Health monitoring of wind turbine blades in operation using three-dimensional digital image correlation

Wind turbine blades are subjected to fluctuating loads during operation, which makes them vulnerable to reduced performance and mechanical failures. In addition, the maintenance of blades is time-consuming and expensive. In this paper, a novel and economic optical technique based on three-dimensional digital image correlation (3D-DIC) is described for monitoring the health of wind turbine blades. A fault detection method is proposed based on the relative deformation of the turbine blades during operation. To validate the approach, a 5 kw wind turbine with 4 m diameter was evaluated using 3D-DIC. The rotor blades were prepared with a random black-and-white pattern of dots and two digital cameras were located in front of the wind turbine to document the rotor blade deformation. The full-field dynamic parameters of displacement and strain were obtained and a diagnosis of the blade health was conducted in both the time and frequency domains. Results showed that 3D-DIC can serve as an effective non-contact method for monitoring the health of wind turbine blades during operation.