TOFD Inspection with Phased Arrays

摘要

In the last decades two major technologies changed the face of ultrasonic NDT viz., time of flight diffraction (TOFD) and phased array ultrasonic testing (PAUT). When used in conjunction, these two techniques allow for higher probability of detection (POD), normally requiring a great amount of time and/or experienced UT inspectors. To do TOFD however (even TOFD by itself),it is necessary to have different sets of probes with different probe separations when one wishes to inspect very thick materials.With the advent of more sensitive transducer arrays and faster electronics, we can now envisage, using multi-element probes, to perform multiple TOFD inspections (the different apertures, offsets and refracted angles all being changed electronically) in one run and with a minimum number of props. These different TOFD scans may also be merged a posteriori so that a simple global picture finally emerges from the acquired data.In this paper we will present some results achieved with this method as well as both theoretical and practical aspects of the problem.