A Micromechanical Modeling Approach for the Estimation of the Weathering-Induced Degradation of Wind Turbine Blades

Abstract Glass fiber reinforced polymers (GFRPs) are widely used as composite material for a variety of applications such as wind turbine blades (WTBs). During their operating time, these GFRP structures are exposed to natural weathering conditions, such as low and elevated temperatures, ultraviolet radiation, and moisture. These weathering phenomena influence the material’s mechanical properties due to material aging and the degradation of the composite’s mechanical properties. For a reliable lifetime assessment and the design of a repurposed application of WTBs, the quantification of GFRP’s degradation is required. For this reason, the aim of the current study is to numerically estimate the combined effects of weathering on the mechanical properties of GFRP. Therefore, the effective elastic properties of a unidirectional GFRP composite were determined considering representative volume elements. The required numerical modeling was performed using finite element analysis. The mechanical properties of glass fibers, epoxy resin and their relationship with individual natural aging phenomena were used based on the existing literature values. As a result of the micromechanical modeling, the change of temperature and moisture absorption have the highest effect on the elastic properties on the epoxy resin and thus also on the GFRP composite. The used numerical approach enables a preliminary estimation of environmental-based degradation phenomena of GFRP which can be used at an early stage of developments of composite structures, the reuse of composites or for planning experimental studies considering degradation of these composite materials.