Issue 51

N. Benachour et alii, Frattura ed Integrità Strutturale, 51 (2020) 45-51; DOI: 10.3221/IGF-ESIS.51.04 45 Focussed on Structural Integrity and Safety: Experimental and Numerical Perspectives Experimental investigation of fatigue crack initiation from notches in 2024 T351 Al-alloy Nadjia Benachour, Mustapha Benachour* University of Tlemcen, Ingeniery of Mechanical Systems and Materials Laboratory, Tlemcen, Algeria Faculty of Technology, Mechanical Engineering Department nbenachour2005@yahoo.fr , bmf_12002@yahoo.fr Mohamed Benguediab University of Sidi Bel Abbes, LMPM Laboratory, Sidi Bel Abbes (Algeria), Mechanical Engineering Department benguediab_m@yahoo.fr A BSTRACT . In this investigation, fatigue crack initiation criterion was established from notches in aged hardening aluminum alloy. This criterion was used to predict the residual lifetime in aeronautical structures subjected to constant amplitude loading using concept of local stress at notch. Charpy V- notch specimens were taken from sheet plate and the notch radius accurately machined at value of 0.2mm. The local stresses were determined numerically and validated analytically. In experimental investigation, the V-notched specimens were loaded in four point bending fatigue with a stress ratio R=0.1 and variation in amplitude loading. K EYWORDS . Fatigue crack initiation; Notch; Finite element method; Stress field; Aluminum alloy. Citation: Benachour, N., Benachour, M., Benguediab, M., Experimental investigation of fatigue crack initiation from notches in 2024 T351 Al-alloy, Frattura ed Integrità Strutturale, 51 (2020) 45-51. Received: 04.05.2019 Accepted: 12.10.2019 Published: 01.01.2020 Copyright: © 2020 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION enerally, aeronautical structures are subjected to cyclic loading. Discontinuities and notches in mechanical components and structures present a site of stress concentration resulting of external load that could be sites of crack initiation. The fatigue life of structural components is determined by the sum of the numbers cycles required to initiate a fatigue crack and to propagate this crack up to the critical dimension. Many approaches may be classified in different manner to analyses fatigue crack initiation from notch. The global elastic analysis, it takes into account linear fracture mechanics. Firstly, this approach was sued by Heckel et al. [1] by introducing the loading parameter (  K/  1/2).  K is the amplitude loading of stress intensity factor and  is the radius of the tip of notch. This approach was used by some researchers. Suresh and Ritchie [2] have applied this approach for some alloys (steel and Al-alloy). Also Bauss [3] and DuQuesnay [4] have used this approach respectively for high strength steel, 2024 T351 Al-alloy and SAE 1045 steel. These authors noted that this correlation for small numbers of cycles at radius notch les than critical value does G