Investigation of Air Coupled Ultrasonic C-Scan Imaging By Signal Analysis
Traditional ultrasonic techniques always need the aid of couplant (water or gel) for transmitting of the ultrasound. In the nondestructive inspection of some materials and structures, water-coupled ultrasonic inspection is often not desirable due to contamination and property alteration concerns. Some examples include composite and foam structures in space applications and honeycomb sandwiches cannot tolerate water ingression. Therefore, air-coupled ultrasonic inspection is an attractive alternative for such applications. This paper describes the effects of different variables such as gain, scanning speed, averaging signals and scanning axis in air coupled C-scan imaging by signal analysis. Based on the results obtained from the study, the ultrasonic C-scanning process carried out at higher gain, higher averaging signals and lower speed can give better C-scan images which figure out the structure of tested materials more clearly.
Keywords- Air coupled ultrasonic, composites, c-scan imaging flaw detection.