PSI - Issue 17

Available online at www.sciencedirect.com Structural Int grity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 17 (2019) 300–307

ICSI 2019 The 3rd International Conference on Structural Integrity Fatigue Behavior of AA2198 in Liquid Hydrogen Jürgen Bär a *, Alexander Metzger a , Nico Pouvesle b , Bernhard Strauß b , Nathan Bamsey c , Thomas Rohr c a University of the Bundeswehr Munich, Institute for Materials Science, D-85577 Neubiberg, Germany b ET EnergieTechnologie GmbH, Eugen-Sänger-Ring 12, D-85649 Brunnthal, Germany c ESA-ESTEC, Keplerlaan 1 12, 2200 AG Noordwijk ZH, The Netherlands ICSI 2019 The 3rd International Conference on Structural Integrity Fatigue Behavior of AA2198 in Liquid Hydrogen Jürgen Bär a *, Alexander Metzger a , Nico Pouvesle b , Bernhard Strauß b , Nathan Bamsey c , Thomas Rohr c a University of the Bundeswehr Munich, Institute for Materials Science, D-85577 Neubiberg, Germany b ET EnergieTechnologi GmbH, Eugen-Sänger-Ring 12, D-85649 Brunnthal, Germany c ESA-ESTEC, Keplerlaan 1 12, 2200 AG Noordwijk ZH, The Netherlands Tensile and fatigue tests were performed on an AA2198 aluminum alloy in the T851 condition in ambient air and liquid hydrogen (LH2). All fatigue tests were performed under load control at a frequency of 20 Hz and a stress ratio of R=0.1. The Gecks-Och Function [1] was fitted on the measured cyclic lifetimes. The tensile strength in LH2 was measured to be 46 % higher compared to the value determined at ambient conditions and the fatigue limit was increased by approximately 60 %. Both S-N curves show a distinct S-shape but also significant differences. Under LH2 environment the transition from LCF- to HCF-region as well as the transition to the fatigue limit is shifted to higher cyclic lifetimes compared to ambient test results. The investigation of the crack surfaces showed distinct differences between ambient and LH2 conditions. These observed differences are important factors in the fatigue behavior change. Tensile and fatigue tests ere erf r ed o an AA2198 aluminum alloy in the T851 condition in ambient air and liquid hydrogen (LH2). All fatigue tests were performed under load control at a frequency of 20 Hz and a stress ratio of R=0.1. The Gecks-Och Function [1] was fitted on the measured cyclic lifetimes. The tensile strength in LH2 was measur d to be 46 % higher compared to the value det rmined at ambient conditions and the fatigue limit was increased by appr ximately 60 %. Both S-N curves show a distinct S-shape but also significant differences. Under LH2 envir nment the transition from LCF- to HCF-region as well as the transition to the fatigue limit is shifted to higher cyclic lifetimes mpared to ambient test results. The investigatio of the crack surfaces showed disti ct differences between ambient and LH2 conditions. These observed differences are important factors in the fatigue behavior change. Abstract Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. Keywords: Aluminium Alloy, Cryogenic Conditions, Failure, Fatigue Keywords: Aluminium Alloy, Cryogenic Conditions, Failure, Fatigue

1. Introduction 1. Introduction

Today, design requirements and cost targets require a better knowledge about material properties and behavior. Especially in challenging technical fields, the knowledge about material properties is a key issue to achieve design Today, design requirements and cost targets require a better knowledge about material properties and behavior. Especially in challenging technical fields, the knowledge about material properties is a key issue to achieve design

* Corresponding author. Tel.: +49-89-6004-2561; fax: +49-89-6004-3055. E-mail address: juergen.baer@unibw.de * Correspon ing author. Tel.: +49-89-6004-2561; fax: +49-89-6004-3055. E-mail address: juergen.baer@unibw.de

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.040