Experimental Research on Ultrasonic 2-D SAFT of Concrete Elements

Abstract

Synthetic aperture focusing technique (SAFT) has a promising approach in ultrasonic nondestructive testing (NDT) methods and subsequently focuses on the data measured on an aperture to every point of the reconstructed imaging area through the superposition of the time records. To validate the potential of this method, an experimental system is established to perform cross-surface scan of the test specimen, and a SAFT processing program is used to give a 2-D display of the inner structure of the specimen based on the measured backscattered ultrasonic signals. Two different concrete specimens were cast with embedded objects. Design of the inspection pulse, for example, the pulse shape and central frequency is discussed. According to SAFT imaging algorithm, the images of these concrete structures are pictured. Compared to the original B-scan method, SAFT gives a better imaging quality.