PSI - Issue 19

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000

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ScienceDirect

Procedia Structural Integrity 19 (2019) 405–414

Fatigue Design 2019 Comparison of several methods for the notch effect quantification on specimens from 2124-T851 aluminum alloy Jan Papuga a,b, *, Adam Karkulín a , Ondřej Hanžl a , Maxim Lutovinov a a U12111, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 166 07 Prague 6, Czech Republic b Dept. of Instrumentation and Control Engineering, Faculty of Mechanical Engineering, Center of Advanced Aerospace Technology, Czech Technical University in Prague, Technicka Street 4, 16607, Prague 6, Czech Republic Abstract The paper summarizes several approaches on implementing the notch effect into the fatigue life estimate in high-cycle fatigue region in case of uniaxial fatigue experiments on notched bar specimens. Results of own experiments on specimens prepared from 2124-T851 aluminum alloy (five different notch geometries) are used for the subsequent analyses. The nominal solution derived from the stress concentration factors is compared with the stress gradient approach and the critical distance approach. Fatigue Design 2019 Comparison of several methods for the notch effect quantification on specimens from 2124-T851 aluminum alloy Jan Papuga a,b, *, Adam Karkulín a , Ondřej Hanžl a , Maxim Lutovinov a a U12111, Faculty of Mechanical Engineering, Czech Technical University in Prague, T chnická 4, 166 07 P ague 6, Czech Republic b Dept. of Instrumentation and Control Engineeri g, F c lty of Me h nical Engineering, Center of Advanced Aerospace Technology, Czech Technical University in Prague, Technicka Street 4, 16607, Prague 6, Czech Republic Abstract The paper summarizes several approaches on implementing the notch effect into the fatigue life estimate in high-cycle fatigue region in case of uniaxial fatigue exp riments on notched bar specim ns. Results of own experiments on sp cimens prepared from 2124-T851 aluminum alloy (five different notch geometries) are used for the subsequent analyses. The nominal solution derived from the stress concentration factors is compared with the stress gradient approach and the critical distance approach.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers.

Keywords: notch effect; 2124-T851 aluminum alloy; relative stress gradient; theory of critical distance; high-cycle fatigue Keywords: notch effect; 2124-T851 aluminum alloy; relative stress gradient; theory of critical distance; high-cycle fatigue

1. Introduction The article is focused on applying three approaches: the nominal stress approach (NOM), the stress gradient approach (RSG) and the critical distance approach (TCD) for the fatigue strength estimation of notched specimens. Latter two approaches were developed to estimate the fatigue life of notched components, if the component shape is complex, and the finite element (FE) analysis is therefore used to provide the primary input of local stresses. Automated processing of stress data from the FE-analysis does not favor the nominal stress solution based on the stress concentration factor K t being transformed to the notch factor K f , which decreases the fatigue limit of the original material. The simplest method – the direct use of the maximum stress at the notch root in the fatigue life estimation 1. Introduction The article is focused on applying three approaches: the nominal stress approach (NOM), the stress gradient approach (RSG) and the critical distance approach (TCD) for the fatigue strength estimation of notched specimens. Latter two approaches were developed to estimate the fatigue life of notched components, if the component shape is complex, and the finite element (FE) analysis is therefore used to provide the primary input of local stresses. Automated processing of stress data fro the FE-analysis does not favor the nominal stress solution based on the stress concentration factor K t being transformed to the notch factor K f , which decreases the fatigue limit of the original material. The simplest method – the direct use of the maximum stress at the notch root in the fatigue life estimation

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. * Correspon ing author. Tel.: +420-737-977-741; fax: +420-233-322-482. E-mail address: jan.papuga@fs.cvut.cz, papuga@pragtic.com * Corresponding author. Tel.: +420-737-977-741; fax: +420-233-322-482. E-mail address: jan.papuga@fs.cvut.cz, papuga@pragtic.com

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 10.1016/j.prostr.2019.12.044