PSI - Issue 19

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

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Procedia Structural Integrity 19 (2019) 370–379

Fatigue Design 2019 Fatigue characterization of embedded layers in CFR Composites Christian Schneider a,* , Matthias Drvoderic b , Gerald Pinter a , Clara Schuecker b , Christian Gaier c Fatigue Design 2019 Fatigue characterization of embedded layers in CFR Composites Christian Schneider a,* , Matthias Drvoderic b , Gerald Pinter a , Clara Schuecker b , Christian Gaier c a Chair of Material Science and Testing of Polymers, Montanuniversität Leoben, 8700 Leoben, Austria b Chair of Designing Plastics and Composite Materials, Montanuniversität Leoben, 8700 Leoben, Austria c Magna Powertrain, Engineering Center Steyr, 4300 St. Valentin, Austria a Chair of Material Science and Testi of Polymers, Montanuniversität Leobe , 8700 Leoben, Austria b Chair of Designing Plastics and Composite Materials, Montanuniversität Leoben, 8700 Leoben, Austria c Magna Powertrain, Engineering Center Steyr, 4300 St. Valentin, Austria The stress-based approach with experimental S/N curves (stress amplitude vs. number of cycles) is a well-known approach for lifetime prediction of components, also in the composite industry. The problem with this so called "Wöhler" approach is that only final fatal failure of specimen can be described. But for a real definition of end-of lifetime the identification of failure mechanisms and the corresponding sequence of effects are essential. Besides that for embedded layers, the initiation of first cracks does not lead to failure of the whole specimen. Within this work two different layups with carbon fibre reinforced polymers in UD 90° respectively embedded UD 90° within UD 0° direction was used. Starting from these two layups, a simulation was done for different end tab-materials and several taper angles to get an overview on the lowest risk factor for breakage at the tab/specimen transition region of the specimen. Regarding the simulation results, specimens were produced and different end tabs were added. Quasi-static as well as fatigue tests were performed and compared based on the calculation with classical laminate theory. Also a comparison between simulation and testing of the crack region for the UD 90° specimen was done. With this work, a base for further variation of specimen geometry was established to monitor the initiation and propagation of (micro-)cracks in the embedded UD 90° layers with different techniques . Abstract The stress-based approach with experimental S/N curves (stress amplitude vs. number of cycles) is a well-known approach for lifetime prediction of components, also in the composite industry. The problem with this so called "Wöhler" approach is that only final fatal failure of specimen can be described. But for a real definition of end-of lifetime the identification of failure mechanisms and the corresponding sequence of effects are essential. Besides that for embedded layers, the initiation of first cracks does not lead to failure of the whole specimen. Within this work two different layups with carbon fibre reinforced polymers in UD 90° respectively embedded UD 90° within UD 0° direction was used. Starting from these two layups, a simulation was done for different end tab-materials and several taper angles to get an overview on the lowest risk factor for breakage at the tab/specimen transition region of the specimen. Regarding the simulation results, specimens were produced and different end tabs were added. Quasi-static as well as fatigue tests were performed and compared based on the calculation with classical laminate theory. Also a comparison between simulation and testing of the crack region for the UD 90° specimen was done. With this work, a base for further variation of specimen geometry was established to monitor the initiation and propagation of (micro-)cracks in the embedded UD 90° layers with different techniques . Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. P er-review under responsibility of the Fatigu Design 2019 Organizers.

Keywords: unidirectional; transvers; cross ply; embedded; simulation; Puck criterion; tabs; taper angle; CFRP; tensile test; lifetime prediction; fatigue; Wöhler approach; Keywords: unidirectional; transvers; cross ply; embedded; simulation; Puck criterion; tabs; taper angle; CFRP; tensile test; lifetime prediction; fatigue; Wöhler approach;

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers.

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 10.1016/j.prostr.2019.12.040