Kinematic analysis and dynamic modeling of a novel fatigue loading mechanism considering wind turbine blade effects

Abstract

With the continuous increase in the size and flexibility of wind turbine blades, conventional fatigue testing methods are facing severe challenges. Although some studies have proposed using a planar 5R parallel mechanism as an alternative loading system, most of the existing work has focused on the mechanism itself without adequately considering the coupling interaction between the blade and the mechanism. To address this gap, the blade is simplified in this study as a two-degree-of-freedom spring-mass-damper system, and the kinematic equations and workspace of the mechanism are derived. On this basis, a coupled blade–mechanism dynamic model is developed using the Lagrangian formulation. Finally, simulations are conducted under flapwise, edgewise, and biaxial loading conditions. The results reveal that, when blade effects are included, the torque and power demands of the driving joints increase significantly. The novelty of this work lies in incorporating blade characteristics into the dynamic analysis of the 5R parallel mechanism, thereby uncovering the critical influence of blade effects on mechanism performance. This research provides a theoretical foundation for advancing wind turbine blade fatigue testing equipment.