Fatigue assessment of cord rubber composite air spring bellows based on specimen testing and numerical analysis

• Published in: Journal of applied polymer science Vol. 141; no. 37
• Main Authors: Torggler, Julian, Faethe, Tobias, Müller, Heiko, Dutzler, Andreas, Machado Charry, Eduardo, Buzzi, Christian, Leitner, Martin
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 05.10.2024; Wiley Subscription Services, Inc
• Subjects: Air springs; Bellows; composites; Correlation coefficients; Cost analysis; Damage assessment; degradation; delamination; fatigue; Fatigue failure; Fatigue strength; Fatigue tests; fibers; Internal pressure; mechanical properties; Numerical analysis; Numerical models; Pressure drop; Rubber; specimen tesing; Tensile stress
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.55949

Rail vehicle air spring bellows consisting of cord rubber composites are subject to a wide variety of stresses. It is therefore crucial to understand the fatigue behavior of such components, as the development process involves the use of empirical methods, which are both time‐consuming and costly. This paper outlines a methodology for assessing the fatigue strength of air spring bellows through representative specimen testing. Ten component tests and a validated numerical model of the air spring bellows are presented. The primary loading scenario investigated in this study is pure pulsating tensile stress with a strain ratio R in the range of 0–0.25. This scenario is considered to be highly damaging, leading to delamination. Comprehensive damage analysis of the specimen is performed using microcomputed tomography. To ensure the transferability of the results, a failure criterion is defined as 20% elongation of the specimen, based on the defined 10% internal pressure drop for the bellow. After statistical evaluation, the transferability of the specimen tests to the component is validated using a local fatigue approach. The correlation coefficient R2 is 0.84, indicating a sound agreement between model and tests with 7 points out of 10 within a scatter factor of 2. This paper presents a thorough examination of the fatigue performance of cord rubber composites. The investigation includes an analysis of component tests and a specially developed methodology for testing representative specimens. Furthermore, a novel approach is employed to study the transferability of small‐scale specimens to the component level for rail vehicle air spring bellows.