2014 Volume 27 Issue 2 Pages 42-48
This paper describes fuzzy average difference imaging for ultrasonic nondestructive testing. In our experiment, we employ a piece of wind turbine blade as a specimen. The specimen has holes on back side as artificial damages. We acquire ultrasonic waveforms from scanning lines on surface of the specimen using an ultrasonic single probe. We make cross-section images of the specimen by correcting the each scanning line wave data. We set scanning lines so that specimen constructions under the lines are same each other. Therefore the images show same construction of inside of the specimen, we can enhance the damage echoes by using average difference imaging. To extract the damage echoes from the images, we applied damage extraction method aided by fuzzy logic and average difference imaging. As the results, we found the line image with all damage portions, and we estimated depth of damage surface with high accuracy. Therefore fuzzy average difference imaging showed effectiveness for extracting difference potions on similar images.