Structural optimisation of composite wind turbine blade structures with variations of internal geometry configuration

Structural optimisation techniques are frequently used as part of the design process for composite wind turbine blades. Most commonly this is achieved by modifying material placement within a standard structural design; less attention has been paid to the possibility of varying internal geometry to create novel structural configurations. In this work, a series of wind turbine blade designs with differing structural configurations have been created and compared to investigate the effect of allowing various aspects of the internal structural geometry to be varied. The geometry of the structural spar is thoroughly investigated by modifying the width of the spar caps, and the number and location of shear webs including the spanwise starting and ending locations. The location and extent of a trailing edge reinforcement are also considered, along with the material thickness distribution of the spar and trailing edge reinforcement. A series of five parametric 2D finite element models with geometry and materials placement variables were created and incorporated into a genetic optimisation algorithm. This method allows the optimisation process sufficient freedom to generate designs without being constrained by preconceived ideas of how the internal geometry should be configured. The optimum designs had mass reduced relative to the baseline by 3.5-7.4%. Structural analysis of the optimum designs revealed that the active constraint varied greatly between the different designs, and it is therefore recommended that a wider range of loading cases and constraints needs to be accounted for in optimisations that allow the structural geometry to vary compared to those that use a standard geometry.