Damage assessment of wind turbine blade under static loading test using acoustic emission

Abstract

Acoustic emission is known as a powerful nondestructive tool to detect any further growth of preexisting cracks or to characterize failure mechanisms. Recently, this kind of technique, which is an in situ monitoring of integrity of materials or structures, becomes increasingly popular for monitoring the conditions of large structures such as a wind turbine blade. Therefore, it is required to find a symptom of damage progress before catastrophic failure through a continuous monitoring. In this study, acoustic emission technology was applied to assess the damage in the wind turbine blade during step-by-step static load test. In this static loading test, we have used a full-scale blade of 100 kW in capacity, and an attempt was made to apply a new source location method using a new algorithm with energy contour mapping concept. We also measured the deflection of blade tip by linear variable differential transformer (LVDT) and the strain of inner shear web in order to analyze the correlation between stress condition and damage identification. The results show that the acoustic emission activities give a good agreement with the stress distribution and damage location in the blade, especially in bonding edges around 1000–1500 mm far from the root. Finally, the applicability of new source location method was confirmed by comparison of the result of source location and experimental damage location.