Acoustic emission NDE of a wind turbine blade during full-scale testing

The use of renewable energy sources has rapidly increased in the European Community during recent years. Particularly in Greece, the high wind energy: potential favours the installation and use of Wind Turbines (W/T). As a result, it has become necessary to find an effective NDT method for the structural integrity assessment of W/T blades, which are the most vulnerable W/T parts. The present paper is a brief summary of the results of non-destructive evaluation of a new; 12 m wind turbine blade made of FRP, using the acoustic emission technique, during controlled, static and fatigue stimulation. The test was carried out at the Centre for Renewable Energy Sources, in Athens and data analysis was performed by Envirocoustics ABEE. The AE technique revealed that the maximum chord area was a critical area of the blade, before any damage had become apparent, from the first, already static loaning. Fatigue test results verified the existence of flaws ill the critical area Pointed out by the first static loading, Follow-up visual inspection revealed a 20 cm long crack at the trailing edge of the blade at the maximum chord area, which first became visible after several thousands of fatigue cycles had occurred between the two tests.