Numerical Evaluation of Design Strategies for a Composite Wind Turbine Blade: Using Metallic Foams and Optimising Topology

This study investigates and assesses two different strategies for the design of wind turbine blades, consisting of two components: the external shell made of carbon fibre-reinforced epoxy and the internal beam. The first strategy is based on designing the blade through the selection of the beam material. Aluminium and aluminium foam with different porosity levels are considered for the beam material. The moduli of elasticity of the foams were calculated using the Mori-Tanaka approach and ranged from 70 GPa for solid aluminium to 23.3 GPa for foams with 50% porosity. Then, using these results, the finite element simulations under various loading conditions are performed. It is observed that increasing the foam porosity from 0% to 50% results in a 50% reduction in beam weight, with only a 35% decrease in the specific stiffness. The second strategy involves a topology optimisation of the internal beam to determine the most structurally efficient geometry for the blade through finite element analyses. Aluminium is considered the beam material for topology optimisation studies. The topology optimisation leads to a 53% reduction in the beam mass compared to the initial design, while maintaining performance metrics within acceptable limits. The mechanical behaviour of blades designed with these two strategies is investigated in eight different positions during a complete revolution in steady-state. The results are compared to each other, as well as a blade with a balsa beam as a benchmark. By providing a comprehensive assessment and comparison, this study provides a better understanding of how the chosen design method affects blade performance and demonstrates the balance between weight reduction and structural efficiency.