PSI - Issue 41

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

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 41 (2022) 232–240

© 2022 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 MedFract2Guest Editors. Abstract The study analyzed the fatigue tests of GFRP laminates [0/(±45)2/0 ] T of specimens cut at different angles (0°, 30°, 45°, 60°, 90°) in relation to the axis 0. The value of the equivalent stress has been determined according to two popular criteria taken from statics. Assuming the parallelism of the basic fatigue characteristics of the specimens cut at 0° and 90° and defining the values of X , Y and S, which are maximum values of stress in different directions, we modified criteria proposed by Azzi-Tsai-Hill and by Norris. Due to the fact that these criteria are nonlinear due to the components of the stress state, they cannot be applied to operational or non conforming loads in phase. Therefore, it is proposed to apply a linear relationship for the components of the stress state in the form of the following expression for the equivalent normal stress in the critical plane defined by this stress. As a result, the obtained amplitudes of equivalent stresses were compared with the experimental fatigue life. It has been shown that the newly proposed criterion for reduced stress, can be successfully applied to composite materials. © 2022 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) un li 2nd Mediterranean Conference on Fracture and Structural Integrity Fatigue lifetime of GFRP laminates in critical plane defined by equivalent normal stress Karolina Głowacka a *,Tadeusz Łagoda a a Opole University of Technology, ul.Mikołajczyka 5, 45 -271 Opole, Poland

Peer-review under responsibility of the MedFract2Guest Editors. Keywords: Composite materials; multiaxial fatigue; failure criteria

1. Introduction The basic strength properties of all materials are determined in simple load states. However, very often in practice we deal with a complex state of stress. For this purpose, numerous authors propose various strength criteria and, as a

* Corresponding author. Tel.: +48 774498459. E-mail address: k.glowacka@po.edu.pl

2452-3216 © 2022 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 MedFract2Guest Editors.

2452-3216 © 2022 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 MedFract2Guest Editors. 10.1016/j.prostr.2022.05.026