Application of PVDF Film Sensor to Detect Early Damage in Wind Turbine Blade Components

Abstract

Monitoring technique for detection of early damage in the wind turbine blade has been investigated using PVDF film sensor and strain gages. The trailing edge component with shear web was prepared by sectioning the full-scale blade with a box spa. Several PVDF film sensors with dimension of 10x10x0.054 mm3 and strain gages were installed on shear web and skin of the component and the behaviour of these sensors were examined under opening and closing loads. From the test, optimal location for detecting the occurrence of damage with static loading was investigated and sensitivity of the PVDF sensors location to the damage was examined. With increasing the applied load, several pop-ins happened up to final failure. The outputs of the PVDF film sensors under quasi-static loads showed the relatively insignificant magnitude and peaks corresponding to pop-ins. So, it is found that PVDF film sensors mounted on the trailing edge component give an early response remarkably to the damage occurrence irrespective to the closing and opening loads. Therefore, it can be said the PVDF film sensors may be significantly useful in detecting the instance of damage occurrence in the trailing edge component. Further, it can be recommended that the relatively good location of the PVDF sensor to detect the damage in the trailing edge component be the locations free to the geometrical constraint, like the center of spar web and the blade skin remote from the joint between the spa cap and the shear web.