This study aims to verify the reliability of non-destructive tests by applying them to wind turbine composite blades.
For achieving this purpose, three kinds of artificial specimens were produced by inserting the forms of blade faults which are most frequent, in different positions and then, as non-destructive tests, infrared thermography, ultrasonic testing, phased array ultrasonic testing, radiographic testing and digital radiography were applied to compare and evaluate the possibility of fault detection.
For infrared thermography, outer heat sources of the specimens were examined using an active method and the heat sources were measured using an infrared camera. The faults of the positions with temperature changes were detected by analyzing the temperature changes of the measured images.
For ultrasonic testing, straight-beam ultrasonic testing was conducted as a direct-contact method using the pulse-echo method. Based on the signals detected, it was possible to detect the faults by analyzing the echo depending on the positions of the faults.
For phased array ultrasonic testing with the same basic principle as ultrasonic testing, the depth values and the widths of the faults were observed by applying A scan and B scan, at the same time.
For radiographic testing, industrial X-Ray images were acquired by setting the exposure time in consideration of the distance with the specimens and the thicknesses of the specimens, and the faults were detected using film''s density differences.
Lastly, for digital radiography, the faults of the specimens were detected using fine ray sources and digital detector.
In this research, all the tests were possible to detect the faults, but some of them were impossible to detect the faults below 3 mm. In conclusion, this means that for improving the reliability of blade tests, there is a need to conduct complementary tests rather than depending on one method.