ASSESSING THE FATIGUE RESPONSE OF GLASS FIBER REINFORCED SUSTAINABLE POLYMER MATRIX COMPOSITES

Rapid climate change has necessitated the need for finding clean and green sources of energy. The offshore wind and tidal energy sector has found increasing relevance in this regard. Polymer composites can be functionally viable materials while offering distinct advantages such as high specific mechanical properties and better corrosion resistance over traditional materials such as steel, which are widely employed at present in the construction of offshore energy structures. However, inadequate material characterization data under various loading conditions, especially fatigue is hindering their large-scale utilization for offshore structural applications. The EU-funded FIBREGY project is aimed at addressing this material characterization inadequacy to increase the use of composites in offshore structures while reducing their environmental impact. In this paper, the fatigue behavior of unidirectional glass fiber composites under tension-tension loading is presented. A bio-based thermoset epoxy resin and an infusible thermoplastic resin were the matrix materials for the composites. The composites were tested in a direction transverse to the fiber axis. In addition to the conventional S-N curve method to determine fatigue life, the thermography technique was employed to assess the fatigue behavior of the composites. The behavior of the composites with thermoset and thermoplastic matrix materials were compared and the results are included. The fatigue limit of composites with the thermoplastic matrix was over 20 % lower as compared to that of composites with thermoset matrix. Further, the failure mechanisms and fracture characteristics of the composites were studied by examining the fracture surfaces of failed specimens using Scanning Electron Microscopy technique. The observations are discussed in the context of the fatigue test results.