DEVELOPMENT OF A DUAL-AXIS PHASE-LOCKED RESONANT EXCITATION TEST METHOD FOR FATIGUE TESTING OF WIND TURBINE BLADES

Collaborative efforts between Embry-Riddle Aeronautical University (ERAU) and the National Renewable Energy Laboratories (NREL) have resulted in an innovative dual-axis phase-locked resonant excitation (PhLEX) test method for fatigue testing of wind turbine blades. The Dual-axis phase-locked test method has shown to provide more realistic load application as compared to wind loading experienced through field operation conditions. The current concepts involved exciting the blade at its fundamental edgewise natural frequency while applying a force in the flap direction at that same frequency. This advanced test method incorporates existing commercially available test hardware, known as the Universal Resonant Excitation (UREX), combined with an additional hydraulically actuated member to dynamically force the blade using adaptive algorithms and advanced control strategies in order to provide cycle-to-cycle phase control and decreased testing time. In short, this paper will outline the development of a finite element model for predicting performance and evaluation of the results.