PSI - Issue 46

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2021) 000–000

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 46 (2023) 69–74

© 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 responsibility of ICSID 2021 Organizers Abstract This paper deals with plastic constraint at a crack tip. The finite element model (FEM) of a middle-crack tension (M(T)) specimen was used for the analysis of plastic zone and determination of the constraint factor. The elastic–perfectly plastic material model was utilized to characterize aluminium alloy. The global constraint factor α gS over the specimen thickness was determined from the region of the plastically deformed material in the middle plane of a crack. The constraint factor is used as the input for the strip yield model (SYM) of the crack to characterize stress state at a crack tip. Crack opening displacements (COD) of both, FEM and SYM were compared to each other. It is shown that SYM yields good match in comparison to FEM data when using FEM-based constraint factor α gS under both, plane strain and plane stress conditions. Moreover, the dependence of the constraint factor α gS on the ratio of thickness over the squared plastic zone size was found. The semi-log plot shows the tendency to form uniform trend. © 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) 1. Introduction Fatigue analyses are carried out to identify the mechanism of failures or to predict service life as illustrated in Pastorcic (2019) or Braut (2021). Modern approach to parts design according to damage tolerance philosophy demands higher focus on the stage of crack growth; i.e. Schijve (2001) and Dirika (2018). The influence of a part thickness on the crack growth in metallic materials is well known phenomena (Schijve (2001)). The thickness effect appears mostly under variable amplitude loading (VAL) as shown in Mills (1975) or Ruzek (2017). During VAL 5th International Conference on Structural Integrity and Durability, ICSID 2021 Constraint definition at a crack tip for the strip yield model Jakub Šedek a * a Czech Aerospace Research Centre, Beranových 130, 19905, Prague – Let ň any, Czech Republic Peer-review under responsibility of ICSID 2021 Organizers. Keywords: COD; constraint; crack growth; FEM; strip yield model

* Corresponding author. Tel.: +420 225 115 127. E-mail address: sedek@vzlu.cz

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 ICSID 2021 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 responsibility of ICSID 2021 Organizers 10.1016/j.prostr.2023.06.013