<p> Acoustic parameters (velocity and attenuation-coecient) are known to be sensitive to the Degree of Sensitization (DoS) in aluminum alloys. The attenuation coecient has been shown to be more sensitive to DoS than transverse and longitudinal wave velocities. There is a need to investigate ways of improving the precision (reducing the error bars) in the attenuation coecient. In this thesis, two methods for generating source signals, and two techniques for analyzing the received signals, both using the Pulse{Echo ultrasonic technique, were investigated. The two techniques of analysis (time- and frequency-domain correlation) were compared with the scope of observing the variation in the precision of the attenuation coecient, with the frequency-domain correlation technique found to be slightly more precise. In addition, a comparison was made between the frequency-domain correlation technique developed in this thesis and the technique previously used by the group to obtain the acoustic parameters. The frequency-domain correlation technique was found to be comparable, in terms of errors, with the current technique. Most importantly, it was also found to be much faster (480 times faster than the current technique), less tedious, since it is automated. A conclusion that the frequency-domain correlation technique would be suitable for analyzing very large data sets (e.g in material health monitoring), with less eort, can be drawn. Further, because of the ease-of-use, large sets of data can be analyzed quickly to allow for proper statistics, making frequency dependent measurements of acoustic parameters of interest an easier task.</p><p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:13420604 |
| Date | 05 April 2019 |
| Creators | Osunkwo, Sonny O. |
| Publisher | University of Louisiana at Lafayette |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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