1997)
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