NDE Techniques of Fiber Characterization in Spar Caps of Wind Turbine Blades using Ultrasonic Waves

Recently, ultrasonic waves (UT) have attracted attention as a tool for nondestructive evaluation (NDE) in various fields, including agriculture, medical engineering, and airport security. In this study, carbon fiber reinforced plastic (CFRP) materials are inspected during the fabrication process. Ultrasonic techniques are commonly used to evaluate composites in spar caps of wind turbine blades. Therefore, the fiber orientation and defects of composites are investigated using one-sided ultrasonic measurements to evaluate the soundness of CFRP composites in spar caps of wind turbine blades. Compared with the ultrasonic pulse-echo method, the ultrasonic pitch-catch method is effective in the receiving ultrasonic signals on the composites. Ultrasonic signals must be controlled at arbitrary depths of CFRP composite laminates; this is called a “sampling volume.” Therefore, ultrasonic signals can be obtained at arbitrary depths of composites in any sampling volume.