Development of Fatigue Test System for Small Composite Wind Turbine Blades

Abstract

The research was to develop a small blade fatigue test system which met the criterion of the IEC (TR 61400-23) for the small composite wind turbine blades (SCWTBs). The fatigue test machine consisted of the servo motor, linear guide, transmission, controlling system and clamping apparatuses. These components were used to balance the weights loaded on the blades. Weights were added to change the different mass at each saddle for the loading tests. Amplitude of fatigue can be manipulated by rotating the eccentric holes of the flywheel. The kinetic power of the SCWTBs was translated from the circular motion to linear motion. The fatigue test system was able to test 1m-3m SCWTBs with single or multiple samples tested simultaneously. Because vibration frequency of the fatigue test system was limited to 3-6 Hz, this research also tested the repaired samples after breaking them intentionally for the tests. Finally, the paper drew the linear formulation of the Goodman diagram. The experimentally determined S-N curve for R = –1 was used to define the intercepts of the constant life curves of the vertical axis of the SCWTBs.