Probabilistic micromechanical analysis of composite material stiffness properties for a wind turbine blade

This work presents a coupled approach for stiffness property prediction of composite materials used in wind turbine blades using an advanced micromechanics and reliability-based methodologies. This approach demonstrates how to map the uncertainties in the fiber and matrix properties onto the equivalent stiffness properties of composite laminates. Square and hexagonal unit cells were employed for the estimation of the composite equivalent properties. The finite element formulation of the unit cells were performed in the ANSYS Multiphysics. The results from numerical experimentation conform well with the available test data and to the results from the Modified Rule of Mixture (MROM). A probabilistic analysis using Monte Carlo Simulation with Latin Hypercube Sampling was used to assess the uncertainties in the equivalent properties according to the variability in the basic properties of the constituents. Furthermore, a sensitivity analysis based on the Spearman Rank Order correlation coefficients was carried out to highlight the influence of important properties of the constituents. As an illustration, the above approach is applied to analyze a 5 MW wind turbine blade section under static loading. Results demonstrate the possibility of the coupled approach at macro level (structure) from micro level (unit cell) with the aim to design robust structures.