Issue 41

M.V.C Sá et alii, Frattura ed Integrità Strutturale, 41 (2017) 90-97; DOI: 10.3221/IGF-ESIS.41.13 90 Focused on Multiaxial Fatigue Notched multiaxial fatigue of Al7050-T7451: on the need for an equivalent process zone size M.V.C Sá Department of Mechanical Engineering, Faculty of Technology, University of Brasília, Brazil Federal Institute of Brasília, Brasília, Brazil marcuscsa@gmail.com J.L.A Ferreira, C.R.M da Silva 2 Federal Institute of Brasília, Brasília, Brazil jorge@unb.br cosmeroberto@unb.br J.A. Araújo Department of Mechanical Engineering, Faculty of Technology, University of Brasília, Brazil jaaunb@gmail.com , alex07@unb.br A BSTRACT . The aim of this work is to investigate stress gradient effects on the fatigue life estimation of notched Al 7050-T7451 specimens under combined torsion and push-pull loading conditions. Initially, simple push-pull and torsion fatigue tests in plain and notched specimens were independently conducted not only to obtain the material properties necessary to calibrate a standard multiaxial critical plane based model, but also to raise the critical distance versus life curves in tension ( L  – N f ) and in torsion ( L  – N f ). This latter step also required a Finite Element Elastic Stress Analysis of the notched specimens tested in the medium high-cycle fatigue regime. Then, proportional multiaxial fatigue tests were carried out using this same notched geometry. The combination of a multiaxial model with the theory of critical distance (TCD) was applied to estimate fatigue lives. For this aluminium alloy, neither the use of the L  – N f nor L  – N f combined with the predictive multiaxial model was able to estimate lives in an accurate way. K EYWORDS . Multiaxial fatigue; Notched fatigue; stress gradient; Process zone; Critical distance; Al 7050-T7451. Citation: Sá, M.V.C., Ferreira, J.L.A., Silva, C.R.M., Araujo, J.A., Notched multiaxial fatigue of Al7050-T7451: on the need for an equivalent process zone size, Frattura ed Integrità Strutturale, 41 (2017) 90-97. Received: 28.02.2017 Accepted: 15.04.2017 Published: 01.07.2017 Copyright: © 2017 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.