Billson, Duncan R. (1994) Advanced non-contacting ultrasonic techniques for non-destructive testing. PhD thesis, University of Warwick.

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Abstract

This thesis describes research towards the development of ultrasonic methods to test samples that are difficult to test using conventional techniques, with particular emphasis being given to non-contacting methods. The samples investigated in detail were adhesively bonded structures and zircalloy (a zirconium-niobium alloy).

The adhesively bonded structures were investigated ultrasonically using an ultrasonic resonance technique (referred to as ultrasonic spectroscopy) to analyse suitable ultrasonic waveforms. This thesis starts by explaining a new approach to ultrasonic spectroscopy, and then describes a number of transduction techniques (both contacting and non-contacting) that were devised to obtain waveforms suitable for spectroscopic analysis. These including conventional piezoelectric transducers, laser generation of ultrasound, EMAT reception of ultrasound, and a novel couplant-free transducer. Tests were undertaken on a variety of samples under a number of different conditions, with the experimental results comparing well with those predicted by theory.
Zircalloy was investigated next in an effort to evaluate non-destructively the concentration of hydride in the alloy. This was performed using velocity-temperature measurements (at temperatures up to 500°C) for both shear and longitudinal waves, and by dilatometry (thermal expansion) measurements. Both sets of tests successfully determined the hydride concentrations of test samples.

A separate chapter is devoted to the description of some of the novel transducers developed during the course of this research, including a couplant-free transducer, and several transducers for airborne ultrasound. These transducers were found to operate well, the couplant-free transducer being particularly successful (subsequently finding a number of industrial applications). The final experimental chapter describes the building of both a photoelastic, and a schlieren rig that were used to visualise ultrasound, with the intention of giving an insight into some of the ultrasonic phenomena that were associated with the rest of the work. The results obtained were invaluable in analysing the results from previous chapters.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QC Physics Q Science > QD Chemistry T Technology > TA Engineering (General). Civil engineering (General)
Library of Congress Subject Headings (LCSH):	Nondestructive testing, Ultrasonic testing, Spectrum analysis, Zirconium compounds -- Nondestructive testing
Official Date:	June 1994
Dates:	Date Event June 1994 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Hutchins, David C.
Format of File:	pdf
Extent:	xv, 146 leaves : illustrations
Language:	eng

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