Fracture Monitoring of Composite Wind Turbine Blade Using High-Speed Bragg Grating Sensor System
This paper introduces a FBG (fiber Bragg grating) based AE (acoustic emission) sensing system for use in health monitoring of composite wind turbine blades. In this study, a multiplexing high speed FBG sensor system was developed with a spectrometer-type demodulator based on a linear photo detector. Pencil break test was performed using an FBG sensor and the results were compared with the results of piezo-based AE sensor. For the performance test of fracture sensing in composite materials, a down-scaled wind turbine blade was fabricated and drop impact tests were performed. Arrayed 4 FBG sensors were installed in the skin of wind turbine blade and impacts of 15 J energy were applied by a drop weight. The frequency characteristics of impact induced AE signals were examined with short-time Fourier transform focused on the leading waves. Finally, the onset of fractures in composite structure was successfully assessed using arrayed FBG sensors.
Yongping Zhang, Linhua Zhou and Elwin Mao
H. J. Bang and S. H. Kim, "Fracture Monitoring of Composite Wind Turbine Blade Using High-Speed Bragg Grating Sensor System", Applied Mechanics and Materials, Vol. 109, pp. 79-83, 2012