COMPUTERIZED, ROBOTIC ULTRASONIC C-SCAN SYSTEM FOR INSPECTION OF AEROSPACE STRUCTURES

At the present time, bonded composite and metal aerospace structures require extensive nondestructive evaluation; flaws that can occur during extremely complex processing and fabrication are often subtle and difficult to detect. This paper will present recent advances in nondestructive evaluation of large-scale composite components using a fully computerized, robotic, ultrasonic C-scan system. This state-of-the-art ultrasonic system incorporates two synchronized Unimation Puma robots, a Hewlett Packard computer with graphics, a MatEval Micropulse ultrasonic unit and a 12-foot turntable. The system can record and analyze ultrasonic signals on parts with surface area greater than 100 m2. Using newly designed low-noise ultrasonic liquid jet nozzles and accurate defect standards based on Grafoil inserts, the system's ability to detect and identify critical defects in composites is greatly enhanced. Test frequency range is from 1/2 to 10 MHz for both through-transmission and pulse-echo modes of operation. The ultrasonic amplitude recording spans a dynamic range of 80 dB and permits tracking of signals in up to eight independent time gates. The analysis of measurements is software programmable; results are presented to the operator via colour graphic CRT or colour plotter.