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

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Procedia Structural Integrity 17 (2019) 183–189

ICSI 2019 The 3rd International Conference on Structural Integrity DCPD based detection of the transition from short to long crack propagation in fatigue experiments on the aluminum alloy 7475 T761 Meike Funk*, Jürgen Bär University of the Bundeswehr, Intsitute for Material Science, 85577 Neubiberg, Germany ICSI 2019 The 3rd International Conference on Structural Integrity DCPD based detection of the transition from short to long crack propagation in fatigue experiments on the aluminum alloy 7475 T761 Meike Funk*, Jürgen Bär University of the Bundeswehr, Intsitute for Material Science, 85577 Neubiberg, Germany The cyclic lifetime of components can be divided into crack initiation, short crack growth until a through-thickness crack has built up, followed by long crack growth until final failure. For lifetime calculations of technical alloys based on fracture mechanics the calculation normally is limited to the propagation of long cracks. Unfortunately, long crack propagation covers only a minor part of the total lifetime. The propagation of short cracks extends over more than half of the service life and is therefore the focus of a lot of studies. For all calculations and researches an accurate crack length measurement is necessary, especially for short crack growth. With a high-resolution DC potential drop measurement, a crack can be detected very early, but it is not possible to display the real shape and location of the initial crack. Hence, this would be necessary for a full-featured detection of short crack propagation. Attaching multiple DC potential probes near the crack initiation site an analysis of the location and shape of the short cracks is possible. This paper shows the possibilities of short crack detection with two potential probes mounted near the notch on SEN specimens. The cyclic lifetime of components can be divided into crack initiation, short crack growth until a through-thickness cra k has built up, followed by long crack growth until final failure. For lifetime calculations of technic l alloys based on fracture mecha ics the calculation normally is limited to the propagation of long cracks. Unfortunately, l ng crack propagation cov rs nly a minor part of the total lifetime. The propagation of short cracks extends over more than half of the service life and is therefore the focus of a lot of studies. For all calculations and researches an accurate cr ck length m asurement is n cessary, especially for short crack growth. With a high-resoluti n DC potential drop measurement, a crack can be detected very early, but it is not possible to display the real shape and location of the initial crack. Hence, this would be necessary for a full-featured detecti n of short crack propagation. Attaching multiple DC potential probes n ar the crack initiation site an analysis of the location and shape of t short cracks is possibl . This paper shows the possibilities of short crack detection with two potential probes mounted near the notch on SEN specimens. 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: short crack propagation, multiple DCPD, SEN Keywords: short crack propagation, multiple DCPD, SEN

* Corresponding author. Tel.: +49-89-6004-2552; fax: +49-89-6004-3055. E-mail address: meike.funk@unibw.de * Correspon ing author. Tel.: +49-89-6004-2552; fax: +49-89-6004-3055. E-mail address: meike.funk@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.2019.08.025