PSI - Issue 17

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

www.elsevier.com/locate/procedia

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ScienceDirect

Procedia Structural Integrity 17 (2019) 254–261

ICSI 2019 The 3rd International Conference on Structural Integrity Analysis of the crack location in notched steel bars with a multiple DC potential drop measurement Moritz Hartweg, Jürgen Bär* University of the Bundeswehr Munich, Institute for Materials Science, D-85577 Neubiberg, Germany ICSI 2019 The 3rd International Conference on Structural Integrity Analysis of he crack l cation in notched st el bars with a multiple DC potential drop measurement Moritz Hartweg, Jürgen Bär* University of the Bundeswehr Munich, Institute for Materials Science, D-85577 Neubiberg, Germany

Abstract

Abstract

The direct current potential drop (DCPD) technique is a frequently used method to measure crack propagation in metallic materials. With a single potential probe attached to the specimen, the size of an initiated crack can be estimated. Therefore, this method is used in crack propagation experiments to determine the crack propagation rate. However, with a single potential probe it is difficult to detect small cracks and impossible to determine the location of the initiated crack. In the present study, three potential probes were attached to cyclic loaded notched steel bars. For the case of an initiated single crack, this experimental set-up delivers different potentials depending on the distance of the probe to the initiated crack. A geometric model to determine the position of the initiated crack from the increase of the individual probe signals is presented. The experimental verification of the model has shown that in case of a single crack, the position can be determined clearly, even in the early stages of crack propagation. Moreover, the sensitivity of the potential drop measurement for the detection of an initiated crack is enhanced by this method. In case of multiple crack initiation sites the scatter of the calculated angle can be used as a criterion for crack detection. The direct current potential drop (DCPD) technique is a frequently used method to measure crack propagation in metallic materi l . With a single pot ntial probe attach d to the specimen, the size of an initiated crack can be estimated. Therefore, this method is used in crack propagation experiments to determine the crack propagation rate. However, with a single potential probe it is difficult to detect small cracks and impossible t determine the location of th initiated crack. I the present study, three potential prob s were attached to cyclic loaded notched steel bars. For the case of a initiated singl crack, this xperimental set-up delivers different potentials depending on the distance of the probe to the initiated crack. A geometric m del to determine t e position of th initiated cra k from the increase of the individual probe signals is presented. The experimental verification of the model has shown that in case of a single crack, the positi can be determined cl arly, even in the early stages of cra k p opagation. Moreover, the sensitivity of the potential drop measurement for the detection of an initiated crack is enhanced by this method. In case of multiple crack initiation sites the scatter of the calculated angle can be used as a criterion for crack detection.

© 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. P er-review u der res onsibility of the ICSI 2019 org nizers. Keywords: Potential Drop Method, Crack Position Determination, Fatigue; Crack Initiation

Keywords: Potential Drop Method, Crack Position Determination, Fatigue; Crack Initiation

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. * Corresponding author. Tel.: +49-89-6004-2561; fax: +49-89-6004-3055. E-mail address: ju rgen.baer@ nibw. e * Corresponding 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. 10.1016/j.prostr.2019.08.034