Flaw detector incorporating DGS

摘要

Apparatus (10) for performing ultrasonic flaw testing of a material (M) or assembly. A pulser (28) generates an electrical pulse having defined characteristics. A transducer (12) converts the signal to an ultrasonic pulse, propagates the pulse through the material or assembly, receives an echo the characteristics of which include reflections off flaws or discontinuities in the material or assembly, and converts the echo into an electrical reply signal. The transducer is selectable from among a number of transducers. A processor (32) processes the reply signal to produce a visual display representing the amplitude of the reply signal for a range of propagation times (distances) into the material. A visual display (16) displays the processed electrical signal. A correlation module (42) generates a gate signal which is visually displayed (at 38) with the processed electrical signal. The gate signal corresponds to a maximum amplitude value which represents the maximum flaw size allowable for the test. If the displayed amplitude of the processed electrical signal exceeds the maximum amplitude value, the material or assembly fails the test. The correlation module emulates a series of DGS curves for the transducer used during the test. This is done to take into account test parameters related to the transducer and the material, so after an initial calibration of the apparatus is performed using a selected transducer and a reference reflector, valid test results are obtained with the transducer regardless of the distance of the reflector.