PSI - Issue 75

ScienceDirect Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia (2025) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia (2025) 000 – 000 Available online at www.sciencedirect.com

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 75 (2025) 289–298

© 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of Dr Fabien Lefebvre with at least 2 reviewers per paper Abstract Results of three different types of solution, which estimate the fatigue strength of notched specimens are described. S-N curves of seven specimen configurations (from which five are notched) are analysed each for three separate load modes – push-pull, torsion and plane bending – at fully reversed loading. This input is processed by various versions of the relative stress gradient method, two versions of the theory of critical distances and by a new method based on the critical volume concept. Quality of the output favours the relative stress gradient solution, while the new critical volume solution shows slightly worse prediction. TCD application shows worse estimates due to invariant critical distance for notches of significantly varying acuity. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2025 organizers Keywords: Type your keywords here, separated by semicolons ; 1. Introduction Fatigue stress-life estimation addresses the effects mentioned in the title differently. The load effect differentiates among various loading modes that lead to uneven stress distributions across the critical cross-section. The notch effect accounts for this uneven stress distribution when induced by structural irregularities. Conversely, the size effect – sometimes referred to as the “statistical” size effect – addresses the weak-link mechanism of fatigue damage, Fatigue Design 2025 (FatDes 2025) Load effect, notch effect, size effect, and other related factors in the stress-based fatigue estimation – is there a way to unite them? Jan Papuga a,* , Leonardo Serri b , Martin Nesládek a , František Fojtík c , Tomáš Petkov c , Petr Vaněk a a Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 166 07 Prague 6, Czechia b Department of Industrial Engineering, University of Padova, Via Venezia 1, 35131 Padova, Italy c Faculty of Mechanical Engineering, VŠB -TU Ostrava, 17.listopadu 15, 708 33 Ostrava, Czechia Abstract Results of three different types of solution, which estimate the fatigue strength of notched specimens are described. S-N curves of seven specimen configurations (from which five are notched) are analysed each for three separate load modes – push-pull, torsion and plane bending – at fully reversed loading. This input is processed by various versions of the relative stress gradient method, two versions of the theory of critical distances and by a new method based on the critical volume concept. Quality of the output favours the relative stress gradient solution, while the new critical volume solution shows slightly worse prediction. TCD application shows worse estimates due to invariant critical distance for notches of significantly varying acuity. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2025 organizers Keywords: Type your keywords here, separated by semicolons ; 1. Introduction Fatigue stress-life estimation addresses the effects mentioned in the title differently. The load effect differentiates among various loading modes that lead to uneven stress distributions across the critical cross-section. The notch effect accounts for this uneven stress distribution when induced by structural irregularities. Conversely, the size effect – sometimes referred to as the “statistical” size effect – addresses the weak-link mechanism of fatigue damage, Fatigue Design 2025 (FatDes 2025) Load effect, notch effect, size effect, and other related factors in the stress-based fatigue estimation – is there a way to unite them? Jan Papuga a,* , Leonardo Serri b , Martin Nesládek a , František Fojtík c , Tomáš Petkov c , Petr Vaněk a a Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 166 07 Prague 6, Czechia b Department of Industrial Engineering, University of Padova, Via Venezia 1, 35131 Padova, Italy c Faculty of Mechanical Engineering, VŠB -TU Ostrava, 17.listopadu 15, 708 33 Ostrava, Czechia

* Corresponding author. Tel.: +420 737 977 741 E-mail address: jan.papuga@fs.cvut.cz * Corresponding author. Tel.: +420 737 977 741 E-mail address: jan.papuga@fs.cvut.cz

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2025 organizers 2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2025 organizers

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of Dr Fabien Lefebvre with at least 2 reviewers per paper 10.1016/j.prostr.2025.11.030