Experimental analysis and numerical modelling of microcrack induced delaminations under cyclic loading with load reversals
Final Report Abstract
Delaminations between the individual layers of fiber-reinforced plastic composites (FRP) are often caused by inter-fiber failures (IFF). In consequence, the delaminations can quickly spread over large parts of the FRP structure and lead to premature failure. As part of the project, methods, that describe IFF-induced delamination in FRP laminates and aim at the utilization for FE simulations, were developed. For this purpose, quasi-static as well as cyclic DCB and ENF tests were carried out on test specimens with [0/0] and [0/90] layer boundaries and corresponding crack propagation laws were derived. The necessary testing equipment and evaluation methods were developed within the project. In addition, cyclic tests were carried out on laminates with a bidirectional [0/90]s lay-up. The IFF and delaminations that occurred during the test were quantified using automated image analysis developed in the project. Analytical and numerical simulation models of FRP-laminates were used to determine crack propagation laws for IFF-induced delamination processes. These were found to differ significantly from the crack propagation laws obtained by DCB and ENF tests. For the numerical simulation of the IFF-induced delamination processes, different FE models of cross-ply laminates with predefined IFF in the embedded 90° plies were built up. The ply interfaces were modelled by means of a cohesive zone model (CZM). The static traction separation law (TSL) serves as a basis for the CZM and is directly derived from experimental data by means of a newly developed method. The enhancement of the CZM for cyclic loadings is realized using the well-established CF20 model by Dávila.
Publications
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Bruchmechanische Analyse des Delaminationswachstums in glasfaserverstärkten Verbundkunststoffen bei Ermüdungsbelastung, Tagung Werkstoffprüfung 2022, Oktober 2022, S. 6
G. Just; I. Koch; M. Gude; G. Hacker; S. Scheffler & R. Rolfes
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Experimental Analysis of Matrix Cracking in Glass Fiber Reinforced Composite Off-Axis Plies under Static and Fatigue Loading. Polymers, 14(11), 2160.
Just, Gordon; Koch, Ilja & Gude, Maik
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Numerical Simulation of Microcrack-Induced Delamination in Cross-Ply-Laminates under Static Loading Using Cohesive Zone Models, Composites Meet Sustainability - Proceedings of the 20th European Conference on Composite Materials (ECCM20), Lausanne, 2022.
G. Hacker; M. Brod; G. Just; S. Scheffler; I. Koch; R. Rolfes & M. Gude
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Analysis of fatigue crack and delamination growth in GFRP Composites in tension and compression loading, ICFC9 – The 9th International Conference on the Fatigue of Composites, 21 – 23 Juni 2023, Vicenza, Italien
G. Just; I. Koch; G. Hacker; S. Scheffler; M. Gude & R. Rolfes
