Basis for remote monitoring of the condition of wind turbine blades

Specific technical requirements were defined for the sensors capability to detect the most important damage types in wind turbine blades. Different sensor types were selected for use in laboratory experiments and full-scale tests of a wind turbine blade developing damage: 1) detection of stress wave emission by acoustic emission, 2) measurement of modal shape changes by accelerometers and 3) measurement of crack opening of adhesive joint by a fibre optics micro-bend displacement transducer that was developed in the project. All types of sensor approaches were found to work satisfactory. The techniques were found to complement each other nicely. NDT methods (ultrasound scanning and X-ray inspection) were found to be useful for verifcation of hidden damage