Fatigue of polymer composites under cyclic thermal loads

• Applicants: Dr. Gerhard Kalinka; Professor Dr.-Ing. Michael Sinapius
• Subject Area: Mechanics ; Lightweight Construction, Textile Technology
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 379482657

• Final Report Year: 2023

Final Report Abstract

Fiber-reinforced plastic composites (FRP) are used as a structural material in cryogenic pressure vessels for hydrogen storage. There, they are exposed to cyclic temperature loads in the cryogenic range, which can lead to material fatigue. Due to the rapid refueling process, local temperature gradients occur in the material. In the project, the fatigue behavior of CFRP under thermal cyclic loading was investigated. The central research hypothesis was that fatigue from cyclic temperature loading occurs at multiple scale levels due to intra- and interlaminar residual stresses. These residual stresses are caused by the differential thermal expansion of fiber and matrix at the micro-scale and by the differential thermal expansion of adjacent plies of different fiber orientation in a multilayer laminate at the macro-scale. The thermal stress can be described by an equivalent mechanical stress state and treated as such in a fatigue damage model. The fatigue damage mechanisms in CFRP under thermal loading have been studied in detail. For this purpose, an extensive experimental program was conducted to systematically explore the damage mechanisms from the single fiber level to the multilayer laminate structure. The transfer of the knowledge gained from the experiments into mathematical models enabled the phenomena to be reproduced in simulations and partially explained.

Publications

• Interfacial shear strength of a glass fiber/epoxy bonding in composites modified with carbon nanotubes. Composites Science and Technology, 70(9), 1346-1352.
  Godara, A.; Gorbatikh, L.; Kalinka, G.; Warrier, A.; Rochez, O.; Mezzo, L.; Luizi, F.; van Vuure, A.W.; Lomov, S.V. & Verpoest, I.
  
• Fatigue damage model for fibre-reinforced polymers at different temperatures considering stress ratio effects. Journal of Composite Materials, 52(29), 4023-4050.
  Lüders, Caroline; Krause, Daniel & Kreikemeier, Janko
  
• Adaptive cycle jump and limits of degradation in micromechanical fatigue simulations of fibre-reinforced plastics. International Journal of Damage Mechanics, 28(10), 1523-1555.
  Lüders, Caroline; Sinapius, Michael & Krause, Daniel
  
• Fatigue of fibre-reinforced plastics due to cryogenic thermal cycling. Journal of Composite Materials, 53(20), 2849-2861.
  Lüders, Caroline & Sinapius, Michael
  
• Experimental and numerical multiscale approach to thermally cycled FRP. Composite Structures, 244, 112303.
  Lüders, Caroline; Kalinka, Gerhard; Li, Wei; Sinapius, Michael & Wille, Tobias
  
• Nonlinear-Elastic Orthotropic Material Modeling of an Epoxy-Based Polymer for Predicting the Material Behavior of Transversely Loaded Fiber-Reinforced Composites. Journal of Composites Science, 4(2), 46.
  Lüders, Caroline
  
• “Mehrskalige Betrachtung des Ermüdungsverhaltens thermisch zyklierter Faserkunststoffverbunde”. Dissertation. Technische Universität Carolo-Wilhelmina zu Braunschweig, 2020
  C. Lüders