Ultrasonic inspection of composite hydrogen reservoirs using frequency diversity techniques

The use of the signal processing techniques based on the principle of quasi -frequency diversity can be a suitable solution for the ultrasonic inspecti on of liquid hydrogen tanks manufactured out of composite materials. Nevert heless, the algorithms developed up to now suffer from limitations that res trict their large-scale use. The split-spectrum processing requires prelimi nary adjustments that are not always accessible to the user, while the cut- spectrum processing is not sensitive enough to eliminate the noise. We have thus developed an interesting alternative to these two filters. Based on t he use of progressive low-pass filters, this algorithm, called low-spectrum processing, takes into account the physical characteristics of the ultraso nic wave propagation in a composite material. Its use in the inspection of tanks made in composites showed better performances. (C) 2001 Elsevier Scie nce B.V. All rights reserved.