Dissertations / Theses on the topic 'Ultrasonic inspection'
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1
Hesse, Daniel. "Rail inspection using ultrasonic surface waves." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444161.
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Egerton, Jack Samuel. "Ultrasonic inspection of highly attenuating media." Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/62627.
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The aim of the project was to improve the ultrasonic array inspection of high-density polyethylene (HDPE) heat-fused pipe joints of cooling water pipework that is installed in EDF Energy's nuclear power stations. Whereas ultrasound array inspection is now established for safety-critical metal components, HDPE poses a hugely challenging problem, that the ultrasound waves are heavily attenuated by the material. This impacts multiple aspects of the inspection and of the modelling that is needed to design and qualify inspection. The thesis reports a range of research that was needed to overcome this challenge. The work of the thesis has: - obtained accurate acoustic properties of HDPE that are necessary for improved simulated or real ultrasonic array imaging of HDPE pipe joints - developed a simulation technique for representing ultrasound in such inspections that has both high accuracy and efficiency - extended analytical analysis of ultrasound scattering from cylindrical voids from elastic media to general, attenuative media - used the Huygens-Fresnel principle to represent ultrasound scattering from volumetric and planar voids, to image sub-wavelength features of these defects in an ideal circular array setup, and to image angled ultrasonic array nondestructive evaluation (NDE) of potential defects occurring in HDPE pipe joints - devised an automated and antidispersive system for reducing coherent and incoherent noise in waveforms with an isolated wave reflection signal - produced an imaging and analysis method for ultrasonic array NDE that can represent defects in a refractive, reflective, and scattering environment in attenuating media, which is applied to data from the above developed simulation technique - applied much of the above imaging and analysis method to defects machined into HDPE pipe material, with an experimental ultrasonic array controller, yet with an array of limited suitability - specified parameters for ultrasonic arrays and a water-filled wedge, which are optimum for HDPE pipe joint inspection, and have been designed and built by Imasonic SAS, France, for research use at Imperial College London.
3
Van, Pamel Anton. "Ultrasonic inspection of highly scattering materials." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/29423.
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Ultrasonic Non-Destructive Evaluation (NDE) relies on the scattering of waves from discontinuities, such as fractures or voids, to probe media otherwise invisible to the naked eye. Whilst this has been industrially exploited for several decades within acoustically transparent materials, many materials maintain a microstructure that causes scattering of the propagating waves. This undermines the aforementioned premise as it becomes exceedingly difficult to discern the features of interest from the scattering inherent to microstructural features, thereby limiting the range of materials which can be reliably inspected, non-destructively. Experimental investigations confirm the challenges and significant shortcomings for the inspection of future industrial components where such microstructures are desirable for their mechanical properties. It is demonstrated that the rapid increases in scattering with the insonifying frequency severely limit the achievable sensitivity of conventional ultrasound techniques. A review of the latest advances in ultrasound technology, including signal processing and imaging algorithms, explore the opportunities to exceed current limitations and advance the capability of ultrasonic NDE. Establishing these advances, and those of future approaches, requires a rigorous definition of performance. In contrast to commonly adopted strategies, a novel strategy which considers the probabilities of detection and false alarms is proposed as a valuable benchmark that can be used to make objective comparisons in terms of performance between competing algorithms. Future progress will also rely on a better scientific understanding of scattering, which can be provided by powerful modelling tools. Here, Finite Element modelling is established to be very useful; it captures the complex scattering physics and allows an investigative flexibility which can provide extremely useful insights. Whereas previous studies have often been restricted to weak scattering assumptions, the present FE modelling capability now enables the study of more complex, highly scattering environments. This is demonstrated by investigating ultrasonic arrays, where through optimising their engineering, especially in terms of their configuration, significant performance enhancements are shown to be possible. These important scientific tools have enabled the assessment of the latest imaging algorithms, the optimisation of inspection configurations, and increased our understanding of scattering phenomena. Their use in the future enables wide possibilities towards further pursuing the ultrasonic inspection of highly scattering materials.
4
Gomez, Gutierrez Francisco Jose. "Ultrasonic sensing methods for sewer pipe inspection." Thesis, King's College London (University of London), 2006. https://kclpure.kcl.ac.uk/portal/en/theses/ultrasonic-sensing-methods-for-sewer-pipe-inspection(bbd5712a-4856-47ed-af76-4ea21eda052f).html.
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Valdes, Abel. "Development of laser ultrasonic and interferometric inspection system for high-volume on-line inspection of microelectronic devices." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29685.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Ume, I. Charles; Committee Member: Kalaitzidou, Kyriaki; Committee Member: Mayor, J. Rhett. Part of the SMARTech Electronic Thesis and Dissertation Collection.
6
Moya, Jorge A. Salcedo. "Ultrasonic inspection of underwater piping system with thick coatings." Connect to resource, 1994. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=osu1260632892.
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Milne, Katherine Anne. "Studies into the Vibro-Enhancement of Penetrant Inspection and the Ultrasonic Inspection of Diffusion Bonds." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516757.
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Palanisamy, Suresh, and n/a. "Ultrasonic inspection of gas porosity defects in aluminium die castings." Swinburne University of Technology. Industrial Research Institute Swinburne, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20060828.103450.
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This thesis documents a PhD research program undertaken at Swinburne
University of Technology between the years 2000 and 2004. The research was
funded by the Cooperative Research Centre for Cast Metals Manufacturing and was
undertaken in collaboration with Nissan Casting Plant Australia Pty Ltd and the Ford
Motor Company Australia Limited. This thesis reports on the investigation of the
possibility of using an ultrasonic sensing-based, non-destructive testing system to
detect gas porosity defects in aluminium die casting parts with rough surfaces. The
initial intention was to develop a procedure to obtain ultrasonic signals with the
maximum possible amplitude from defects within the rough surface areas of the
castings. A further intention was to identify defects with the application of a suitable
signal processing technique to the raw ultrasonic signal. The literature review has
indicated that ultrasonic techniques have the potential to be used to detect subsurface
defects in castings. The possibility of classifying very weak ultrasonic signals
obtained from rough surface sections of castings through a neural network approach
was also mentioned in the literature. An extensive search of the literature has
indicated that ultrasonic sensing techniques have not been successfully used to detect
sub-surface defects in aluminium die castings with rough surfaces.
Ultrasonic inspection of castings is difficult due to the influence of
microstructural variations, surface roughness and the complex shape of castings. The
design of the experimental set-up used is also critical in developing a proper
inspection procedure. The experimental set-up of an A-scan ultrasonic inspection rig
used in the research is described in this thesis. Calibration of the apparatus used in
the inspection rig was carried out to ensure the reliability and repeatability of the
results. This thesis describes the procedure used to determine a suitable frequency
range for the inspection of CA313 aluminium alloy castings and detecting porosity
defects while accommodating material variations within the part. The results
obtained from ultrasonic immersion testing indicated that focused probes operating at
frequencies between 5 MHz and 10 MHz are best suited for the inspection of
castings with surface roughness Ra values varying between 50 [micro milli] and 100 [micro milli]. For
the purpose of validating the proposed inspection methodology, gas porosity defects
were simulated through side-drilled holes in the in-gate section of selected sample
castings. Castings with actual porosity defects were also used in this research.
One of the conclusions of this research was that it was extremely difficult to
detect defects in castings with surface roughness above 125 [micro milli]. Once the ultrasonic
signal data was obtained from the sample aluminium die castings with different
surface roughness values ranging from 5 [micro milli] to 150 [micro milli] signal analysis was carried
out. Signal feature extraction was achieved using Fast Fourier Transforms (FFT),
Principal Component Analysis (PCA) and Wavelet Transforms (WT) prior to passing
the ultrasonic signals into a neural network for defect classification. MATLAB tools
were used for neural network and signal pre-processing analysis. The results
indicated that poor classification (less than 75%) was achieved with the WT, PCA
and combination of FFT/PCA and WT/PCA pre-processing techniques for rough
surface signals. However, the classification of the signals pre-processed with the
combination of WT/FFT, FFT/WT and FFT/WT/PCA classifiers provided much
better classification of more than 90% for smooth surface signals and 78% to 84%
for rough surface signals. The results obtained from ultrasonic testing of castings
with both real and simulated defects were validated with X-ray analysis of the
sample castings. The results obtained from this research encourage deeper
investigation of the detection and characterisation of sub-surface defects in castings
at the as-cast stage. Implications for the industrial application of these findings are
discussed and directions for further research presented in this thesis.
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Palanisamy, Suresh. "Ultrasonic inspection of gas porosity defects in aluminium die castings." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20060828.103450.
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Thesis (PhD) - Swinburne University of Technology, Industrial Research Institute Swinburne - 2006.A thesis submitted to the Industrial Research Institute Swinburne, Swinburne University of Technology in fulfilment of the requirements to the degree of Doctor of Philosophy, 2006. Typescript. Includes bibliographical references (p. 199-211).
10
Long, Robert. "Improvement of ultrasonic apparatus for the routine inspection of concrete." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343846.
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Ageeva, Victoria. "Endoscopic cheap optical transducers (CHOTs) for on-wing ultrasonic inspection." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/38682/.
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The instrumentation and the developments presented in this thesis aim to address the challenges associated with in-service non-destructive testing of aeroengine components, imposed by severe restrictions on component accessibility. In-service non-destructive testing (NDT) is essential to ensure early detection of service-induced damage and prevent catastrophic failures of such safety-critical aeroengine components as turbine/compressor blades and disks, increasing the safety of operations and dramatically reducing the cost of engine changes. The main concern during their inspection is detection of fatigue cracking, typically initiated on the surface of the part. The application of inspection techniques used during overhaul to on-wing testing is restricted both by the complex, spatially-confined access to the components and the inaccessibility of the high-stress concentration surfaces in the full engine assembly. Two routinely-used techniques providing a solution to these challenges are the use of endoscopes for access and surface acoustic waves to inspect parts of the assembly. CHOTs are optically-activated ultrasonic transducers located on the surface of a sample, that use laser illumination to remotely generate and detect ultrasound, providing a non-contact wireless alternative to conventional piezoelectric transducers (PZTs). The benefits of optical activation are paired with fibre-optic light delivery in an endoscopic pulser -- a simple portable ultrasonic inspection system with flexible instrumentation, beneficial for testing hard-to-reach components in locations with limited access or hazardous environments. This thesis presents the instrumentation of the endoscopic pulser and the development of the self-adhesive portable CHOTs (SA CHOTs) to complement its potential field application by enabling transducer delivery to components in-service and application to large and curved parts, previously limited by laboratory-based direct on-sample CHOT fabrication. The developed transducers overcome frequent barriers for industrial adaptation of fully-optical inspection systems presented by the sample surface conditions such as reflectivity and roughness. The NDT capabilities of the CHOTs endoscopic pulser are demonstrated by performing detection of machined slots on controlled aluminium samples and representative industrial parts using 4--5 MHz surface acoustic waves. System capabilities for active structural health monitoring (SHM) as well as inspection of samples in motion are demonstrated. Although in its present configuration the size of the endoscope exceeds practical access requirements, the potential of the system for further development and miniaturisation is discussed.
12
Cleary, Daniel. "CURVED AND TIGHT RADIUS INSPECTION OF CARBON FIBER REINFORCED POLYMERS WITH ACOUSTOGRAPHY." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2390.
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In this research, Acoustography Nondestructive Evaluation method was investigated for inspecting “tight radii” in carbon fiber reinforced polymer (CFRP) components. Ultrasonic inspection of tight radii is challenging because of refraction and/or mode conversion of ultrasound waves at the entry and exiting surfaces of the tight radii. Snell’s law was used to first study the refraction and/or mode conversion behavior of the ultrasound beam at the entry and exiting surfaces of a CFRP panel; to help establish the angular range over which ultrasound is transmitted through CFRP material. Snell’s law data was then used as a guide for setting up the Acoustography system and part orientation to optimize inspection of several real-world CFRP components containing tight radii. CFRP tight-radii specimens were prepared by strategically placing markers around the tight radius of each specimen to ensure full coverage of the tight radius region. Acoustography inspection was first performed with a straight beam to establish limitation of the straight beam in detecting markers in the tight-radii region, as predicted by Snell’s law. Acoustography inspection was then performed using a multi-angle beam (+/- 12.5o) to improve detection of markers in the tight-radii region. Results confirmed that straight beam (flat transducer) could not penetrate the sample at the start of the tight radius because of refraction or mode conversion effects. However, the use of multi-angle beam (multi-angle transducer) greatly improved the penetration through the tight radius because some of beam angles were within the ultrasound transmission range for the tight radii. Experiments were also performed by changing orientation of the CFRP sample under the multi-angle or straight beam. Sample orientation was changed at five-degree increments so that optimum conditions for the tight-radii inspection could be determined. This research provides a basis on which further improvements can be made to advance the Acoustography NDE method for the inspection of tight radii in CFRP components.
13
Tyas, Nicholas Harvey. "Grain refinement of austenitic stainless steel welds to facilitate ultrasonic inspection." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620965.
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Garner, Simon. "Laser ultrasonic testing for on-line inspection of laser metal deposition." Thesis, Swansea University, 2015. https://cronfa.swan.ac.uk/Record/cronfa42997.
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Foister, Steven A. M. "The interaction of ultrasound with the material structure of titanium alloys." Thesis, University of Surrey, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301330.
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Baltazar-Lopez, Martin Eduardo. "Applications of TAP-NDE technique to non-contact ultrasonic inspection in tubulars." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/1614.
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The possibility and feasibility of experimental detection of localized defects in tubes using laser-induced ultrasonic wave approach through Thermo Acousto Photonic Non Destructive Evaluation (TAP-NDE) and Signal processing through wavelet transform is examined in this research. Guided waves in cylindrical surfaces provide solutions for detection of different defects in the material. Several experiments were conducted to this respect. Wave propagation in both axial and circumferential directions was studied. The dispersive wave propagation of ultrasonic waves in hollow cylinders has been investigated experimentally, primarily for use in non-contact and nondestructive inspections of pipes and tubes. The laser ultrasonic waves propagated in cylindrical waveguides are particularly attractive because of their unique characteristics in the applications of nondestructive evaluation (NDE). Contrary to studies making use of only axially symmetric guided waves in hollow cylinders, here are analyzed also nonaxisymmetric waves. The analysis of data is made by using the Gabor wavelet transform. The capability of modeling the guided wave dispersion in hollow cylinders is used in developing guided wave experimental techniques for flaw detection. Good agreement was obtained when comparing the dispersion spectra between theory and experimentation. Measurement of group velocities of guided waves, which are obtained directly from the wavelet transform coefficients, can be used to determine allocation and sizing of flaws.
17
Telford, D. W. "Ultrasonic inspection techniques for testing sodium/water heat exchangers using Lamb waves." Thesis, University of the West of Scotland, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372392.
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Gebru, Hezekiah. "Assessment of ultrasonic inspection techniques and models for nuclear power plant components." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/30920.
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Reliable detection and sizing of small and complex flaws is paramount in safety critical Nuclear Steam Raising Plant (NSRP) components and the pressure vessels of Pressurised Water Reactors (PWR). Also accurate modelling approaches are fundamental to understand the propagation and the scattering of ultrasonic waves from defects to aid interpretation of their ultrasonic responses. The objectives of this work are twofold: firstly, to assess the reliability of existing ultrasonic inspection techniques in detection and sizing of small and complex defects in ferritic steel. Secondly, to validate the finite element (FE) and CIVA simulation methods in modelling propagation of ultrasonic waves and scattering from geometrically simple defects. Experimental results have shown that the Time-of-Flight Diffraction (TOFD) technique is effective in locating and sizing linear cracks in welded ferritic components, though not arrays of small pores, and under-clad carbon cracks. It has also been shown that the pulse-echo phased array technique is efficient for defect detection. The TFM post-processed FMC data produces images of defects with a superior resolution than the pulse-echo phased array technique. Finite element simulations of waves in isotropic and transversely isotropic steels have predicted wave speeds agreeing well with theory. Similarly, the bulk elastic velocities in isotropic steel using the commercial simulation software CIVA have been found to be in close agreement with theory, however, significant discrepancies were found in the shear velocities in the transversely isotropic steel. The validations of the FE and CIVA modelling techniques for scattering from a small circular hole and a semi-infinite crack were performed. The FE predictions of the scattered and diffracted fields were in good agreement with analytical solutions. The corresponding CIVA predictions also agreed well with theory, though not close to the specular direction and at large receiving angles. Finally, FE and CIVA simulations of the TOFD technique were carried out on an ultrasonically smooth crack and a pore. The results were presented as B-scan images; the simulated B-scan images were in harmony with the experimental studies.
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Advani, Siddharth Kishin Rose Joseph L. Zhang Qiming. "An ultrasonic guided wave inspection system for hard to access civil structures." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4435/index.html.
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Stonawski, Ondrej. "NON-DESTRUCTIVE EVALUATION OF CARBON/CARBON BRAKES USING AIR-COUPLED ULTRASONIC INSPECTION SYSTEMS." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1674101471&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (M.S.)--Southern Illinois University Carbondale, 2008."Department of Mechanical Engineering and Energy Processes." Keywords: Air-coupled ultrasonic, Carbon/carbon brakes, Nondestructive evaluation. Includes bibliographical references (p. 114-115). Also available online.
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Haig, Alexander George. "The use of macro fiber composite transducers for ultrasonic guided wave based inspection." Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/12840.
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Sound can propagate for long distances with a low loss of intensity in objects whose geometry acts as a guide for the sound waves; a phenomenon that can be utilised for long range testing of structures. The guided sound waves can be used to conduct materials evaluation or to detect flaws, which can be done for a relatively large region of coverage from a relatively small region of access. In particular this technology can be used to inspect or monitor large engineering structures whose structural integrity is critical for safety and the environment, such as wind turbine towers, ship hulls, and pipelines. The use of guided waves for structural inspection is complicated by the existence of many wave modes. In this thesis, the Macro Fiber Composite (MFC) is characterised for its frequency, wavelength, wave mode and direction dependent sensitivity. These devices are flexible, light and thin, and, here have been shown to have wave mode sensitivity characteristics that are favourable for some applications. The MFC is a piezoelectric actuator that can be used to excite and sense in-plane vibrations at a structures surface. The surface area of an MFC is significantly large with respect to typical wavelengths used in ultrasonic guided wave applications, which combined with their in-plane extensional nature gives rise to a significantly wave mode, frequency and direction dependent sensitivity. This can limit their application, but can also potentially be exploited for greater wave mode control. A method for simulating the output from hypothesised transducer behaviour is shown and validated for the MFC. This allows their behaviour to be predicted for new structures. It is shown that their frequency response can depend on the waveguide and can vary with direction, which can lead to wave mode transmission and reception characteristics that may be advantageous for some methods of application and detrimental to others. A novel method of adapting a flexible transducer, such as the MFC, has been developed and its characterisation is given. It is shown that through the use of a decoupling membrane, an MFC can be caused to have very different wave mode sensitivity characteristics whilst retaining their light and flexible nature. These altered characteristics are favourable for applications where shear horizontal wave modes are required. Both fully coupled MFC transducers and the adapted MFC transducers are considered for application to pipeline testing. Fully coupled MFC transducers are used for inspection using longitudinal waves, whilst the adapted MFC transducers are used with torsional waves. These arrays are compared to a current commercial tool.
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Lane, Christopher John Leslie. "The development of a 2D ultrasonic array inspection for single crystal turbine blades." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.651312.
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The aim of this thesis is to design and evaluate a non-destructive evaluation (NDE) system for the inspection of single crystal turbine blades. Turbine blades are the components within jet-engines that convert the hot, high-pressure gas exiting the combustion stage into mechanical power. During operation, these components are highly stressed and are surrounded by extremely high gas temperatures. As such, there is the potential for defects to initiate in-service. One way to ensure the structural integrity of these engine components is by periodically inspecting them for defects. The ability of the inspection to be performed in situ is highly advantageous, as this eliminates the cost and time delay associated with removing the turbine blades from the engine prior to inspection. A 20 ultrasonic phased array system was chosen for this project, as these systems can perform rapid volumetric inspections whilst being portable enough to be used in situ. Modem turbine blades are manufactured from single crystal nickel-based superalloys for the excellent mechanical properties these materials exhibit at elevated temperatures. However, these materials are elastically anisotropic. The propagation of ultrasonic waves through anisotropic materials is far more complex than the isotropic case. This causes significant difficulties when inspecting anisotropic single crystal components with ultrasonic arrays. Therefore, analytical models are developed to predict the propagation of ultrasonic waves in anisotropic materials. These models are used to correct an ultrasonic imaging algorithm to account for the anisotropic behaviour. To implement the corrected algorithm effectively, the orientation of the crystal in the component under inspection must be known. Therefore, crystallographic orientation methods using 20 ultrasonic arrays are developed and evaluated. The corrected algorithms and crystallographic orientation methods are used to develop an in situ 20 ultrasonic array inspection for a specific high-pressure single crystal turbine blade. The inspection is designed to detect and size cracking in the root section of the turbine blade. The developed inspection system is fully evaluated in a quantitative manner for its defect detection sensitivity and sizing capability.
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Damaj, Walid Taha. "Ultrasonic inspection of concrete structures to detect the condition of embedded steel components." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332656.
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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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Wang, Xiaoyue. "Integrated control systems for robotic NDT of large and remote surfaces." Thesis, London South Bank University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323885.
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Van, Deventer Christoffel Gerhardus. "Guidelines for predicting the remaining life of underground pipe networks that are subjected to the combined effects of external corrosion and internal pressure." Diss., Pretoria : [s.n.], 2002. http://upetd.up.ac.za/thesis/available/etd-10312005-113656/.
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Kojimoto, Nigel Costello. "Ultrasonic inspection methods for defect detection and process control in roll-to-roll flexible electronics manufacturing." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101811.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 97-100).
Roll-to-roll flexible electronics manufacturing technologies require new sensing and measurement capabilities for defect detection and process control. This body of work investigates the use of ultrasound, specifically Lamb and longitudinal waves, as a sensing modality and measurement technique for thin film roll-to-roll manufacturing. A variety of custom wedges were designed and machined from multiple materials to test their suitability at launching ultrasonic Lamb waves along Polyethylene Terephthalate (PET) film. Using hydrogel wedges, the fundamental antisymmetric (Ao) Lamb wave mode was successfully propagated a distance of 2 cm. ABS wedges were found to initiate longitudinal waves, which were detected at a distance of 5 cm. InstronTM based extension-tensile experiments revealed that the longitudinal wave is affected by tension in the PET, exhibited by a general increase in attenuation and a decrease in wave speed during plastic deformation; such variation may have process control applications.
by Nigel Costello Kojimoto.
S.M.
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Kocak, Okan Okay. "Defect Assessment Of Spot Welds By Ndi." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1027382/index.pdf.
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Resistance spot welding is used frequently as a successful joining method for
a variety of work commonly in automotive and other manufacturing
processes. Spot weld nugget is generally hidden between two sheets,
causing its inspection difficult and expensive. Undersized nuggets, brittle or
cracked nuggets, and excessive indentation of electrodes reveals the lack of
fusion between the parts that can make the weld sub-standard.
Visual inspection, pry testing and physical teardown with chisel and hammer
method or a combination of them are being used traditionally. However, this
study presents a more effective nondestructive inspection method based
upon an ultrasonic pulse-echo technique. The theory of the technique together with the experimental verification are presented and its advantages over the other destructive and nondestructive
techniques are considered.
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Geremia, Giovani. "Sistema autônomo de inspeção de dutos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/72898.
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A principal forma de transporte de petróleo e derivados, entre outras substâncias, são os dutos, e um dos processos críticos relacionados é a sua inspeção periódica, que é necessária e obrigatória, de alto custo devido à sua complexidade, e que na maioria das vezes são realizadas manualmente, em procedimentos demorados, pouco confiáveis e insalubres devido ao meio e aos riscos a que o trabalhador é exposto. Este trabalho tem o objetivo de testar diversas aplicações e situações de um sistema de inspeção de dutos robótico desenvolvido. O interesse de observação foi a praticidade e facilidade de montagem e desmontagem do equipamento sobre a tubulação, a agilidade dos graus de liberdade propostos para o sistema, a flexibilidade do equipamento para utilização de diferentes métodos de inspeção, a rapidez e confiabilidade dos resultados de inspeção por ultrassom para varredura de espessuras em busca de corrosão generalizada interna de uma tubulação e a capacidade de precisão e resolução desta inspeção por ultrassom. Para abordar estes pontos, foram realizados uma série de testes, inicialmente para verificação do bom funcionamento dos graus de liberdade do sistema, e posteriormente com métodos diferenciados de inspeção, como testes para medição geométrica externa de uma tubulação, testes com sistemas de ultrassom embarcado em laboratório e em campo com diferentes malhas de inspeção e com um ou múltiplos cabeçotes, e para diferentes tubulações e formatos de redução de espessuras de parede na tubulação.The main way for transporting petroleum and substances alike is through ducts, and one of the most critic processes involved is the periodic inspection, wich is necessary and mandatory, with a high cost due to its complexity, and, in most cases, done manually in long time consuming procedures and with little reliability and high risk for the workers involved. This work is intended to test various situations of a robotic inspection system developed. The observation interest was the practicity and easiness of assembling and disassembling the equipment on the pipes, the agility of degrees of freedom proposed for the system, the flexibility of the equipment for the use in different methods of inspection, the quickness and reliability of the results by ultrasound for scanning different thicknesses of a duct in search of "generalized internal corrosion" and the level of precision and resolution of this ultrasound scan. To approach this topics, a series of test were conducted, at first to check if the degrees of freedom of the system were working as intended and afterwards with different methods of inspection, such as external geometric measurements of the pipes, tests with onboard ultrasound systems in lab and on the field with different inspection grades and with one or multiple ultrasound sensors, and for different kinds of pipes and thickness reduction shapes of the pipe's walls.
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Coccia, Stefano. "Ultrasonic guided waves for structural health monitoring and application to rail inspection prototype for the Federal Railroad Administration." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3283950.
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Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed March 14, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 271-281).
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Baradi, Divyank. "Control strategies and inspection methods for welded part." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-16383.
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Present and future demonstrator designs were used to demonstrate the quality assurance of welds. The NDT methods tested on prototype demonstrator parts are: visual inspection, radius gauges, throat size gauge, liquid-penetrant testing, magnetic particle testing and ultrasonics with pulse echo and phased array. The other methods like eddy current, time of flight diffraction, radiography, impression test, macro test and infrared thermographs are currently being analyzed along with their inspection costs. The control plans for present and future designs with corresponding present and future NDT methods are suggested to minimize a shift in process. Magnetic particle testing revealed a lack of fusion and cracks for fillet welds, whereas ultrasonic pulse echo and phased array identified an internal lack of fusion, inner pores/slag inclusions on butt welds. Ultrasonic PAUT & TOFD could be used for accurate defect identification and thermography for online identification of lack of penetration, depth of penetration and weld parameters.Weight reduction by improved weld quality (WIQ)
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Zhang, Lizheng. "Development of Microelectronics Solder Joint Inspection System: Modal Analysis, Finite Element Modeling, and Ultrasound Signal Processing." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-05152006-133722/.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2007.Ume, Charles, Committee Chair ; Book, Wayne, Committee Member ; Michaels, Jennifer, Committee Member ; Sitaraman, Suresh, Committee Member ; Tsui, Kwok-Leung, Committee Member ; Goyal, Deepak, Committee Member.
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Yang, Jin. "Quality inspection and reliability study of solder bumps in packaged electronic devices [electronic resource] : using laser ultrasound and finite element methods." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26593.
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Consumer demands are driving the current trend in the microelectronics industry to make electronic products that are miniature, fast, compact, high-density, reliable and low-cost. The use of surface mount devices (SMDs) has helped to decrease the size of electronic packages through the use of solder bump interconnections between the devices and the substrates/printed wiring boards (PWBs). Solder bumps act as not only mechanical, but also electrical interconnections between the device and the substrate/PWB. Common manufacturing defects ¨C such as open, cracked, missing, and misaligned solder bumps ¨C are difficult to detect because solder bumps are hidden between the device and the substrate/PWB after assembly. The reliability of packaged electronic devices in storage and usage is a major concern in the microelectronics industry. Therefore, quality inspection of solder bumps has become a critical process in the microelectronics industry to help ensure product quality and reliability.
In this thesis, a methodology for quality evaluation and reliability study of solder bumps in electronic packages has been developed using the non-destructive and non-contact laser ultrasound-interferometric technique, finite element and statistical methods in this research work. This methodology includes the following aspects: 1) inspection pattern ¨C specific inspection patterns are created according to inspection purpose and package formats, 2) laser pulse energy density calibration ¨C specific laser pulse power and excitation laser spot size are selected in terms of package formats, 3) processing and analysis methods, including integrated analytical, finite element and experimental modal analyses approach, advanced signal processing methods and statistical analysis method, 4) approach combining modal analysis and advanced signal processing to improve measurement sensitivity of laser ultrasound-interferometric inspection technique, and 5) calibration curve using energy based simulation method and laser ultrasound inspection technique to predict thermomechanical reliability of solder bumps in electronic packages.
Because of the successful completion of the research objectives, the system has been used to evaluate a broad range of solder bump defects in a variety of packaged electronic devices. The development of this system will help tremendously to improve the quality and reliability of electronic packages.
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Charlesworth, Chris. "Ultrasonic phased array testing in the power generation industry : novel wedge development for the inspection of steam turbine blades roots." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/49401/.
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The thesis presented herein comprises of the work undertaken to research novel methods of Phased array ultrasonic inspection of complex steam turbine blade roots as found in the power generation industry. The research was conducted as part of the Engineering Doctorate scheme, administered by the Research Centre for Non-Destructive Evaluation (RCNDE), in conjunction with RWE npower and the University of Warwick. Steam turbine blades, and in particularly last stage blades of low pressure steam turbines, are amongst the most highly stressed components on a power generating plant. Two of the most common blade root fixing types include ‘curved axial entry fir tree roots’ (CAEFTR), and axial pinned roots, both of which are prone to cracking due to the high stresses to which they are subjected under operating conditions. Failure of the blade root fixings of such components, leading to the release of the blades, has historically led to the catastrophic failure and destruction of the whole turbine; the cost of collateral damage to plant components and the loss in generating income are seconded only by the risk these failures pose to life. Due to the high price of failure, NDT plays a critical part in the support and management of engineering maintenance, offering insight into the condition and integrity of turbine components through regular planned inspection regimes. It will be shown in this thesis how the invention of a novel continuous wedge, used to refract ultrasound into the critical regions of the blade roots, has significantly improved the ability to detect defects. Combined with the development of bespoke scanning frames these wedges facilitate the efficient and accurate acquisition of scanned data to assess the integrity of the component. By combining the latest reverse engineering, modelling and simulation tools with novel application of rapid prototyping, the author has been able to demonstrate significant reduction in design cycles whilst improving accuracy, sensitivity and repeatability of the applied inspections. Furthermore, application of this design philosophy has led to the development of inspection techniques which have facilitated the inspection of remote regions of the blade roots where manual access is limited or impossible. The developments and techniques invented during this research have been successfully deployed across numerous RWE npower and customer projects, leading to estimated savings in excess of £1m.
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Huber, Armin [Verfasser], and Markus [Akademischer Betreuer] Sause. "Numerical Modeling of Guided Waves in Anisotropic Composites with Application to Air-coupled Ultrasonic Inspection / Armin Huber ; Betreuer: Markus Sause." Augsburg : Universität Augsburg, 2021. http://d-nb.info/1230755314/34.
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Sengupta, Anandraj. "Effect of specimen geometry on ultrasound diffusion in cement-based aggregates." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22578.
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Zia, Tabari M. "Design, development and assessment of an automated ultrasonic inspection system in production and experimental analysis if tubular butt welds for identification and characterisation of weld defect." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376231.
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Pospíšil, Karel. "Projekt technologické linky pro čištění a nedestruktivní kontrolu vyráběných součástí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228211.
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Description of Ultrasonic Cleaning technology. Description of Non-destructive testing technology process. Design of Ultrasonic Cleaning equipment. Design of equipment for the ultrasonic cleaning machine. Design of non-destructive testing equipment (Liquid Penetrant Inspection and Magnetic Testing). Feasibility study of designed technologies and supporting processes.
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Felice, Maria Victoria. "Ultrasonic array inspections for complex defects." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687061.
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The aim of this thesis is to develop a simulation-assisted methodology for optimising ultrasonic array inspections and to apply it to an industrial problem. In particular, the focus is on inspections for complex defects and the motivation behind the work is an aerospace engine component that may suffer from stress corrosion cracking. Unlike fatigue cracks, these cracks are typically branched and are therefore difficult to detect with ultrasonic inspections. The development of the simulation-assisted methodology consists of two key parts. The first part is to implement a computer model that correctly simulates the interaction of ultrasound with complex cracks, while being efficient enough to be used in an optimisation exercise. An efficient Finite Element method and the Kirchhoff Approximation are compared with regards to their capability for simulating the ultrasonic scattering from complex cracks, and the Finite Element method is found to be preferable. This method is combined with ray tracing to obtain a hybrid model that simulates ultrasonic array data from the cracks and the complete model is successfully validated experimentally. The second part of the development of the methodology is to establish a process of obtaining real crack shapes to input into the hybrid model. The process which is developed involves the use of X-ray Computed Tomography to obtain high-resolution images of cracked parts and then segmenting the images. The computer model and real crack shape extraction process are used together to optimise the detection capability of an ultrasonic array inspection for the aerospace engine component. The signal-to-noise ratios obtained with a selection of array designs are compared with each other and with those obtained using a single element ultrasonic probe. The sizing capability of the array inspections is also investigated and the use of the Half-Skip Total Focusing Method to size cracks is analysed in detail.
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Bingham, Jill Paisley. "Ultrasonic guided wave interpretation for structural health inspections." W&M ScholarWorks, 2008. https://scholarworks.wm.edu/etd/1539623538.
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Structural Health Management (SHM) combines the use of onboard sensors with artificial intelligence algorithms to automatically identify and monitor structural health issues. A fully integrated approach to SHM systems demands an understanding of the sensor output relative to the structure, along with sophisticated prognostic systems that automatically draw conclusions about structural integrity issues. Ultrasonic guided wave methods allow us to examine the interaction of multimode signals within key structural components. Since they propagate relatively long distances within plate- and shell-like structures, guided waves allow inspection of greater areas with fewer sensors, making this technique attractive for a variety of applications.;This dissertation describes the experimental development of automatic guided wave interpretation for three real world applications. Using the guided wave theories for idealized plates we have systematically developed techniques for identifying the mass loading of underwater limpet mines on US Navy ship hulls, characterizing type and bonding of protective coatings on large diameter pipelines, and detecting the thinning effects of corrosion on aluminum aircraft structural stringers. In each of these circumstances the signals received are too complex for interpretation without knowledge of the guided wave physics. We employ a signal processing technique called the Dynamic Wavelet Fingerprint Technique (DFWT) in order to render the guided wave mode information in two-dimensional binary images. The use of wavelets allows us to keep track of both time and scale features from the original signals. With simple image processing we have developed automatic extraction algorithms for features that correspond to the arrival times of the guided wave modes of interest for each of the applications. Due to the dispersive nature of the guided wave modes, the mode arrival times give details of the structure in the propagation path.;For further understanding of how the guided wave modes propagate through the real structures, we have developed parallel processing, 3D elastic wave simulations using the finite integration technique (EFIT). This full field, numeric simulation technique easily examines models too complex for analytical solutions. We have developed the algorithm to handle built up 3D structures as well as layers with different material properties and surface detail. The simulations produce informative visualizations of the guided wave modes in the structures as well as the output from sensors placed in the simulation space to mimic the placement from experiment. Using the previously developed mode extraction algorithms we were then able to compare our 3D EFIT data to their experimental counterparts with consistency.
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Krejčí, Martin. "Nedestruktivní zkoušení odlitků ozubených kol." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228720.
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This diploma thesis resolves aplication of particular non-destructive testing methods while producing castings of steel wheels and quality control of this process. There are described fundamentals of flaw detection, determination of flaw-generation cause and suggestions for optimalization of casting process and increasing of its quality.
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Malatesta, Michelangelo Maria <1992>. "Embedded systems and advanced signal processing for Acousto- Ultrasonic Inspections." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10332/1/PhDTesis_Malatesta_Finalv2.pdf.
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Non Destructive Testing (NDT) and Structural Health Monitoring (SHM) are becoming essential in many application contexts, e.g. civil, industrial, aerospace etc., to reduce structures maintenance costs and improve safety. Conventional inspection methods typically exploit bulky and expensive instruments and rely on highly demanding signal processing techniques. The pressing need to overcome these limitations is the common thread that guided the work presented in this Thesis.
In the first part, a scalable, low-cost and multi-sensors smart sensor network is introduced. The capability of this technology to carry out accurate modal analysis on structures undergoing flexural vibrations has been validated by means of two experimental campaigns. Then, the suitability of low-cost piezoelectric disks in modal analysis has been demonstrated. To enable the use of this kind of sensing technology in such non conventional applications, ad hoc data merging algorithms have been developed.
In the second part, instead, imaging algorithms for Lamb waves inspection (namely DMAS and DS-DMAS) have been implemented and validated. Results show that DMAS outperforms the canonical Delay and Sum (DAS) approach in terms of image resolution and contrast. Similarly, DS-DMAS can achieve better results than both DMAS and DAS by suppressing artefacts and noise. To exploit the full potential of these procedures, accurate group velocity estimations are required. Thus, novel wavefield analysis tools that can address the estimation of the dispersion curves from SLDV acquisitions have been investigated. An image segmentation technique (called DRLSE) was exploited in the k-space to draw out the wavenumber profile. The DRLSE method was compared with compressive sensing methods to extract the group and phase velocity information. The validation, performed on three different carbon fibre plates, showed that the proposed solutions can accurately determine the wavenumber and velocities in polar coordinates at multiple excitation frequencies.
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Smith, P. "A recording and presentation system for manual ultrasonic inspections using a speech recognition interface." Thesis, University of the West of Scotland, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265930.
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Reliability and repeatability are fundamental concepts in ultrasonic nondestructive testing. An inspection technique must be able to accurately detect, characterize, position and size any defect indication. In manual ultrasonic inspection, however, the operator can be a frequent source of error. Mistakes often arise due to the volume of information the operator must memorize and process. Existing solutions require mechanical probe manipulators that restrict the operator's movements and often require changes to trusted methods and procedures. The aim of this research programme was to investigate the potential of a computer system that assists the operator in the analysis of echodynamic patterns. The system allows the operator to record A-scan sequences, store them to disk, and recall them for review. The system's flexible user interface gives the operator freedom to retain existing inspection practices, in addition to the benefits of computer recording. A novel feature of the system was a speech recognition system to provide hands-free control, which minimizes disruption to the flow of the inspection. Trials were conducted to assess the recognizer's reliability under various conditions. The trials showed that focusing upon echodynamic pattern analysis is a valid and useful approach. Only a limited trial was conducted, however, so the research program was not able to conclusively show that the system will reduce operator errors or improve inspection reliability. In user testing sessions, operators agreed that such a system would be helpful during a manual inspection and there were few objections to the imposition of new hardware. Users quickly became used to the speech recognizer, and the speed of interaction and 'flow' of inspection were greatly enhanced. The author suggests that a computerized assistant is worthy of further development, and has the potential to be a valuable tool in manual ultrasonic inspection.
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Anagnostopoulos, Eleftherios. "Modélisation de la génération d'ultrasons par laser : application à l'inspection de composants aéronautiques métalliques et composites." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0043/document.
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Le Contrôle Non Destructif par ultrasons-laser est une technique attractive pour l'industrie aéronautique de par son caractère entièrement sans contact et permet l'inspection rapide etefficace de composants mécaniques complexes. L'objectif de ces travaux de thèse concerne lamodélisation de la génération d'ultrasons par laser dans les composants aéronautiques, métalliques etcomposites, de géométrie bicouche. Nous cherchons en effet à étudier l’influence sur le mécanisme degénération ultrasonore d’un revêtement tel qu’une couche superficielle de peinture ou de résine. Dansun premier chapitre, nous proposons une modélisation semi-analytique unidimensionnelle de lagénération et propagation d’ultrasons par laser dans une géométrie bicouche au travers de deuxapproches. L’apport en termes de coût numérique d’une des deux méthodes nous conduit à montrerleur équivalence en traitant rigoureusement le problème des conditions aux limites. Dans les troisderniers chapitres, des modèles de directivité des ondes ultrasonores générées par laser sont proposésdans des géométries de complexité croissante, d’un matériau homogène jusqu’au cas d’un bicoucheen passant par le cas intermédiaire de deux demi-espaces aux propriétés optiques variées. L’influencede l’épaisseur d’une couche superficielle de résine à la surface d’un matériau composite est trèsnettement mise en évidence et expliquée à l’aide des différents outils développés. Nous discutonségalement de l’intérêt du calcul de ces directivités dans la prise en compte des sources élastiquesengendrées par laser dans un formalisme de type rayon utilisé par le logiciel dédié au contrôle nondestructif CIVA développé au CEAThe laser-ultrasonic technique is an attractive Non Destructive Testing technology forthe aviation industry. Indeed, its non-contact ultrasonic generation process could allow inspectingcomplex mechanical part at high sampling rates. The purpose of this work consists in the modelling ofthe generation of ultrasonic waves by a laser pulse in metallic or composite materials in bilayer geometry.In this work, we seek to analyze in detail the influence of coatings on the ultrasonic generation processsuch as paint or resin coatings usually used in industrial parts. In a first chapter, we propose two differentapproaches of a semi-analytical modelling of the generation and propagation of ultrasonic waves in aone-dimensional assumption of a bilayer sample. As one of them handles shorter computation times,we decide to rigorously show the equivalence of these different approaches focusing on the boundaryvalue problem. In the three last chapters, different models of the directivity patterns of ultrasonic wavesgenerated by a laser pulse are given in geometries of increasing complexity, from a homogeneousmaterial to a bilayer considering the intermediate case of two half-spaces of various optical properties.As a result, we clearly show the influence of a superficial skin layer on the laser-generated ultrasoundsemitted in composite materials. We also discuss briefly on the interest of the directivity patterns to modelelastic sources generated by laser in a ray formalism used in the CIVA software dedicated to NDTsimulations and developed at CEA
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Ostiguy, Pierre-Claude. "Effet de la composition des matériaux composites sur la caractérisation et détection par ondes de Lamb." Mémoire, Université de Sherbrooke, 2012. http://hdl.handle.net/11143/5524.
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Les matériaux composites sont de plus en plus utilisés en aéronautique. Leurs excellentes propriétés mécaniques et leur faible poids leur procurent un avantage certain par rapport aux matériaux métalliques. Ceux-ci étant soumis à diverses conditions de chargement et environnementales, ils sont susceptibles de subir plusieurs types d'endommagements, compromettant leur intégrité. Des méthodes fiables d'inspection sont donc nécessaires pour évaluer leur intégrité. Néanmoins, peu d'approches non destructives, embarquées et efficaces sont présentement utilisées. Ce travail de recherche se penche sur l'étude de l'effet de la composition des matériaux composites sur la détection et la caractérisation par ondes guidées. L'objectif du projet est de développer une approche de caractérisation mécanique embarquée permettant d'améliorer la performance d'une approche d'imagerie par antenne piézoélectrique sur des structures composites et métalliques. La contribution de ce projet est de proposer une approche embarquée de caractérisation mécanique par ultrasons qui ne requiert pas une mesure sur une multitude d'échantillons et qui est non destructive. Ce mémoire par articles est divisé en quatre parties, dont les parties deux à quatre présentent les articles publiés et soumis. La première partie présente l'état des connaissances dans la matière nécessaire à l'accomplissement de ce projet de maitrise.Les principaux sujets traités portent sur les matériaux composites, propagation d'ondes, la modélisation des ondes guidées, la caractérisation par ondes guidées et la surveillance embarquée des structures. La deuxième partie présente une étude de l'effet des propriétés mécaniques sur la performance de l'algorithme d'imagerie Excitelet. L'étude est faite sur une structure isotrope.Les résultats ont démontré que l'algorithme est sensible à l'exactitude des propriétés mécaniques utilisées dans le modèle. Cette sensibilité a également été explorée afin de développer une méthode embarquée permettant d'évaluer les propriétés mécaniques d'une structure. La troisième partie porte sur une étude plus rigoureuse des performances de la méthode de caractérisation mécanique embarquée. La précision, la répétabilité et la robustesse de la méthode sont validés à l'aide d'un simulateur par FEM.Les propriétés estimées avec l'approche de caractérisation sont à moins de 1% des propriétés utilisées dans le modèle, ce qui rivalise avec l'incertitude des méthodes ASTM. L'analyse expérimentale s'est avérée précise et répétable pour des fréquences sous les 200 kHz, permettant d'estimer les propriétés mécaniques à moins de 1% des propriétés du fournisseur. La quatrième partie a démontré la capacité de l'approche de caractérisation à identifier les propriétés mécaniques d'une plaque composite orthotrope.Les résultats estimés expérimentalement sont inclus dans les barres d'incertitude des propriétés estimées à l'aide des tests ASTM. Finalement, une simulation FEM a démontré la précision de l'approche avec des propriétés mécaniques à moins de 4 % des propriétés du modèle simulé.
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Fnine, Abdelilah. "Ausculation de la peau du béton par ondes ultrasonores haute fréquence." Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-Fnine.pdf.
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Les ouvrages de génie civil en béton armé sont destinés à assurer un certain nombre de fonctions souvent pendant plusieurs siècles. Les armatures en acier sont protégées de l'extérieur par quelques centimètres de béton appelés épaisseur d'enrobage, couche protectrice très importante pour la durée de vie. De nombreuses agressions chimiques et physiques sont capables d'altérer cette protection, ce qui conduit à la corrosion des armatures, à de la fissuration ou de la microfissuration, et à l'augmentation de la porosité. L'intérêt principal du contrôle non destructif (CND) comme outil d'auscultation est qu'il permet sans toucher à l'intégrité de l'ouvrage de réaliser des investigations (même répétées dans le temps). L'originalité du travail est d'utiliser les ondes ultrasonores de surface (OS) se propageant à la surface du béton, dont la propagation est perturbée par des obstacles (fissures, trous,. . . ) ou des modifications des propriétés du matériau (hétérogénéités). Il en découle des modifications de vitesse, d'atténuation et d'amplitude. L'analyse est conduite à des fréquences de 0,5 à 1 MHz, gamme de fréquence inhabituelle dans le domaine du génie civil, mais qui s'impose au vu de la faible épaisseur de la couche dégradée et de la taille des discontinuités engendrées par la dégradation. Les ondes de Rayleigh sont adaptées à notre problématique puisque elles sont les seules utilisables si une seule face de l'ouvrage est accessible et leur profondeur de pénétration est en rapport avec leur longueur d'onde et donc avec la fréquence employée. Le travail a permis de passer d'un dispositif acoustique avec contact à un robot émetteur-récepteur sans contact automatisé (gain de temps, répétition des mesures sur une même zone, moins de perte d'énergie due au couplage, meilleure précision des mesures). Des programmes de traitement originaux des signaux acoustiques permettent l'estimation des paramètres principaux. La méthode Slant Stack (méthode de mesure de la vitesse) permet une détermination précise de la caractéristique de la dispersion. D'autre part, il a été mis en évidence la possibilité de distinguer les classes de résistance du béton, de détecter une zone carbonatée, de détecter une fissure, de localiser l'amorçage d'une fissure avant qu'elle ne soit visible. Cependant, la technique n'est pas capable de distinguer la différence entre un remplissage de la porosité par une eau chlorée ou non. De nombreuses études ont été menées aussi bien en laboratoire que sur ouvrages réels. Les différents essais réalisés (en laboratoire et sur site) ont toujours fait l'objet d'un croisement des techniques qui montre la plus-value apportée par la combinaison de plusieurs méthodes.
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Bakkali, Mohammed Marouane El. "Modélisation des contrôles non-destructifs par ondes ultrasonores guidées. Application aux contrôles de canalisations." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0004/document.
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La thèse s’inscrit dans les travaux du CEA LIST pour développer dans la plate-forme CIVA un module simulant le contrôle non-destructif (CND) par ondes ultrasonores guidées ; elle est dédiée au développement et à la validation de modèles simulant l’inspection de canalisations et se focalise sur le cas de canalisations comportant un ou plusieurs coudes. Pour prédire l’effet de la courbure sur les ondes guidées, une extension en coordonnées curvilignes de la méthode des éléments finis semi-analytiques est réalisée pour calculer les modes se propageant dans un coude, par résolution d’un système d’équations aux valeurs propres restreint à la section du guide. Ce développement a aidé à comprendre les effets de distorsion des champs ultrasonores et de décalage des fréquences de coupures dus à la courbure. La diffraction des ondes à la jonction entre un tube droit et un coude est ensuite calculée par raccordement modal donnant la matrice de diffraction de la jonction ; les éléments de la matrice s’obtiennent par évaluation numérique d’intégrales à la surface de la jonction. Les matrices de diffractions locales sont enfin combinées à des matrices de propagation pour rendre compte de la présence de plusieurs diffracteurs sur la canalisation, sous forme d’une matrice globale de diffraction. Le coût minimal de son calcul permet d’étudier l’influence des paramètres de contrôle et de les optimiser. Les modèles sont validés en comparant leurs prédictions avec des résultats numériques et expérimentaux de la littérature et des mesures faites au CETIM sur maquettes industrielles. Intégrés à la plate-forme CIVA, ils étendent les possibilités du module de simulation du CND par ondes guidéesThe thesis is in the framework of developments made at CEA LIST of a module of the CIVA platform to simulate nondestructive testing (NDT) by ultrasonic guided waves; it is dedicated to the development and the validation of models simulating the examination of pipelines and is focussed on the case of pipeline comprising one or several elbows. To predict effects due to the curvature on guided waves, an extension in curvilinear coordinates of the semi-analytic finite element method is worked out to compute modes propagating in an elbow, by solving an eigen system restricted to the guide section. This development allows us to better understand effects due to the curvature such as displacement field distortions or cut-off frequencies splits. The scattering of waves at the junction between a straight tube and an elbow is then computed by means of the mode-matching method, leading to the modal scattering matrix of the junction; matrix elements are obtained by numerical evaluation of integrals over the junction surface. Local scattering matrices are finally combined to propagation matrices to account for the presence of several scatterers in the pipeline, to form a global scattering matrix. Its minimal computation cost allows us to study the influence of the parameters of the testing configuration and to optimize them. Models are validated by comparing their predictions to numerical and experimental results of the literature and to measurements made at CETIM on industrial mock-ups. Integrated in the platform CIVA, the developed models extend the capabilities of the guided wave NDT module
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Kao, Kuang-Chien, and 高光前. "Automatic Ultrasonic System for Flaw Inspection." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/49636931409597561039.
Full textAbstract:
碩士國立屏東商業技術學院
資訊管理系
92
Ultrasound has many important applications in nondestructive testing. Since ultrasonic signal can penetrate many materials, it is widely used for detection of flaws. The evaluations of welding are the main purpose of this paper. The use of ultrasound is limited by several interferences, such as geometric inter-face, coarse grain, mode conversion and ringing. It will be practically difficult to perform evaluation if the originally received ultrasonic signal is used directly as false judgment may be obtained. This paper will use the methods of signal processing and wavelet transform to reject noisy signal and detect the position and relative information of flaws. Owing to effect that the sound beam will diverge in far field, the flaw information will be distorted in 2-D or 3-D ultrasonic images. Synthetic aperture focusing technique (SAFT) uses the methods similar to sensor fusion to reduce the distortion and increase the accuracy for evaluation. The appraisal of the size of the flaw utilizes the distance between the flaw and transducer. The size of flaw can then be measured according to a proportionally transfer function. We also performed measurement on various types of side-drilled holes and cracks. Simulations show that our method provides very effective results.
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Tien, Y. F., and 田亦凡. "High Speed Ultrasonic Image Inspection System." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/49369719312725345137.
Full textAbstract:
碩士國立成功大學
機械工程學系
89
Ultrasound is a very important tool which has many applications in biological, medical and engineering practices. One can use ultrasound to measure the wave velocity and find the physical properties including Young’s modulus, shear modulus, etc. Ultrasound is also used for detecting cracks and voids in materials in a non-destructive way, so that the defects can be found out and characterized in advance. This thesis introduce a ultrasonic scanning system which consists of a transducer, a peak detector, a water tank, a motorized X-Y axis scanning frame, a servo-motion control card, and a personal computer. The transducer is used to excite and receive ultrasonic waves at a frequency of 5 MHz. The sample is placed in a tank filled with water, which couples the ultrasound transmitted by the transducer to the sample under investigation. The X-Y axis motors are controlled by a PC-based motion control card. An ultrasonic image of the sample, which contains useful material information, can be obtained by an analog-digital data acquisition card which is also PC-based. The goal of this work is to promote the scanning speed and the performance of the ultrasound image scanning system so that it can meet the industrial standards and even compete with existing commercial products. In this thesis, Microsoft Visual C++ 6.0 has been chosen to develop the software and all other functions. The reason is that it has the properties of both high-level and low-level programming capability, and it is also an Object-Oriented Programming language which is easy to develop in a Windows system. Furthermore, Visual C++ program develop tool are widely used in industry.
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Chi-TseKuo and 郭奇澤. "An FPGA-Based Ultrasonic Image Scanning System and Non-immersed Ultrasonic Inspection." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/94422215381460325358.
Full textAbstract:
碩士國立成功大學
機械工程學系
102
This study constructs a Field Programmable Gate Array (FPGA) based non-destructive inspection system and a non-immersion ultrasonic scanning device. The inspection system exploits the high integration and flexibility of FPGA for real-time motion monitoring, acoustic trigger, data acquisition and signal analysis and reduces the host system loading by sending shortest data. Furthermore a concise concept of non-immersion ultrasonic scanning device is designed for non-destructive testing specimen that is apt to rust. This scanning system realizes a multiple profile and flatness correction ultrasonic signal measurement with FPGA chip. The FPGA programs use 100 multiple gates to split signal for realizing multiple profiles and two-step analysis to fix the sample’s flatness problem. The available scanning modes include A-scan, B-scan, P-scan, C-scan, X-scan, G-scan, and S-scan. A horizontal deviation less than 0.23 mm or 5.2 degree can be fixed by the surface detection function in the FPGA. The maximum scanning speed reaches 2000 mm/s. The vertical and horizontal scanning resolution of simple specimen is 3 μm and 20 μm respectively and the horizontal scanning resolution of complex large curvature specimen is 50 μm. The nominal sampling rate is 22 kHz and the average sampling rate is 8 kHz. Its performance is compatible with some commercial models of ultrasonic inspection systems. For non-immersion scanning, a special device is developed in order to couple the specimen surface with very little water for scanning over a 220 mm × 220 mm large area. The results of non-immersion and immersion resolution and image quality are quite the same. However, if the specimen is not well leveled over a wide range, the signals will show vertical deviations.