An efficient procedure for the calculation of the stress distribution in a wind turbine blade under aerodynamic loads

In the current state-of-the-art, computational fluid dynamics (CFD) analysis and Blade Element Momentum (BEM) based models are used to analyse and design a wind turbine blade. CFD code simulations are accurate but very time consuming. Instead, BEM based codes are quick but they are not able to calculate the local stress/strain that appear at different positions on the blade. This paper presents the development of an automated procedure for aero-structural analysis that calculates the global and local stress/strain results on a wind turbine blade for different wind conditions. The pressure distribution along the blade due to the wind loading is calculated based on a two-and-a-half-dimensional aero-elastic analysis. With this methodology, the wind loads depend on blade deformations, that is, wind loads are coupled with blade deformations. As a practical example, the whole procedure is applied to the 5 MW UpWind wind turbine blade. The methodology is validated against FAST and Bladed codes giving good agreement. This methodology saves time and provides the necessary data in order to perform subsequent studies such as blade structural behaviour analysis.