PSI - Issue 57

J. Torggler et al. / Procedia Structural Integrity 57 (2024) 152–160

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000

© 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 Fatigue Design 2023 organizers Keywords: Cord rubber composite; Fatigue testing; Tomography; Delamination; Damage Assessment; 1. Introduction Cord rubber composites are used in many areas, such as tyres, hoses and air suspension bellows for cars, trucks, and rail vehicles. The task of this components is mostly relevant for the operation and therefore a safe operation is utmost important. In most cases, the component in which the material is used is subjected to repeated cyclical loads may facilitating fatigue failure under in-service conditions. In this study the focus is laid on the cord rubber composite material of the air spring bellow in rail vehicles. For the static calculation of this constructions, there are several approaches and possibilities in the literature, e.g. Carsten (1995), Pelz et al. (2007), Donner (2017). However, for the service life testing and calculation of the fibre composite material there are only few reference points, see Kenney et al. (1985), Liu Yu et al. (1999), Cho et al. (2015), Frankl et al. (2019). The layup, materials used and the load situation in the composite are mostly application-specific and hence, a general statement is rarely possible. In other areas component tests are used to estimate the durability , such as Wode (1995), Polley (1999), Oman et al. (2010), Förster (2012), Oman and Nagode (2013), Bešter et al. (2014) . But this approach is significantly time-consuming and cost-intensive, especially for air springs on rail vehicles. These large components exhibit a long service life (six to twelve years) and are manufactured in comparatively (to automotive application for example) small quantities and partly manually. For these reasons, the analysis of the fatigue damaging effects at sample level is particularly useful in this case. There are several approaches already known on this field. Most of them are very specific investigations of local effects, without considering the layup, such as Pidaparti (1997), Rao et al. (2004), Shi et al. (2015), Eitzen et al. (2018), Tao et al. (2018). Therefore, the development of a specimen for rail vehicle specific load situations and mechanisms appears reasonable. Based on existing component tests and a finite element simulation model for these components, a sample geometry was developed to investigate the dominant damage mechanisms. The advantage of the specimen is the isolated observation of damage-relevant load conditions for various combinations with different layup. The development of the representative specimen is shown in detail in a previous publication, Torggler et al. (2023). © 2024 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 Fatigue Design 2023 organizers

Nomenclature p i

Internal pressure Lateral displacement

U V

Longitudinal displacement

Lateral Force

F x F y

Longitudinal Force

Fibre length Fibre angle

l

φ f

Logarithmic strain

ε log

Statistically evaluated scatter band

T s P s

Probability of survival Number of load-cycles

N