How to design and execute multiaxial fatigue tests for wind turbine blades without sensitive design data?

This article proposes a methodology to design and execute multiaxial fatigue tests for wind turbine blades without the need to use sensitive design data, such as blade cross-sectional geometry. An approach based on bending moments is used, which matches the actual strain behavior of the material in all regions of beam-like structures under cyclic loading. To facilitate the implementation of the proposed methodology, a numerical validation of the equality between damage indices obtained from bending moments and strains is carried out using a commercial blade of fully known design. Then, an experimental demonstration of how to obtain the proposed bending-moment-based damage indices during real fatigue tests is performed using a large commercial blade with unknown design. It is expected that with the application of the proposed methodology, better fatigue tests can be carried out for these structures than those designed following current standards.