PSI - Issue 33

Available online at www.sciencedirect.com

Available online at www.sciencedirect.com ScienceDirect

Structural Integrity Procedia 00 (2021) 000–000

ScienceDirect

www.elsevier.com/locate/procedia

Procedia Structural Integrity 33 (2021) 1115–1122

IGF26 – 26 International Conference on Fracture and Structural Integrity

Fracture Criteria and Duality of Critical Damage-Failure Transitions

Naimark O.B. 1 , Uvarov S.V. 1 , Nikityuk A.S. 1 , Kirsanov A.R. 2

1 Institute of Continuous Media Mechanics of the Ural Branch of Russian Academy of Science (ICMM UB RAS), Academician Korolev Street, 1 Perm, 614013, Russian Federation 2 A.Lyulka Design Bureau, Kasatkina str., Moscow, 129301, Russian Federation

Abstract

© 2021 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 IGF ExCo Duality of criticality of damage-failure transitions, caused by two intermediate self-similar singular solutions for the stress field at the crack tip (the stress intensity factor criteria) and the blow-up damage localization kinetics, is used for the interpretation of two-parameters fracture criteria. Two additional parameters (cohesive strength and cohesive length) are associated with parameters of the blow-up damage localization kinetics initiated by critical (cohesive) stress at the crack process zone . The presence of two self-similar solutions provides the variety of crack advance depending on the load intensity or the notch type. Two parameters criteria was introduced as the measure of the average stress at the damage localization area (the so called, process zone). The idea of averaging a sharply increasing stress in front of a notch (crack) over a characteristic length with the subsequent comparison of the obtained averaged stress with the ultimate strength of the material was introduced by Novozhilov as stress averaging criterion and modified as the two-parameters criteria. The two stress criteria in the presence of two characteristic lengths allow the interpretation of the Critical Distance approach in terms of mentioned two intermediate self similar singular solutions. Realization of experimental program analyzing the DIC pattern in the stretched notch sample revealed the presence of two attractors (corresponding to two self-similar solutions) responsible for two mechanisms of damage-failure transition related to two-parameters fracture criteria. © 2021 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 Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo Keywords: Gapped Momentum States, defects induced criticality, viscosity limit This is an open access article un

1. Two-parameter fracture mechanics and duality of critical damage-failure transition

The recent studies in fracture mechanics indicate a significant effect on fracture toughness of factors such as geometry, sample thickness and type of crack-like defects. In this regard, the problem arises of transferring the results of the experimental determination of the fracture toughness of samples to the fracture toughness of critically

1 * Corresponding author. Prof.Oleg Naimark Tel.: +7-342-2378-389 ; fax: +7-342-2378-487. E-mail address: naimark@icmm.ru

2452-3216 © 2021 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 XXIIth Winter School on Continuous Media Mechanics”

2452-3216 © 2021 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 IGF ExCo 10.1016/j.prostr.2021.10.124