The Development of a Phase Locked Wind Turbine Blade Finite Element Model to Predict Loads and Deflections during Fatigue Testing

Full scale blade testing provides blade manufacturers with quantitative data in order to assess blade design, manufacturing and durability. Structural testing is a requirement in order to design reliable blades, and to develop a further understanding of the dynamics involved in a modern turbine blade. Blade tests can be conducted in either a single axis or dual axis configurations. Historically, fatigue testing has been performed by utilizing forced displacement systems. These systems do not allow for the load phase angle to be controlled, and the maximum load application in the edge and flap directions are allowed to vary. The PhLEX (Phase Locked Excitation System) under development utilizes a resonant excitation system in order to reduce hydraulic requirements, decrease test duration and improve distributed load matching. Control of the phase angle will allow for more accurate testing of the blade. This thesis paper will detail the method and theory used to develop a model of a phase locked resonant test system for structural testing of wind turbine blades