Development and Validation of a Full Matrix Capture Solution

For the last 15 years, phased array has completely changed the face of ultrasonic non-destructive testing. This now-mature and widely adopted technology allows highly efficient inspections to be carried on critical components in aerospace, oil & gas, heavy industry and power generation plants. The Full Matrix Capture (FMC) technique is an upcoming and promising application of the phased array technology. It consists of capturing and storing all possible time-domain signals (A-Scans) from every transmitter-receiver pair of elements in the array. After recording, all raw information is available to generate the data resulting for any given beam (aperture, refracted/skew angles, focusing position), through off-line processing. This paper will address the challenges faced in order to achieve an efficient FMC data collection and will show the data processing capabilities that the technique has to offer. Results of a complete validation program will also be presented. Moreover, various aspects of the hardware and software specification will be addressed, highlighting the potential benefit of enhanced performance on the FMC implementation. INTRODUCTION For long mostly used for medical and laboratory applications, the phased array (PA) UT technology has now been embraced by the non-destructive testing industry. Since the early 2000’s, its adoption has been a game-changer for ultrasonic inspections of critical components in aerospace, oil & gas, heavy industry and power generation plants. A new advanced method for applying PA UT is also currently making the transition from laboratories to industrial applications: the Full Matrix Capture (FMC) technique. This paper will give a detailed explanation of the principles supporting FMC. It will illustrate the benefits of the FMC technique over standard PA processing, and address the challenges faced in order to achieve an efficient FMC data collection. Results of a complete validation program, including thorough comparisons with standard PA processing, will also be presented. Moreover, various aspects of the hardware and software specifications will be addressed, highlighting the potential benefit of enhanced performance on the FMC implementation. STANDARD PHASED ARRAY PROCESS VS FULL MATRIX CAPTURE In order to introduce the principles of the FMC technique, a short reminder of the standard PA principles is presented. The PA technology uses multiple independent UT transmitting-receiving channels. During the emission process, standard PA systems apply time delays to the individual elements of a PA probe in order to generate a physical ultrasonic beam with specific acoustic characteristics through constructive interference of the individual wavefronts. In reception, these standard systems also apply time delays to the signals received by the individual elements in order to put them in phase for the hardware summation process. The summed and digitized A-Scan signal is then transferred to the computer for display and recording (see Figure 1).