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Dissertations / Theses on the topic 'Ultrasonic testing'

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Published: 4 June 2021
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1

Whitcomb, Richard W. "Quantitative ultrasonic evaluation of concrete." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/19004.

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2

McLaren, S. "High-resolution ultrasonic non-destructive testing." Thesis, City University London, 1987. http://openaccess.city.ac.uk/8335/.

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The use of ultra-short pulse wideband ultrasonic transducers in Non-Destructive-Testing (NDT) has been investigated both theoretically and experimentally. It is demonstrated that the resolution of pulse-echo NDT is affected by diffraction effects which also complicate the interpretation of echo signals. These diffraction effects are interpreted in terms of the plane- and edge-wave model of *transducer fields. Improverents can be obtained by the use of non-uniformly excited transducers of two basic types: the first, the plane-wave-only (PWO) source; is more strongly excited at its centre than towards the rim, where the excitation is gradually reduced to zero in order to remove the edge wave. The second type, an edge-wave-only (EWO) source, is more strongly excited at its rim than in the centre, thereby effectively removing the plane wave. Computer modelling of pressure waveforms in the field of PWO and EWO sources has been carried out using an extension to the impulse response method. Experimental point-pressure waveform measurements in the field of a prototype EWO transducer, made using a miniature ultrasonic probei are in reasonable agreement with the calculated results. Detailed calculations are made of the transmit-receive mode (pulse-echo) responses arising from solid targets of various size in a flu- id medium interrogated by uniformly and non-uniformly excited sources. The theoretically predicted results are in good agreement with experimentally measured results obtained using a conventional transducer and an equivalent prototype EWO transducer. The effects of target size, field position and material on both the amplitude and shape of the echo responses are investigated. The structure of the responses is explained in terms of the plane and edge waves radiated by the source. Implications for the use of techniques to both size (Distance, Gain, Size curves) and characterise (ultrasonic spectroscopy) defects are examined. The applications of new, nonuniformly excited transducers in high-resolution NDT and ultrasonic imaging are evaluated.
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3

Wright, William Matthew David. "Air-coupled ultrasonic testing of materials." Thesis, University of Warwick, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319811.

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4

Engström, Torsten. "Ultrasonic Testing of INCONEL Alloy 600." Thesis, KTH, Fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193126.

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5

Mamilla, Amala Kishore. "Ultrasonic Couplants at Elevated Temperatures." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/MamillaAK2004.pdf.

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6

Tsang, Wai-ming Peter. "Computer aided ultrasonic flaw detection and characterization /." [Hong Kong : University of Hong Kong], 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12344928.

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7

Isleyici, Umut. "Effect Of Surface Roughness On Ultrasonic Testing." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606937/index.pdf.

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This study investigates the effect of front surface roughness on ultrasonic echo amplitude. Experiments were carried out on specimens whose front surfaces are machined by milling machine. Machining parameters were changed in milling process in order to obtain desired roughness values and milling head was tilted to a very small angle to obtain periodic rough surfaces. Experiments were performed with these specimens having roughness value of 0.5, 4.5, 11, 26.5 µ
m. Ra. The back surface roughness of all specimens was kept constant at 1.5 µ
m Ra by grinding operation. 1.5, 2, 3, 4 mm. holes were drilled at constant depth and to same side of each specimen to represent reference discontinuities. Ultrasonic tests, using pulse echo technique were carried out to monitor echo amplitudes corresponding to different roughness values. The tests were also repeated by using different ultrasonic probes having different frequencies. For additional comparison, different couplants were used through the tests. The results showed that there was a significant increase in the reduction of the sound pressure level with the increase in the surface roughness. Although there was no uncertainty observed about not being able to detect discontinuity because of roughness but correct couplant and frequency selection has a positive effect on correctly sizing the discontinuity and at attenuation measurements. The results obtained with this work can be used as a guide for testing rough surfaces, predicting the effect on ultrasonic examination before testing and discontinuity detecting capability under rough surface conditions.
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8

Roberts, D. R. "Ultrasonic spot weld testing with automatic classification." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638690.

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Spot welds are used to join sheet steel in automobile bodies. To ensure vehicle integrity, these welds, must be tested. Ideally, non-destructive testing would be employed. However, spot weld quality in the automotive industry is currently assessed using destructive methods. Spot welds can be tested non-destructively with ultrasound. Operators place a single crystal ultrasonic probe on a weld and interpret the returning signal to estimate the quality of the weld. However, this ultrasonic method has not been widely accepted in the past, possibly due to difficulties in manually quantifying the information contained in the signals. In an attempt to make ultrasonic testing viable for automotive use, a system has been created which automatically interprets the ultrasonic signals and classifies welds as good or bad. There are two main aspects to the systems. Firstly, echoes occurring within the signal are identified by an algorithm. This was developed after discovering the sequence in which the critical intermediate echoes occur. The second aspect of the system is classification of the spot weld based upon certain features of the identified echoes. The strength of the intermediate echoes was found to be primary source of information on weld size. Extensive experimental studies were designed and conducted to identify other potential information sources. Notably, the attenuation rate of the back-wall echoes in the signal was investigated. Most published papers in the field report that signal attenuation may be used to estimate weld size. It has been generally believed that the grain structure of the welded steel significantly increases ultrasound scattering, leading to higher attenuation is not caused by weld grain structure. The evidence gathered strongly favours weld surface irregularities as the primary cause of ultrasound attenuation in spot welds.
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9

Lin, Lin. "On the Generation and Detection of Ultrasonic Plate Waves in Microporous Polymeric Material." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/LinL2003.pdf.

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10

曾偉明 and Wai-ming Peter Tsang. "Computer aided ultrasonic flaw detection and characterization." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31231007.

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11

Costley, R. Daniel Jr. "Laser generation of Rayleigh and Lamb waves for ultrasonic nondestructive testing." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17627.

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12

Tant, Katherine M. M. "Time-frequency domain modelling for ultrasonic nondestructive testing." Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24448.

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This thesis endeavours to develop and implement new and improved methods for the characterisation of defects embedded in steel welds through the analysis of data collected by ultrasonic phased array inspections. A factor common to the existing imaging techniques used for flaw characterisation is the subjective thresholding required to estimate the size of the flaw. The work contained in this thesis uses the mathematics of inverse problems and scattering theory to extract information about such defects and puts forward an objective approach which employs a mathematical model. A relationship between the pulse-echo response curve of a scattering matrix and the size and orientation of a flaw is derived analytically via the Born approximation and results in a completely objective approach to crack sizing. Further expansion of these relationships allows for expressions to be formulated concerning the minimum resolvable crack length and the effects of array pitch and flaw depth on the accuracy of the algorithm. The methodology is then extended and tested on experimental data collected from welded austenitic steel plates containing a lack of fusion crack. In the latter part of this thesis, work focusses on the exploration of the fractional Fourier transform and coded excitations. The fractional Fourier transform allows for retention of both time and frequency domain information simultaneously and permits the in homogeneous wave equation (with a forcing function prescribed as a linear chirp modulated by a Gaussian envelope) to be solved in time-frequency space. This in turn facilitates a comparison between a gated continuous wave excitation and a Gaussian modulated linear chirp. It is observed that the Gaussian modulated linear chirp results in a marked increase in the scattering amplitude.
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13

Alleyne, David N. "Nondestructive testing of plates using ultrasonic Lamb waves." Online version, 1991. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.263143.

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14

Li, Bo. "Detection of particles and estimation of size distribution in process fluids /." Online version of thesis, 1992. http://hdl.handle.net/1850/11258.

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15

Deroo, Frederik. "Damage detection in concrete using diffuse ultrasound measurements and an effective medium theory for wave propagation in multi-phase materials." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31801.

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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Laurence J. Jacobs; Committee Member: Jianmin Qu; Committee Member: Jin-Yeon Kim. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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16

Blum, Frank. "A focused, two dimensional, air-coupled ultrasonic array for non-contact generation." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180005/unrestricted/blum%5Ffrank%5F200312%5Fms.pdf.

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17

廖威賢 and Wai-yin Liu. "Ultrasonic reflection tomography over circular aperture." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1992. http://hub.hku.hk/bib/B31210910.

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18

Abulail, Seren I. "Ultrasonic characterization of ASTM A307 bolts." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Thesis/Fall2008/s_abulail_112108.pdf.

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Thesis (M.S. in civil engineering)--Washington State University, December 2008.
Title from PDF title page (viewed on Apr. 17, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 40).
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19

Retaureau, Ghislain J. "Detection of Surface Corrosion by Ultrasonic Backscattering." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11498.

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Corrosion often occurs in the inner aluminum lining of the HB-53 helicopter external fuel tank, resulting in fuel leaks. This project centers on developing an in-situ ultrasonic inspection technique to detect corroded areas inside the fuel tank. Due to the complexity of the composite structure of the tank, the ultrasonic inspection is carried out from inside the tank using a monostatic backscattering technique. The backscattered field contains information related to the insonified surface properties (surface roughness scales). Numerical predictions are implemented with a simplified model of backscattered intensity (Ogilvy, 1991). Experimental results are obtained on artificially corroded plates, and on the actual fuel tank of the HB-53 helicopter. Signal processing techniques (Envelope Correlation and Inverse Technique) are used to detect corroded surfaces with data obtained with a focused 10 MHz pulsed transducer.
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20

Tavrou, Chrysostomos Kyriacou, and stavrou@swin edu au. "Evaluation of adhesively bonded steel sheets using ultrasonic techniques." Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20060306.085412.

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Adhesives have presently reached a stage where they have become part of everyday life both in a professional sense as well as for household applications. They offer advantages that in many respects surpass other joining processes such as bonding of large areas, joining a wide range and dissimilar materials; and without the need for special tooling or operator training, that is often required by many other joining processes. They are of course not a panacea to all fastening applications, but they can easily be described as the most versatile and most widely used joining method at present. Engineering applications have also benefited from the advantages offered by adhesives, but they are not as liberally used due to the severe consequences that may result from bond failure. Although adhesives can demonstrate their ability to fulfil the joining strength requirements under laboratory conditions, their application in industry proved to be not as reliable as expected. A number of parameters that can easily be controlled under laboratory conditions such as temperature, humidity, surface preparation and uniform adhesive application are not as easily observed in industry. Quality assurance during manufacturing can achieve excellent results; however even in these cases the probability of having adhesive bond defects is still present. Therefore, there is a need for post process inspection of adhesive bonds where risk levels require higher reliability than what is offered though process quality control. Adhesive bond inspection is a well researched area with respectable outcomes. Non destructive inspection techniques such as x-ray, thermal, and ultrasonic are well utilised in the inspection of adhesive bonds. However, despite all the effort in this area for more than forty years, there is still no singular technique that can achieve the confidence level required in some engineering applications. Therefore, the need for continuing research in the area of non-destructive evaluation of adhesive bonds is as necessary today as it�s ever been. The research presented in this thesis, continues in the same endeavour as many other researchers; that of achieving the ultimate technique in adhesive bond inspection, capable of reaching the confidence level required for all engineering applications. The research in the thesis commenced with coverage of adhesives used for engineering applications and a study of the adhesion science that was considered necessary to enable an informed approach to the problem. Adhesive bond failure is also analysed through a literature survey as well as experimental tests on standard specimens. At the completion of the literature survey and preliminary tests, a decision was taken to follow the ultrasonic path of non-destructive testing of adhesive bonds. The reasons for this, are clearly outlined in the main body of this thesis but in summary, the literature has shown that ultrasonic evaluation is the most widely used technique by industry. Therefore, improvements on data analysis using existing techniques that exploit ultrasonic inspection have the potential to reach the widest spectrum of industrial applications. Ultrasonic inspection equipment was sourced that was capable of achieving experimental results to the accuracy level required in this research. A precision test rig was designed and constructed that was subsequently calibrated using computer based statistical techniques to ensure the validity of all results. Other ancillary equipment, such as a portable tensile testing device were also designed and constructed during the research as it became necessary. Research concentrated on techniques found to be inadequately researched in this domain. The first technique evaluated was to measure bond quality through the stress distribution in adherent and adhesive. Computer based Finite Element Analysis showed that the ability to detect variation in stress distribution at the adhesion interface is capable of revealing the local bond strength. Having found that there is no technique available at present that can measure the stress distribution at the interface, a different direction was taken that showed potential in achieving excellent quantitative results in the analysis of ultrasonic signals from adhesive bonds. This technique was rigorously evaluated and the results are systematically reported in this work.
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21

Wilkinson, Gordon Peter. "An integrated wide bandwidth ultrasonic signal acquisition instrument." Thesis, Keele University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385557.

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A wideband digital signal acquisition instrument intended primarily for ultrasonic experimentation has been designed and built. It comprises an integrated array of modules which combine to provide: a pulser for transducer excitation, wideband amplification (>80 MHz bandwidth), high speed sampling (>160 MHz), on-board memory (4K x 16 bits capacity), control hardware and real-time coherent averaging. The integration of the modules offers significant benefits over systems consisting of a number of separate items of equipment. The major benefit is a reduction in acquisition time which is accomplished as follows. The time relationship between the sampling clock and the input signal is controlled to minimise the signal repetitions required for interleaving. This is achieved by triggering the input signal using a pulser board locked to the sample clock. In addition, signal averaging is implemented in hardware using two memory modules and an adder module. Since the time relationship between the sampling clock and the input signal is controlled it cannot be tested using a sinewave because it is not possible to produce a sinewave which is correlated with the sampling clock. Instead, a rectangular pulse, triggered by the instrument, is applied to a single-pole low pass filter to provide the test signal. The time constant and start time is ascertained and used to reproduce the single-pole response. The reproduced response is then compared to the sampled signal to produce an error plot from which the system's linearity and effective bits can be deduced. As the system was designed for fast acquisition, and hence has a short aperture time, it is highly applicable to dynamic processes. The dynamic process application chosen was the measurement of absorption and velocity on rapidly flocculating and sedimenting colloids.
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22

Chan, Tony T. T. "Ultrasonic method of non-destructive test in metals effects of grain size on ultrasound wave at various frequencies /." access abstract and table of contents access full-text, 2006. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21456276a.pdf.

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Thesis (M.Sc.)--City University of Hong Kong, 2006.
"Master of Science in Materials Engineering & Nanotechnology dissertation." Title from title screen (viewed on Nov. 21, 2006) Includes bibliographical references.
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23

Drinkwater, Bruce Walton. "The use of dry coupling in ultrasonic nondestructive testing." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296521.

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24

Billson, Duncan Robert. "Advanced non-contacting ultrasonic techniques for non-destructive testing." Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/107577/.

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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.
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25

Lam, Hung-yiu. "Pulse compression filter design for ultrasonic non-destructive testing /." Hong Kong : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18933580.

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26

Liu, Wai-yin. "Ultrasonic reflection tomography over circular aperture /." [Hong Kong] : University of Hong Kong, 1992. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13440019.

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27

Bergh, Charles Ferguson. "Development of an interferometric system for process monitoring." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19281.

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28

Lau, Connie K. Y. "Non-destructive evaluation with ultrasonic pulse velocity (UPV) in concrete structure." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21174441a.pdf.

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Thesis (M.Sc.)--City University of Hong Kong, 2005.
At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 1, 2006) Includes bibliographical references.
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29

Mong, Seng Ming. "Non-destructive evaluation with ultrasonic pulse velocity (UPV) in concrete structure." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175032a.pdf.

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Thesis (M.Sc.)--City University of Hong Kong, 2005.
At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
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30

Punurai, Wonsiri. "Cement-based materials' characterization using ultrasonic attenuation." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04042006-171125/.

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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006.
Dr. Jennifer Michaels, Committee Member ; Dr. Jacek Jarzynski, Committee Member ; Dr. Jianmin Qu, Committee Member ; Dr. Laurence J. Jacobs, Committee Chair ; Dr. Kimberly E. Kurtis, Committee Co-Chair.
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31

Barkefors, Annea. "3D Synthetic Aperture Technique for Ultrasonic Imaging." Thesis, Uppsala University, Signals and Systems Group, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-121022.

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The group for non-destructive testing at Uppsala University has recently implemented the phase shift migration method, which is a method to focus images acquired unfocused using ultrasound. However, their work has been limited to 2D data, while for many applications the gathered data is 3D. This project has extended the old implementation to 3D data. The new implementation has been done in two different ways, giving one algorithm that works fast but needs much RAM, and one algorithm that takes long time but works on smaller computers, not demanding as much memory. The fast algorithm works faster than the time it takes to acquire the raw data, which makes real-time use realistic. To test the performance of the two algorithms with respect to image improvement, both against each other and against the previous 2D implementation, a number of experiments were carried out, which showed that, apart from processing time, the two new algorithms were equal in performance. The experiments also showed that the obtained resolution in both x- and y-directions matched the theoretical discussion.

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32

Beadle, Brad Michael. "Fiber optic sensor for ultrasound." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17869.

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33

Beadle, Brad Michael. "Fiber optic sensor for ultrasound." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19173.

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34

Cornwell, Matthew Allen. "Determination of the bending stiffness of copy paper and its dependence on temperature and moisture using laser ultrasonic lamb waves." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19636.

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35

林鴻耀 and Hung-yiu Lam. "Pulse compression filter design for ultrasonic non-destructivetesting." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B3121423X.

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36

Zeitvogel, Daniel Tobias. "Characterization of damage due to stress corrosion cracking in carbon steel using nonlinear surface acoustic waves." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45809.

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Cold rolled carbon steel 1018C is widely used in pressurized fuel pipelines. For those structures, stress corrosion cracking (SCC) can pose a significant problem because cracks initiate late in the lifetime and often unexpectedly, but grow fast once they get started. To ensure a safe operation, it is crucial that any damage can be detected before the structural stability is reduced by large cracks. In the early stages of SCC, microstructural changes occur which increase the acoustic nonlinearity of the material. Therefore, an initially monochromatic Rayleigh wave is distorted and measurable higher harmonics are generated. Different levels of stress corrosion cracking is induced in five specimens. For each specimen, nonlinear ultrasonic measurements are performed before and after inducing the damage. For the measurements, oil coupled wedge transducers are used to generate and detect tone burst Rayleigh wave signals. The amplitudes of the received fundamental and second harmonic waves are measured at varying propagation distances to obtain a measure for the acoustic nonlinearity of the material. The results show a damage-dependent increase in nonlinearity for early stages of damage, indicating the suitability for this nonlinear ultrasonic method to detect stress corrosion cracking before structural failure.
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37

Spratt, William. "Design and Testing of an Ultrasonic Torsional Wave Sensing Platform." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/SprattW2009.pdf.

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38

Thornicroft, Keith. "Ultrasonic guided wave testing of pipelines using a broadband excitation." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/14001.

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Guided Wave Testing (GWT) is a relatively new development in non-destructive testing. Conventional Ultrasonic Testing (UT) methods are operated at high frequencies (MHz) and are capable of detecting very small (down to micrometre-scale) flaws within a range of millimetres from a transducer. GWT, however, is carried out at lower frequencies (kHz) and is capable of highlighting the position of volumetric structural detail and discontinuities, such as gross corrosion at a minimum of 9% of the cross-sectional area, tens of metres from a test location. Conventional ultrasonic testing relies on the transmission of bulk waves whereas GWT employs so-called ultrasonic guided waves (UGW). To simplify UGW inspections, several tests are conducted sequentially at a range of different excitation frequencies. The frequency bandwidth of each of these tests needs to be controlled to avoid complexities caused by the frequency dependent nature of the propagation of guided waves. This gives rise to the current GWT inspection procedure, where a number of different narrowband tests are conducted at several distinct frequencies. It is also found that different test circumstances (such as pipe coating or defect type) are inspected more easily with certain excitation frequencies than with others - and the optimum frequency can not always be predicted ahead of time. Thus, where time allows it is often beneficial to carry out a frequency sweep, whereby a large range of excitation frequencies are incrementally generated - for example, from 20 to 80kHz in 1kHz steps. This research proposes a novel approach to the existing pipeline inspection procedure by utilising the information contained within a broadband response. The overarching proposition given by this research is that the current collection procedure be entirely rewritten. This thesis will present ideas related to every area of the inspection procedure beginning with the tuning of excitation signals and concluding with recommendations on how tooling and excitation configuration can be modified to further optimise the technique for broadband excitation.
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39

Kwasniak, Peter James. "Construction and Testing of an Ultrasonic Transducer for Biofilm Removal." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302099986.

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40

Seifried, Robert. "Propagation of guided waves in adhesive bonded components." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19494.

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41

Sun, Miao. "Optimal Recovery of Elastic Properties for Anisotropic Materials through Ultrasonic Measurements." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/SunM2002.pdf.

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42

Littles, Jerrol W. Jr. "Ultrasonic characterization of Fiber Reinforced Polymeric (FRP) composites." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19160.

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43

Graham, George M. "On-line laser ultrasonic sensing for control of robotic welding quality." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/16949.

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44

Hopko, Sandra N. "Laser ultrasonic probe for industrial or high temperature applications." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/16433.

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45

Yung, Kan-Chuen Winco. "Control and qualification of titanium welds." Thesis, Brunel University, 1997. http://bura.brunel.ac.uk/handle/2438/5356.

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The study was aimed at controlling the weld geometry of thin-plate titanium and one of its alloys (Ti-6Al-4V) by ultrasonic means and qualiFying the metals in the as-welded condition in terms of their grain sizes and mechanical properties. The alignment and symmetry of the weld pools were successfully tested by using ultrasonic shear waves. The grain sizes at the weld fusion zone were found to be related to their ultrasonic attenuation by a mathematical relationship. The temperature effect in locating weld pool radii in titanium was found at temperatures up to 600 °C. The ultrasonic velocity decreased as the temperature increased and the square of temperature affected the rate of change of the ultrasonic velocity. After compensation for the temperature effect, the maximum location error of the weld pool radius was 17 % which was comparable to previous measurement using different techniques.A positive relationship was seen between weld geometry (penetration depth and weld width) and heat input. A welding spectrum for titanium and its alloys of different thicknesses was obtained. Back shielding gas was beneficial in obtaining good welds. Both heat input rate and cooling rate were found to affect the grain size of the weld, with the cooling rate being the dominant factor. The grain size exhibited a Hall-Petch effect on mechanical properties, such as the tensile properties and fracture toughness of the weld. The phase transformation positively contributed to better mechanical properties in most cases, whilst the presence of interstitials worsened tensile properties. A system was developed in this study to utilise the above information and data for possible real-time and closed-loop control of the TIG welding process to give a desirable weld. Specifically, a process control data base was built up using software and a knowledge-based system for acceptable welding parameters, which were determined by acceptable penetration depth, grain size and mechanical properties. An algorithm was successfully written which relates the ultrasonic signal to the penetration depth of the weld. A hardware control circuit was built which took in the ultrasonic signal and converted it to a driving signal to change the welding speed and thereby change cooling rate.
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46

Olsen, Karl R. "Ultrasonic detection of simulated corrosion in 1 inch diameter steel tieback rods." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Dissertations/Summer2009/k_olsen_052609.pdf.

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Thesis (Ph. D.)--Washington State University, August 2009.
Title from PDF title page (viewed on Aug. 4, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 110-111).
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47

Rainisch, Uri. "Detection of Ultrasonic Lamb Waves in Paper Using an Optical MEMS Microphone." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4779.

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Laser ultrasonics has been used to measure the bending stiffness of paper products by measuring the dispersion of ultrasonic plate waves. In laser ultrasonics, ultrasound can be generated by absorption of pulsed laser spot while detection can be carried out by Laser Doppler Interferometry. The research presented in this paper describes a new method to detect ultrasonic plate waves using a recently developed acoustic transducer, more specifically an optical Micro ElectroMechanical System (MEMS) microphone with broadband capability. The MEMS device operates as a non-contact proximity probe placed less than ¼ a millimeter away from the plate. The signals are detected with a capacitive micromachined ultrasonic transducer (cMUT) in which the back electrode of the capacitive transducer on a transparent substrate is shaped as an optical diffraction grating. The displacement of the transducer membrane is determined using an optical interferometer. By applying voltage to deflect the membrane electrostatically, the detection sensitivity is kept at an optimum level. The main purpose of the research presented herein was to test this MEMSs ability to detect ultrasonic waves propagating through paper, to increase the signal-to-noise ratio (SNR), and to calibrate the device in order to quantify the limitations on sensitivity in the context of the detection of ultrasound in paper. Similar tests were conducted for comparison with a modified Mach-Zehnder Interferometer, a more traditional method used for laser ultrasonic detection, and its results are presented in this paper.
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48

Campbell, M. A. "An evaluation of monolithic phased arrays for Non destructive testing." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381502.

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49

Nayfeh, Taysir H. "A direct on-line ultrasonic sensing method to determine tool and process conditions during turning operations." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-165721/.

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50

Dressler, Marc. "Theoretical and experimental modeling of ultrasonic waves in multi-layered media." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/21535.

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