Issue 51

N. Benachour et alii et alii, Frattura ed Integrità Strutturale, 51 (2020) 45-51; DOI: 10.3221/IGF-ESIS.51.04

The obtained results are in good agreement with those in the literature [15-18] for the same material and remain in the validity domain of the results in endurance tests for the same material (Al-alloy 2024 T351).

700

Actual criterion Pompetzki et al, [18] Jurcevic et al. [17] Zheng [15] Ngiau & Kujawski [16]

600

500

400

300

y = 2761.1x -0.209 R 2 = 0.97

Opening stresses (MPa)

200

100

1.0E+03

1.0E+06

Number of crack initiation cycles Ni

Figure 6: Crack initiation criterion.

C ONCLUSION

T

he present investigation is conducted in order to evaluate the of fatigue crack initiation criterion in the 2024 T351 Al-alloy. Numerical and analytical approaches were applied to evaluate the stress distribution in Four V-notched specimens. From this investigation, we can conclude that:  The fatigue crack initiation lifetime increases in decreasing of the amplitude loading (i.e. mean loading).  The opening stresses determined numerically are validated analytically and depends on the level of applied load  A fatigue crack initiation criterion at notch root for 2024 T351 Al-alloy showed the advantages in many applications. This criterion gives a satisfactory in prediction of fatigue crack initiation lifetimes comparatively to others published results.

A CKNOWLEDGMENTS

T

he authors gratefully acknowledge the technical support from the: Centre des Matériaux d’Evry – Ecole des Mines de Paris, France. Authors also with to express their gratitude to Professor emeritus André Pineau for fruitful discussions on fatigue crack growth and assistance in fatigue crack growth tests.

R EFERENCES

[1] Heckel, F., Warner, R., (1975), The tensile fatigue behavior of CT specimens with small notch root radius. International Journal of Fracture Mechanics 11, pp. 135-140. DOI : 10.1007/BF00034720. [2] Suresh, S., Ritchie, R.O. (2013). Propagation of short fatigue cracks. International Metals Reviews, 29(6), pp. 446- 475, DOI: 10.1179/imtr.1984.29.1.445.

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