Ultrasonic Time of Flight Diffraction (TOFD) Image Processing Principal investigators:- Dr Shaun Lawson and Gary Bonser

Time-of-flight diffraction (TOFD) ultrasonic testing is potentially one of the fastest methods of Non-destructive testing (NDT) since a weld can be characterised to a certain degree with one single traverse along its length with two probes. The method is relatively new and was first developed at AEA Harwell in the late 1970's by Maurice Silk and others. Data is stored in a digital format with a single vertical 'scan' line characterising the structure of the weld at any one position. In this way, an image of the complete weld is built up, showing component and, more importantly, any defect information.

The MSRR Group have recently developed image processing software (running under a 32-bit Windows environment on a PC) which can automatically interpret TOFD scans which have been acquired using either an AEA Technology Microplus or Zipscan system. The software, which uses neural network methods to perform the initial segmentation of a scan, can be used to automatically locate any defects in an on-line inspection situation. The package may also be used to cue a manual inspector to any welding problems as they manifest themselves in the on-line NDT data, or to preprocess automatically batch scanned data. The software was recently demonstrated at the Final Ultrasonic Trials of the BRITE-EURAM II project BRE2-0319 ("NDT Methods for Flaw Detection during Welding").

Further information :-

Shaun Lawson

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