PSI - Issue 54

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000

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ScienceDirect

Procedia Structural Integrity 54 (2024) 369–375

International Conference on Structural Integrity 2023 (ICSI 2023) Damage accumulation and fracture of polymer composites under preliminary biaxial cyclic loading

Artur Kuchukov a *, Oleg Staroverov a , Artur Mugatarov a a Perm National Research Polytechnic University, Komsomolsky prospekt 29, 614990 Perm, Russia

© 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 the scientific committee of the ICSI 2023 organizers Abstract The paper presents the results of experimental study of mechanical behavior of thin-walled tubular fiberglass samples obtained by continuous winding under proportional tension-torsion loading. The decrease in static strength after cyclic loading of different durations has been estimated. Tensile, torsion and proportional tensile-torsion tests with different variations of the normal and shear components of the stress tensor are realized. During torsion, the diagram was non-linear; the presence of a stage similar to plastic was noted. A significant decrease in fatigue life under biaxial loading compared to uniaxial tensile or torsional loading was observed. The influence of the stress state type under preliminary cyclic loading on the residual mechanical characteristics was noticed. Microstructural analysis was carried out, the effect of the preliminary cyclic loading mode and duration on the surface type of the samples was noted. It is concluded that this approach is promising and that it is rational to conduct further experimental studies to verify the previously developed models. © 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 the scientific committee of the ICSI 2023 organizers Keywords: composite, tubular specimen, damage accumulation, fatigue sensitivity, multiaxial loading, residual stiffness. 1. Introduction A lot of works is devoted to the problems of change of residual strength and stiffness characteristics of polymer composite materials under uniaxial cyclic loading [1-5]. However, in practice, composite material structures are under complex stress-strain condition due to the presence of multiaxial loads such as tensile with torsion, bending. Based on this, the study of composite mechanical behavior under multiaxial cyclic loading seems to be an important mechanical problem. Dependencies of changes in residual strength and stiffness characteristics of the studied composites on cyclic lifetime can be conveniently interpreted in the form of fatigue sensitivity diagrams [6]. These curves indicate typical stages or sections: I - initiation stage, when at a comparatively small number of cycles there is a quick decrease of

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 the scientific committee of the ICSI 2023 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 the scientific committee of the ICSI 2023 organizers 10.1016/j.prostr.2024.01.095