AN ULTRASONIC ARRAY-BASED SYSTEM FOR REAL-TIME INSPECTION OF CARBON-EPOXY COMPOSITE PLATES

A real-time ultrasonic imager operating at a frequency of 3.5 MHz to t est composites in immersion has been developed. It is based on linear array transducers and provides either B-scan or transmission images of composite plates of a few centimetres thickness. The electronic scann ing has a pitch of 1.25 mm and an amplitude of 80 mm, and the electron ic focusing as well as the acoustic lens on the arrays are set to work at a depth of 40 mm in water. Tests made on composite and plastic pla tes of 5 to 17 mm thickness show that the system allows the detection of different types of defects and that the interpretation of the ultra sonic signals can be performed on line.