PSI - Issue 43

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2022) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2022) 000 – 000

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Procedia Structural Integrity 43 (2023) 53–58

© 2023 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 MSMF10 organizers. © 20 23 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under the responsibility of MSMF10 organizers. Abstract The prediction of a spatial fatigue crack devel pment under rbitrary loading conditions is a compl x probl m. This paper introduces a new approac to predict crack initiati n and propagation development based on damage theory. The fatigu degradation of the material within a physi ally small volume is described by the kinetic equation for amage function. The mechanical prop rties of the material (elastic moduli) epend n t damage f nction value. Th uniform descriptions of the left and right branches of the full SN-c rve allow the introd ction of the general num rical proc dure f fatigue ranges from HCF to VHCF. At the i itial stage, the values f the damag fu ction are calc lated based on the elastic or lastic-plastic solution. The damage function is ass ciated with two differ nt mechanisms of fatigu d mage accu ulations. The first ne is due to normal tress d the second e is due to sh ar. The contribution of each mec anis to da age function development is calcula ed simultaneously. As soon as the damage function g ts the critical value the omin nt mechanism is established. Therefore, the proposed multi regime odel and numerical procedure are capable to predict crack initiation, spatial crack propagation and dominant crack opening mechanism at different stages of crack growth. © 20 23 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under the responsibility of MSMF10 organizers. 10th International Conference on Materials Structure and Micromechanics of Fracture Multi-regime fatigue failure model based on damage theory Nikitin A.D.*, Nikitin I.S., Stratula B.A. Institute of Computer Aided Design of RAS, 2-nd Brestskaya str., 19/18, Moscow, 123056, Russia Abstract The prediction of a spatial fatigue crack development under arbitrary loading conditions is a complex problem. This paper introduces a new approach to predict crack initiation and propagation development based on damage theory. The fatigue degradation of the material within a physically small volume is described by the kinetic equation for damage function. The mechanical properties of the material (elastic moduli) depend on the damage function value. The uniform descriptions of the left and right branches of the full SN-curve allow the introduction of the general numerical procedure for fatigue ranges from HCF to VHCF. At the initial stage, the values of the damage function are calculated based on the elastic or elastic-plastic solution. The damage function is associated with two different mechanisms of fatigue damage accumulations. The first one is due to normal stress and the second one is due to shear. The contribution of each mechanism to damage function development is calculated simultaneously. As soon as the damage function gets the critical value the dominant mechanism is established. Therefore, the proposed multi regime model and numerical procedure are capable to predict crack initiation, spatial crack propagation and dominant crack opening mechanism at different stages of crack growth. 10th International Conference on Materials Structure and Micromechanics of Fracture Multi-regime fatigue failure model based on damage theory Nikitin A.D.*, Nikitin I.S., Stratula B.A. Institute of Computer Aided Design of RAS, 2-nd Brestskaya str., 19/18, Moscow, 123056, Russia 1. Introduction The fatigue failure is complex process of material degradation under cyclic loading comprising several distinguished steps at different scales. The crack initiation is associated with an irreversible changing at the microscopic level. Depending on the stress state the crack initiation constitutes a significant fraction of the total fatigue life. The crack initiation stage is longer for low stress amplitudes. The second step of the fatigue failure is crack 1. Introduction The fatigue failure is complex process of material degradati n un er cyclic loading comprising several distinguished steps at different scales. The crack initiation is associated with an irreversible changing t th microscopic level. Depe din on the stress state the crack initiation constitutes a significant fraction of the total fatigue life. The crack initiation stage is longer for low stress amplitudes. The second step of the fatigue failure is crack Keywords: fatigue, damage function, mathematical modeling, numerical simulation, life prediction. Keywords: fatigue, damage function, mathematical modeling, numerical simulation, life prediction.

* Corresponding author. Tel.: +7-965-436-59-80. E-mail address: nikitin_alex@bk.ru * Correspon ing author. Tel.: +7-965-436-59-80. E-mail address: nikitin_alex@bk.ru

2452-3216 © 2023 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 MSMF10 organizers. 2452-3216 © 2023 The Authors. Published by Elsevier B.V. This is an ope access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of MSMF10 organizers.

2452-3216 © 2023 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 MSMF10 organizers. 10.1016/j.prostr.2022.12.234