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Lowea, D. "Methods of non-destructive testing." Thesis, Київський національний університет технологій та дизайну, 2019. https://er.knutd.edu.ua/handle/123456789/14600.
Повний текст джерела
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Десятниченко, Алексей Владимирович. "Электромагнитно-акустический толщиномер для контроля металлоизделий с диэлектрическими покрытиями". Thesis, НТУ "ХПИ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/17117.
Повний текст джерелаАнотація:
Диссертация на соискание ученой степени кандидата технических наук по специальности 05.11.13 – приборы и методы контроля и определения состава веществ. – Национальный технический университет "Харьковский политехнический институт", Харьков, 2015.
Диссертация посвящена решению важной научно-практической задачи обеспечения ультразвукового контроля толщины металлоизделий электромагнитно-акустическим методом при наличии диэлектрических покрытий (зазоров) толщиной до 10 мм. В работе выполнен анализ существующих акустических методов и устройств для измерения толщины, которые широко используются в отечественной и зарубежной промышленности, рассмотрены основные их преимущества и недостатки. Методы разделяются по типу контакта датчика с объектом контроля на два основные класса: контактные и бесконтактные. Бесконтактные на сегодняшний день являются наиболее перспективными. К ним относятся методы, основанные на: воздушно акустической связи, термо- и оптико-акустическом эффектах, а также на эффектах электрического и электромагнитного полей. По результатам анализа недостатков приведенных методов, выделен наиболее перспективный – ЭМА метод. Рассмотрены вопросы выбора оптимального сигнала для возбуждения акустических колебаний ЭМА методом. Приведены расчеты принимаемой энергии для общего случая при зеркальной схеме контроля, когда передающий и приемный датчики не располагаются соосно по высоте изделия. Рассмотрены модели расчетов для зеркально теневой схемы контроля, отдельно для режимов излучения ЭМАП в виде длинных и коротких импульсов. Дан анализ целесообразности использования вариантов зондирующего сигнала с различными соотношениями длины импульсов и расстояний между ними. Рассмотрена электрическая модель выходного каскада усилителя зондирующего сигнала и датчика, описаны особенности ее работы. Приведены результаты экспериментальных исследований и разработок, направленных на повышение качества и производительности контроля толщины с использованием ЭМА метод возбуждения и приема акустических колебаний. Представлена конструкция макета ЭМА преобразователя для контроля металлоизделий при наличии зазора между датчиком и изделием. Рассмотрены вопросы построения передающего и приемного аналоговых трактов, приведены схемотехнические и конструктивные решения. Приведены результаты исследований зависимости амплитуды сигнала на генерирующей обмотке ЭМАП от напряжения питания усилителя. Проведены исследования зависимости уровня полезного сигнала он напряжения на передающей обмотке датчика. Исследовано влияния зазора на уровень полезного сигнала. Приведены результаты зависимости длительности «мертвой» зоны от зазора и способы ее снижения. Определены факторы, влияющие на точность контроля. Разработан толщиномер основанный на электромагнитно акустическом методе возбуждения и приема акустических волн, приведены результаты этой разработки. Рассмотрены особенности построения его составных частей. Рассмотрены алгоритмы цифровой обработки принятого сигнала. Проведена оценка метрологических характеристик разработанного прибора, изготовлен контрольный образец для метрологического обеспечения толщиномера. Приведено сравнение нового прибора с существующими аналогами.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.11.13 – Devices and methods of testing and materials structure determination. – National technical university "Kharkiv Politechnical Institute", Kharkiv, 2015. Thesis is devoted to solution of important theoretical and practical task to ensure ultrasound control of the metal products thickness by using electromagnetic-acoustical method in cases of dielectric coatings (gaps) with thickness up to 10 mm. Work includes analysis of existing acoustic methods and devices for thickness measurement, their main advantages and disadvantages are reviewed. Based on the results of analysis of the given disadvantages, the most advanced ways was set off - electromagnetic-acoustical (EMA) method. The problems of selection of the optimal signal agitate sonorous vibrations by EMA method were reviewed. Calculations of the taken energy are given for the analysis of the practicability to use variants of probing signal. Electric model of amplifier output stage of probing signal and sensor is reviewed, peculiarities of its operation are described. Results of researches and developments dedicated to increase thickness measurement quality and efficiency are given. Matters to build of the transmitting and receiving analog tracts are reviewed. The signal level dependence on voltage research on sensor's transmitting winding are conducted. Impact of a gap on the signal level was examined. Results of the dependence of dead spot length on a gap and methods to its reduction are given. Factors affecting accuracy of control are determined. EMA thickness gauge was designed. The main factors of design are examined. The digital processing algorithm of the received data was reviewed. Metrological characteristics of the developed device were made.
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Десятніченко, Олексій Володимирович. "Електромагнітно-акустичний товщиномір для контролю металовиробів з діелектричними покриттями". Thesis, НТУ "ХПІ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/17045.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.11.13 – прилади і методи контролю та визначення складу речовин. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2015.
Дисертація присвячена вирішенню важливої науково-практичної задачі, яка полягає у забезпеченні ультразвукового контролю товщини металовиробів електромагнітно-акустичним методом при наявності діелектричних покриттів (зазорів) товщиною до 10 мм.
У роботі виконано аналіз існуючих акустичних методів і пристроїв для вимірювання товщини, розглянуті основні їх переваги та недоліки. За результатами аналізу недоліків наведених методів, виділений найбільш перспективний – ЕМА метод.
Розглянуто питання вибору оптимального сигналу для збудження акустичних коливань ЕМА методом. Наведено розрахунки прийнятої енергії. Дано аналіз доцільності використання різних варіантів сигналу зондування. Розглянуто електричну модель вихідного каскаду підсилювача сигналу зондування і датчика, описано особливості її роботи.
Наведено результати експериментальних досліджень і розробок спрямованих на підвищення якості та продуктивності контролю товщини. Представлена конструкція макета ЕМА перетворювача для контролю металовиробів при наявності зазору між датчиком і об'єктом. Розглянуто питання побудови передавального і приймального аналогових трактів, наведені конструктивні рішення. Досліджено залежність амплітуди сигналу на генеруючої обмотці ЕМАП від напруги живлення підсилювача. Проведено дослідження залежності рівня корисного сигналу він напруги на передавальній обмотці датчика. Досліджено впливу зазору на рівень корисного сигналу. Наведено результати залежності тривалості "мертвої" зони від зазору і способи її зниження. Визначено фактори, що впливають на точність контролю.
Розроблено ЕМА товщиномір, розглянуті особливості побудови та питання схемотехніки його складових частин. Розглянуто алгоритми цифрової обробки прийнятого сигналу. Наведено опис виготовленого контрольного зразка для метрологічного забезпечення толщиномера.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.11.13 – Devices and methods of testing and materials structure determination. – National technical university "Kharkiv Politechnical Institute", Kharkiv, 2015. Thesis is devoted to solution of important theoretical and practical task to ensure ultrasound control of the metal products thickness by using electromagnetic-acoustical method in cases of dielectric coatings (gaps) with thickness up to 10 mm. Work includes analysis of existing acoustic methods and devices for thickness measurement, their main advantages and disadvantages are reviewed. Based on the results of analysis of the given disadvantages, the most advanced ways was set off - electromagnetic-acoustical (EMA) method. The problems of selection of the optimal signal agitate sonorous vibrations by EMA method were reviewed. Calculations of the taken energy are given for the analysis of the practicability to use variants of probing signal. Electric model of amplifier output stage of probing signal and sensor is reviewed, peculiarities of its operation are described. Results of researches and developments dedicated to increase thickness measurement quality and efficiency are given. Matters to build of the transmitting and receiving analog tracts are reviewed. The signal level dependence on voltage research on sensor's transmitting winding are conducted. Impact of a gap on the signal level was examined. Results of the dependence of dead spot length on a gap and methods to its reduction are given. Factors affecting accuracy of control are determined. EMA thickness gauge was designed. The main factors of design are examined. The digital processing algorithm of the received data was reviewed. Metrological characteristics of the developed device were made.
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McLaren, S. "High-resolution ultrasonic non-destructive testing." Thesis, City University London, 1987. http://openaccess.city.ac.uk/8335/.
Повний текст джерелаАнотація:
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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Warren, Laura. "Non destructive testing of drystone walls." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760966.
Повний текст джерелаАнотація:
Drystone structures have been widely used throughout the UK and other parts of the world for hundreds of years. Many of these structures are still in use today with many of the existing drystone structures within the UK being over 100 years old. Drystone construction techniques have formed over the years to make best use of stone properties, enabling these structures to resist the loadings upon them. Typical construction styles can often be attributed to certain types of stone, each with their own characteristics. Within these styles subtle variations can be found, often specific to an area, which work best with the properties of the local stone types. The predominant use of drystone structures also influences the way in which they are built in a particular area. This has been demonstrated in comparing the construction within the UK to that in the Cevennes area of France. The existing retaining wall stock needs to be assessed by the authorities that manage them. Many of these walls support highways and infrastructure, so adequate assessment and monitoring of these structures is vital to ensuring these services are maintained. Assessment of a structure mainly relies on engineering judgement, often with little to no prior knowledge of its behaviour or details of its construction. This thesis studies a wide number of walls both in the UK and France to understand qualitatively the construction of these structures, and how the material used together with local practise influences the overall construction. This in turn influences the ways in which loads are resisted by each of the main construction types. Following from this it goes on to look at practical ways in which assessment could be aided by identifying features within a wall that are known to assist or hinder a wall’s performance. The main technique developed for this is thermal imaging. Through practical studies and thermal modelling, a number of proposals have been put forward regarding the best times of day for using this technique. The type of features that may be identified has also been examined and discussed.
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Hedlund, Nadja. "Non-Destructive Testing Of Concrete Bridges." Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81923.
Повний текст джерелаАнотація:
Non-destructive testing is of great value in cases where a structure's future is investigated to find out what the best measure is. It is not always the best solution to demolish and build new. Many structures can be repaired and function several more years. In this thesis the main goal is to investigate some different non-destructive techniques and learn more about difficulties and strengths. The test subjects will be a cast T-beam in a laboratory environment as well as a case study of a railway bridge in Abisko. The different testing equipment being used in this thesis is a covermeter, a rebound hammer and ultrasonic pulse velocity. For both the T-beam and the bridge the results are overall very good. The covermeter is proven to be both easy to use and very reliable and the ultrasonic pulse velocity was more to learn about and more difficult but is giving very good results as well. Conclusions after the thesis project is that it requires a lot of experience of the user and time to make non-destructive testing useful and competitive in the society. Getting all the pieces together it is a powerful tool that hopefully is a sustainable asset in the future, regarding both economic and environmental issues.
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Weaver, Andrew Ronald. "Correlation of non-destructive pavement test devices." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0030/MQ65526.pdf.
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Höglund, Kristofer. "Non-destructive Testing Using Thermographic Image Processing." Thesis, Linköpings universitet, Datorseende, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-89862.
Повний текст джерелаАнотація:
In certain industries, quality testing is crucial, to make sure that the components being manufactured do not contain any defects. One method to detect these defects is to heat the specimen being inspected and then to study the cooling process using infrared thermography. The explorations of non-destructive testing using thermography is at an early stage and therefore the purpose of this thesis is to analyse some of the existing techniques and to propose improvements. A test specimen containing several different defects was designed specifically for this thesis. A flash lamp was used to heat the specimen and a high-speed infrared camera was used to study both the spatial and temporal features of the cooling process. An algorithm was implemented to detect anomalies and different parameter settings were evaluated. The results show that the proposed method is successful at finding the searched for defects, and also outperforms one of the old methods.
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Colla, Camilla. "Non-destructive testing of masonry arch bridges." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/12165.
Повний текст джерелаАнотація:
Stone masonry arch bridges form a critical part of the transportation system. Present methods of assessment are sometimes too conservative and a number of bridges fail the assessment even though they appear in good condition. Non-Destructive Testing can play a key role and three Non-Destructive techniques - radar, sonics and conductivity measurements- are proposed for bridge testing with the aim of obtaining structural dimensions, material characteristics and integrity information which would lead to a more accurate assessment of the structural conditions being made. After discussing problems and limitations with current analytical and load testing methods of assessment, a review of archetypal forms of bridge construction methods employed along the centuries ismade, showing that a greater variety of bridges than commonly believed, exists. The review also enables an Engineer to have some indication of construction type relating to the area, era and designer. The work then includes site work on two masonry bridges and laboratory experiments. On site, the three Non-Destructive Techniques mentioned were used for testing two Scottish stone masonry bridges (one with a brick arch ring) with the aim of obtaining information about the condition and nature of the materials in the fill, the internal configuration of the structure and the geometrical dimensions of the elements. Data from each technique were plotted in the form of cross-sectional tomographic maps and the results interpreted and compared. Limitations are also discussed. In the laboratory, experiments with radar were undertaken to calibrate the technique in controlled conditions and also, and more importantly, to obtain information about phenomena of signal behaviour and material properties as would be found in a masonry arch bridge. The findings served the purpose of aiding a better planning of radar surveys to be made and an improved understanding and interpretation of the radar data to be obtained.
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Kang, Bu Byoung. "Excitation method for thermosonic non-destructive testing." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/1411.
Повний текст джерелаАнотація:
Thermosonics is a non-destructive testing method in which cracks in an object are made visible through the local generation of heat caused by friction and/or stress concentration. The heat is generated through the dissipation of mechanical energy at the crack interfaces by vibration. The temperature rise around the area close to the crack is measured by a high-sensitivity infrared imaging camera whose field of view covers a large area. The method therefore covers a large area from a single excitation position so it can provide a rapid and convenient inspection technique for structures with complex geometry and small and closed cracks. An ultrasonic horn, originally designed for welding, has generally been used for thermosonic testing. However, it is diffcult to obtain reproducible and controllable excitation with the existing horn system because of non-linearity in the coupling; surface damage can also be produced by chattering caused by loss of contact between the tip of the horn and the structure. Therefore, the general aim of the study was to develop a reliable and convenient excitation method that should excite sufficient vibration for the detection of the defects of interest at all relevant positions in the structure and must also avoid surface damage. In this thesis, a numerical and experimental study for the development of the ex- citation method for reliable thermosonic testing is presented. Successful excitation methods for the detection of delaminations in composites and cracks in metal struc- tures are described. A simple, small wax-coupled PZT exciter is introduced as a con- venient, reliable thermosonic test system in applications where relatively low strain levels are required for damage detection such as composite plates. A reproducible vibration exciter may be su cient for thermosonic testing in some metal structures such as a thin plates. However, higher strain levels are often required in metal structures, though the required strain level is dependent on the crack size. This level of strain is not easily achieved within the reproducible vibration range because of non-linearity in the contact between the exciter and the structure. Therefore, studies are conducted with an acoustic horn with high power capability to investi- gate the characteristics of the vibration produced in a real structure with complex geometry and to develop a excitation method for achieving reliable excitation in the non-linear vibration range for thermosonic testing. An excitation method for a complicated metallic structure such as a turbine blade is also investigated and the in uence of the clamping method and the excitation signal that is input to the horn on the vibration characteristics generated in the testpiece is presented. As a result, a fast narrow band sweep test with a general purpose amplifier and stud coupling is proposed as an excitation method for thermosonic testing. This method can be ap- plied to different types of turbine blades and also to other components. One typical characteristic of a thermosonic test using non-linear vibration is the lack of repeata- bility in the amplitude and the frequency characteristic of the vibration. Therefore, vibration monitoring is necessary for reliable thermosonic testing and a Heating In- dex(HI) has been proposed as a criterion indicating whether su cient vibration is achieved in a tested structure or not. The HI is calculated from different vibration records measured by different sensors and these results are compared in this thesis. A microphone can provide a cheaper and more convenient non-contacting vibration monitoring device than a laser or strain gauge and the heating index calculated by a microphone signal shows similar characteristics to that calculated from the other sensors.
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Billson, Duncan Robert. "Advanced non-contacting ultrasonic techniques for non-destructive testing." Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/107577/.
Повний текст джерелаАнотація:
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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Schulze, Michael. "Non-destructive testing and evaluation of magnetostrictive materials." Thesis, University of Hull, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306801.
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Bates, Daniel J. "Rapid thermal non-destructive testing of aircraft components." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368859.
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Guyott, C. C. H. "The non-destructive testing of adhesively bonded structures." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/38341.
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Broberg, Patrik. "Towards automation of non-destructive testing of welds." Licentiate thesis, Luleå tekniska universitet, Strömningslära och experimentell mekanik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18447.
Повний текст джерелаАнотація:
All welding processes can give rise to defects that will weaken the joint and can lead to failure of the welded structure. Because of this, non-destructive testing (NDT) of welds have become increasingly important to ensure the structural integrity when the material becomes thinner and stronger and welds become smaller; all to reduce weight in order to save material and reduce emissions due to lighter constructions.Several NDT methods exists for testing welds and they all have their advantages and disadvantages when it comes to the types and sizes of defects that are detectable, but also in the ability to automate the method. Several methods were compared using common weld defects to determine which method or methods were best suited for automated NDT of welds. The methods compared were radiography, phased array ultrasound, eddy current, thermography and shearography. Phased array ultrasound was deemed most suitable for detecting the weld defects used in the comparison and for automation and was therefore chosen to be used in the continuation of this work. Thermography was shown to be useful for detecting surface defects; something not easily detected using ultrasound. A combination of these techniques will be able to find most weld defects of interest. Automation of NDT can be split into two separate areas; mechanisation of the testing and automation of the analysis, both presenting their own difficulties. The problem of mechanising the testing has been solved for simple geometries but for more general welds it will require a more advance system using an industrial robot or similar. Automation of the analysis of phased array ultrasound data consists of detection, sizing, positioning and classification of defects. There are several problems to solve before a completely automatic analysis can be made, including positioning of the data, improving signal quality, segmenting the images and classifying the defects. As a step on the way towards positioning of the data, and thereby easing the analysis, the phase of the signal was studied. It was shown that the phase can be used for finding corners in the image and will also improve the ability to position the corner as compared to using the amplitude of the signal. Further work will have to be done to improve the signal in order to reliably analyse the data automatically.Godkänd; 2011; 20111021 (andbra); LICENTIATSEMINARIUM Ämnesområde: Experimentell mekanik/Experimental Mechanics Examinator: Professor Mikael Sjödahl, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Teknologie doktor Torbjörn Löfqvist, Institutionen för system- och rymdteknik, Luleå tekniska universitet Tid: Måndag den 19 december 2011 kl 10.00 Plats: E246, Luleå tekniska universitet
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Golzan, Seyyed Behnam. "Simplified design method for energy dissipating devices in retrofitting of seismically isolated bridges." Thèse, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8948.
Повний текст джерелаАнотація:
Abstract: Highway bridges have great values in a country because in case of any natural disaster they may serve as lines to save people’s lives. Being vulnerable under significant seismic loads, different methods can be considered to design resistant highway bridges and rehabilitate the existing ones. In this study, base isolation has been considered as one efficient method in this regards which in some cases reduces significantly the seismic load effects on the structure. By reducing the ductility demand on the structure without a notable increase of strength, the structure is designed to remain elastic under seismic loads. The problem associated with the isolated bridges, especially with elastomeric bearings, can be their excessive displacements under service and seismic loads. This can defy the purpose of using elastomeric bearings for small to medium span typical bridges where expansion joints and clearances may result in significant increase of initial and maintenance cost. Thus, supplementing the structure with dampers with some stiffness can serve as a solution which in turn, however, may increase the structure base shear. The main objective of this thesis is to provide a simplified method for the evaluation of optimal parameters for dampers in isolated bridges. Firstly, performing a parametric study, some directions are given for the use of simple isolation devices such as elastomeric bearings to rehabilitate existing bridges with high importance. Parameters like geometry of the bridge, code provisions and the type of soil on which the structure is constructed have been introduced to a typical two span bridge. It is concluded that the stiffness of the substructure, soil type and special provisions in the code can determine the employment of base isolation for retrofitting of bridges. Secondly, based on the elastic response coefficient of isolated bridges, a simplified design method of dampers for seismically isolated regular highway bridges has been presented in this study. By setting objectives for reduction of displacement and base shear variation, the required stiffness and damping of a hysteretic damper can be determined. By modelling a typical two span bridge, numerical analyses have followed to verify the effectiveness of the method. The method has been used to identify equivalent linear parameters and subsequently, nonlinear parameters of hysteretic damper for various designated scenarios of displacement and base shear requirements. Comparison of the results of the nonlinear numerical model without damper and with damper has shown that the method is sufficiently accurate. Finally, an innovative and simple hysteretic steel damper was designed. Five specimens were fabricated from two steel grades and were tested accompanying a real scale elastomeric isolator in the structural laboratory of the Université de Sherbrooke. The test procedure was to characterize the specimens by cyclic displacement controlled tests and subsequently to test them by real-time dynamic substructuring (RTDS) method. The test results were then used to establish a numerical model of the system which went through nonlinear time history analyses under several earthquakes. The outcome of the experimental and numerical showed an acceptable conformity with the simplified method.Résumé: Les ponts routiers ont une grande valeur dans un pays parce qu’en cas de catastrophe naturelle, ils peuvent servir comme des lignes pour sauver des vies. Étant vulnérable sous des charges sismiques importantes, on peut considérer différentes méthodes pour concevoir des ponts routiers résistants et également pour réhabiliter des ponts existants. Dans cette étude, l'isolation de la base a été considérée comme une méthode efficace qui peut réduire significativement les effets des charges sismiques sur la structure. En réduisant la demande en ductilité sur la structure sans une augmentation notable de force, la structure est conçue pour rester élastique sous des charges sismiques. Le problème associé aux ponts isolés, particulièrement avec des appuis en élastomère, peut être leurs déplacements excessifs sous les charges de service et de séisme. Ceci peut défier l’objectif d'utiliser des appuis en élastomère pour les ponts typiques de petite portée où les joints de dilatation et les dégagements peuvent aboutir à une augmentation significative des frais d'exploitation et de maintenance. Ainsi, supplémenter la structure avec des amortisseurs d’une certaine rigidité peut servir de solution, ce qui peut cependant augmenter l’effort tranchant transmis à la sous-structure. Cette étude a pour but de fournir une méthode simplifiée afin d’évaluer les paramètres optimaux des amortisseurs dans les ponts isolés. Dans cette thèse, premièrement, basé sur une étude paramétrique, quelques directions sont données pour l'utilisation de dispositifs d'isolation simples, dont les appuis en élastomère, afin de réhabiliter des ponts existant avec une haute importance. Les paramètres comme la géométrie du pont, les clauses des normes et le type de sol sur lequel la structure est construite ont été appliqués sur un pont typique de deux portées. Il est conclu que les paramètres mentionnés peuvent déterminer l'emploi d'isolement de la base des ponts routiers. À la deuxième phase, basé sur le coefficient de réponse élastique des ponts isolés, une méthode de conception simplifiée d’amortisseur pour des ponts routiers réguliers isolés à la base a été présentée dans cette étude. En sélectionnant des objectifs pour la réduction du déplacement et la variation de l’effort tranchant, la rigidité et l'amortissement exigés d'un amortisseur hystérétique peuvent être déterminés. L’étude s’est poursuivie par une modélisation numérique d’un pont à deux portées pour vérifier l'efficacité de la méthode. Pour un modèle numérique d'un pont isolé typique, la méthode a été utilisée pour identifier des paramètres linéaires équivalents pour un certain déplacement et effort tranchant désigné. Par la suite, assumant un amortisseur de type hystérétique, les paramètres non linéaires de l’amortisseur ont été calculés et utilisés. La comparaison des résultats du modèle numérique sans amortisseur et avec l'amortisseur a démontré que la méthode proposée est suffisamment précise. Par la suite, un nouvel amortisseur hystérétique simple en acier a été conçu. Cinq spécimens ont été fabriqués de deux différents grades d’acier et ont été testés en combinaison avec un isolateur à l’échelle réelle dans le laboratoire de structures de l'Université de Sherbrooke. La procédure comprenait la caractérisation des spécimens par des tests cycliques en contrôle de déplacement et par la suite la réalisation d’essais par la méthode de sous-structuration dynamique en temps réel. Les résultats des essais ont été utilisés pour établir un modèle numérique du système qui a subi des analyses temporelles non linéaires sous plusieurs séismes. Le résultat des essais expérimentaux et numériques montrent une conformité acceptable avec la méthode simplifiée.
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Beriat, Pelin. "Non-destructive Testing Of Textured Foods By Machine Vision." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610405/index.pdf.
Повний текст джерелаАнотація:
In this thesis, two different approaches are used to extract the relevant features for classifying the aflatoxin contaminated and uncontaminated scaled chili pepper samples: Statistical approach and Local Discriminant Bases (LDB) approach. In the statistical approach, First Order Statistical (FOS) features and Gray Level Cooccurrence Matrix (GLCM) features are extracted. In the LDB approach, the original LDB algorithm is modified to perform 2D searches to extract the most discriminative features from the hyperspectral images by removing irrelevant features and/or combining the features that do not provide sufficient discriminative information on their own. The classification is performed by using Linear Discriminant Analysis (LDA) classifier. Hyperspectral images of scaled chili peppers purchased from various locations in Turkey are used in this study. Correct classification accuracy about 80% is obtained by using the extracted features.
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Nielsen, Brent Daniel. "Non-Destructive Soil Testing Using X-Ray Computed Tomography." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/nielsen/NielsenB1204.pdf.
Повний текст джерелаАнотація:
The mechanical behavior of soils is highly dependent on the particle microstructure. Traditional geotechnical engineering soil tests generally do not measure soil properties on a micro-scale; instead, macro scale properties are commonly used as estimates of microstructure properties in determining soil engineering behavior. Additionally, traditional geotechnical engineering soil tests are destructive in nature, and many test methods destroy the same soil properties they intend to measure. The goal of this research was to develop non-destructive soil test methods using x-ray computer-aided tomography (CT) scanning techniques to determine soil index properties. The CT scanning process provides a promising method for examining soil microstructure in a non-destructive manner. This research had two main objectives. The first was to configure the Montana State University Civil Engineering Department\'s computer-aided tomography scanner to perform CT scans on soil samples. The second objective was to use the CT scanner to develop nondestructive test procedures to determine geotechnical index properties of soils. Test methods were developed in this study to determine porosity, grain size distribution, and pore size distribution. The results from the first objective showed that the MSU CT scanning equipment is capable of producing high quality CT scans of soil materials. Resolution limitations of the scanner define the smallest soil grain size that is detectable in a CT scan, but the scan resolution may be improved by using smaller sample sizes for small particle soils. The results of the second portion of the study show that the non-destructive CT scanning test methods compare favorably with traditional geotechnical laboratory mechanical test methods. CT-measured porosity values and grain size distributions compared well with mechanical testing results, which were used to validate the new test methods. In addition, the CT-measured pore size distributions were in good agreement with an accepted pore size mathematical model. Since traditional pore size distribution tests are time-consuming, labor intensive, and destructive in nature, the non-destructive x-ray CT scanning test methods developed in this study show strong promise as a means for measuring an elusive soil property that cannot be accurately measured using traditional geotechnical testing procedures.
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Konadu, Sam Nyamekye. "Non-destructive testing and surface evaluation of electrical steels." Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/56107/.
Повний текст джерелаАнотація:
The ultimate objective of this project has been to develop a non destructive and surface evaluation on-line system for the determination of localised power loss in electrical steels Three different approaches were made by employing three different methods or measuring systems on steel samples to study sequentially: (1) the position of a grain boundary from both the front and the exact opposite side at the back of the grain-oriented electrical steel sample, (2) the position of grain boundaries at the surface of grain-oriented electrical steels through the measurement of the field distribution at the surface of the magnetised steel samples, and (3) the localised power loss in 3.25% grain-oriented electrical steels. In the first case, a computer based optical microscope and a 3-Chip colour video camera system was used to establish positions of grain boundaries in order to explain differences in field profiles outside the systematic accuracy of measurements In the second case a Magnetic (Atomic) Force Microscopy (MFM) system was used to raster scan the top surface of samples such as high permeability Grain oriented 3.25% Silicon Steel, Cobalt based nanocrystalline material and Nickel Iron alloy W597 Vacoperm 100, producing images for the establishment of grain boundaries. Grain boundaries of width between 50nm and 150nm were established. Thirdly, a three dimensional integrated Hall effect sensor has been used together with two pairs of needle probes to measure localised power loss in two dimensions P(x) and P(y) in a 3.25% silicon iron material, with the total localised power loss, P(t) being equal to the sum of the power loss in x-direction, P(x) and the power loss in y-direction P(y). The 3-D i.e. Hall effect sensor and the needles together in a single package were moved on an arm of Perspex material attached to an X-Y-Z precision position control system. A Lab View software package was used for the purpose of controlling the movement of the precision position control system as well as the data acquisition and processing. Colour images and contours, and also other graph representations showing variations in the intensity of power loss, strayed vertical magnetic field and flux density have been obtained. The overall mapped results showed a good correlation with predictions made from observed static domains. The correlation not only showed that loss varies from grain to grain, but it is non-uniform in the individual grains.
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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.
Повний текст джерела
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Hammarström, Elias. "Non-Destructive testing of concrete with ground penetrating radar." Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72621.
Повний текст джерелаАнотація:
Concrete structures are susceptible to deterioration over time and it is vital to continually assess concrete structures to maintain the structural integrity and prolong the service life. In recent years there has been an increased interest in non-destructive testing of concrete, i.e. assessing the state of the concrete without causing any damage to the structure in the process. There are many different techniques that falls under the term non-destructive testing and one of these that have gained prominence during the last few years is Georadar or ground penetrating radar, often shortened as GPR. GPR is a technique where microwaves are sent into the surface of the concrete by a device, the waves will reflect back to the device when encountering interfaces of areas with different electric properties. The waves are then received by the same device indicating the internal structure of the concrete. This makes the technique an excellent way to find reinforcement bars as the electric properties of concrete and metal strongly differ. In theory though, the technique should also be able to detect other internal differences in concrete, such as voids and corrosion areas but further research is still needed in these areas. This aim of this report is to evaluate ground penetrating radar as a non-destructive technique for assessment of concrete structures. In order to do this different tests has been conducted to evaluate the general performance and usability with a literature review introducing the science behind and what conclusions other researches has reached and using a testing methodology to reach the results. The tests can in a simple way be divided into two parts, first lab tests on a slab in a controlled setting where the internal structure was known, and then two shorter field trips in order to evaluate the performance properly insitu. The results were, to some extent, ambiguous. Although it was found that GPR is an excellent method for finding and locating near-surface reinforcement it was also concluded that the results could vary significantly depending on the location. In one of the field trips the performance of the GPR technique was compared to the performance of traditional cover meter and in this case the portability of the cover meter outperformed the somewhat clunky handling of the GPR. The concrete cover measurement using post-processing of the radar data gave a rough estimate, but once again evaluation still relied on the insitu conditions and the estimate were sometimes questionable. Finding reinforcement below the first layer yielded differing results and it was concluded that further tests were needed to fully evaluate the capabilities of the technique in this regard. The conclusions of the thesis was that although the tests show some potential for the method the results expected from GPR would strongly depend on suitability of the project and experience of the user. One important limiting factor was the availability of devices. For the current project only one specific device was used, it was theorized that another GPR device could get better results depending on the purpose. Furthermore, the lack of experience was also considered to be a limiting factor that might have had an effect on the results. For future research more tests on lower reinforcement and tests on detection of deterioration were suggested. Comparative studies with other similar non-destructive techniques were also considered to be an area of possible interest.
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Jian, J. "Ultrasound field measurement and modelling for non-destructive testing." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/17646/.
Повний текст джерелаАнотація:
Ultrasonic Testing (UT) is one of most important methods of Non-destructive Testing (NDT) and ultrasonic waves can be generated and detected by means of numeric methods. This thesis focuses on piezoelectric transducers and Electromagnetic Acoustical Transducer (EMAT). For testing with piezoelectric transducer (also called a probe), couplant has to be applied between the test material and the probe allowing for ultrasonic waves generated in the probe by an active piezoelectric crystal to propagate into the testing material. The couplant can be water, mineral oil, or gel, dependent on the applications concerned and material compatibility, for example, water for immersion tests or automatated inspections. No two piezoelectric transducer designs are identical in terms of their frequency range, beam propagation characteristics and directionality. The shape, dimensions, backing and matching of the transducer to the pulse generator together play a major role in the generation of the ultrasonic waves. Furthermore, the quantitative interpretation of pulse echo data obtained when such transducers are used in nondestructive evaluation (NDE) requires a complete knowledge of the ultrasonic field transmitted. Ultrasonic fields of circular probes have been studied experimentally using a miniature probe and theoretically with models developed to predict ultrasonic field of such a probe. Good agreement has been observed. In a fluid, the ultrasonic field generated by a circular piezoelectric transducer can be described in terms of a combination of locally plane waves that radiate in the geometric region straight ahead of the active transducer element and edge waves radiating from the rim of the element. When a piezoelectric transducer is directly mounted onto a solid material, the ultrasonic field includes locally plane longitudinal waves, edge longitudinal waves and mode-converted edge shear waves. Both cases can be studied using miniature piezoelectric probes. For electrically conductive materials, EMATs can be used for generation by means of Lorentz force or magnetostriction or both, and detection. EMAT technique is non-contact and couplant free and can work at high temperature. These attributes make it ideal for inspection in extreme conditions, such as high temperature, high speed, rough surface, etc. This thesis focuses on Lorentz force generation. The main disadvantages of an EMAT detector are its lower sensitivity compared to a piezoelectric probe and it is not straightforward to miniaturise the device to operate as a point sensor for the range of wavelengths of interest here. Therefore, optimal EMAT design is extremely important for successful EMAT application. Ultrasound may be generated without presence of external magnetic field as excitation electric current provides magnetic field as it induces eddy currents in the material under test, which creates Lorentz forces for ultrasonic generation. Where external magnetic field is applied, EMATs have to be designed correctly to achieve enhanced efficiency. As an example, Rayleigh wave EMAT generation has been studied. It is found that where external magnetic field is applied, constructive or destructive effects have been observed, which is understood dependent on direction of the external magnetic fields applied relevant to electric current direction. Optical interferometer to measure the true normal displacement of the solid surface with a resolution in the order of nanometres, but it is much more complex than an EMAT and a piezoelectric probe and requires an optically flat surface. The receiving EMAT detector measures particle velocity. By careful design, in-plane or out-of-plane (or both) velocities can be chosen for detection. This capability is very useful for the detection of longitudinal waves, shear waves, Rayleigh waves or Lamb waves efficiently. The ultrasonic pulse-echo technique has been widely used in ultrasonic NDT. Ultrasonic pulse-echo responses and ultrasonic field signals are not the same. Typically, edge waves are rarely seen in a pulse echo response because the plane waves that are normal to the major face of the active crystal of the same probe are nearly in phase to constructively result in a significant signal whilst edge waves arrive at the active crystal in different directions and different phases cancelling each other and destructively producing only a small signal that is barely observable. As an example of ultrasonic pulse-echo application, weak bond evaluation, has been performed. Weak bond evaluation has always been a challenge. As an example of practical applications, this study has evaluated Integrated Circuit packaging in electronic industry using scanning acoustical microscopy. The relationship among resulting ultrasonic C-scan images, destructive mechanical failure measurement, degradation cycles have been observed. The result is promising indicating the SAM is a very useful tool for weak bond evaluation. Ultrasonic field measurement using a miniature probe and specially design EMAT is very important to characterize and standardize a probe. Such a technique can also find its applications in defect detection and categorization, which has not been considered in this study.
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Hadadeh, Fawaz. "3D Probe for Magnetic Imaging and Non-destructive Testing." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS421/document.
Повний текст джерелаАнотація:
La thèse est dédiée au développement des sondes à base de capteurs magnétorésistifs capable de détecter les trois composantes du champ simultanément pour le contrôle non destructif par courants de Foucault et pour l’imagerie magnétique. Une première partie donne un aperçu de l’état de l’art des capteurs et des méthodes d’imagerie et du contrôle. Dans une seconde partie, la réalisation des sondes trois axes est donnée. Cela a inclus la micro fabrication, la réalisation de l’électronique de lecture, la conception et la réalisation de la partie mécanique et d’émission. Pour cela un travail important de simulation a été nécessaire. L’application de ces sondes sur des cas modèle pour l’imagerie magnétique avec une résolution submillimétrique est ensuite décrite. La sonde proposée dans cette thèse a été aussi utilisée avec succès pour détecter des défauts dans des échantillons d'aluminium et de titane avec un bon rapport signal sur bruitThe thesis is dedicated to the development of probes based on magnetoresistive sensors capable of detecting the three components of the field simultaneously for eddy current non-destructive testing and for magnetic imaging. A first part provides an overview of the state of the art of sensors, and imaging and control methods. In a second part, the realization of the three-axis probes is given. This included the micro-fabrication, the realization of the reading electronics, the design and realization of the mechanical part and emission. For this, an important simulation work was necessary. The application of these probes to model cases for magnetic imaging with submillimeter resolution is then described. The probe proposed in this thesis has also been used successfully to detect defects in aluminum and titanium samples with a good signal-to-noise ratio
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Sposito, Giuseppe. "Advances in Potential Drop Techniques for Non-Destructive Testing." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4373.
Повний текст джерелаАнотація:
In the field of Non-Destructive Testing, Potential Drop (PD) techniques have beenused for decades, especially in the petrochemical and power generation industries,for monitoring crack growth and wall thickness variations due to corrosion and/orerosion in pipes, pressure vessels and other structures. Inspection is carried out by injecting currents in the specimen to be tested andmeasuring the arising electrical potential di erence between two or more electrodesplaced on its surface. The presence of a defect generally increases the resistance andhence the measured voltage drop; inversion of these data can give information onthe size and shape of the defect. However, while the principle underlying these techniques is relatively simple, somedi culties have been encountered in their practical applications. Many commercialsystems based on PD methods, for instance, require the injection of very largecurrents in order to obtain su ciently large signals; doubts have been raised onthe stability of these methods to variations in the contact resistance between theelectrodes and the inspected material. The present work aims to show that someof these problems can be easily overcome, and to evaluate the capabilities of PDtechniques for crack sizing and corrosion mapping. After a brief review of the advantages, disadvantages and applications of the mainelectromagnetic methods for Non-Destructive Testing, an experimental setup forPotential Drop measurements which was developed for this work and which usessmall alternating currents (AC) is described. The setup is benchmarked against existingPD systems and then used to validate a model that allows AC PD simulationsto be run with a commercial Finite Element code. The results of both numericalsimulations and experimental measurements are used to investigate the possibilityof sizing defects of complex geometry by repeating the analysis at several di erentfrequencies over a broad range, and of reconstructing the depth pro le of surfacebreakingdefects without the need for assumptions on their shape. Subsequently, the accuracy to which it is possible to obtain maps of corrosion/erosion on the far surfaceof an inspected structure is discussed, and results obtained with an array probethat employs a novel arrangement of electrodes are presented. Finally, conclusionsare drawn and suggestions for further research are made.
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Lin, Xin-Yu. "Lossless image compression for aerospace non-destructive testing applications." Thesis, University of Central Lancashire, 2004. http://clok.uclan.ac.uk/18830/.
Повний текст джерелаАнотація:
This thesis studies areas of image compression and relevant image processmg techniques with the application to Non-destructive Testing (NDT) images of aircraft components. The research project includes investigation of current data compression techniques and design of efficient compression methods for NDT images. Literature review was done initially to investigate the fundamental principles of data compression and existing methods of lossless and lossy image compression techniques. Such investigation provides not only the theoretical background, but also the comparative benchmarks for the research project. Chapter 2 provides general knowledge of image compression. The basic predictive coding strategy is introduced at the beginning of chapter 3. Fundamental theories of the Integer Wavelet Transform (IWT) can be found in chapter 4. The research projects proposed mainly three innovative methods for lossless compression of NDT images. Namely, the region-based method that employs regionoriented adaptation; the texture-based method that employs a mixed model for the prediction of image regions with strong texture patterns; and a hybrid method that utilizes advantages from both predictive coding and IWT coding. The main philosophy of lossless image compression is to de-correlate the original image data as much as possible by mapping from spatial domain to spatial domain in the predictive coding strategy or from spatial domain to transform domain in the IWT coding strategy. The proposed region-based method aims to achieve the best mapping by adapting the de-correlation to the statistical properties of decomposed regions using the component's CAD model. With the aid of component CAD models to divide the NDT images of aircraft components into different regions based on the material structures, the design of the predictors and the choice of the IWT are optimised according to the specific image features contained in each region having the same material structure. The texture-based method achieves the best de-correlation by using a mixed data model in the region possessing strong texture patterns. A hybrid scheme for lossless compression of the NDT images of aircraft components is presented. The method combines the predictive coding and the IWT. After region-based predictive coding, the IWT is applied to the error images produced for each decomposed region to achieve further image de-correlation by preserving the information contained in the error images with fewer transform coefficients. The main advantages of using the IWT are its multi-resolution nature and lossless property with integer grey level values in images mapped to integer wavelet coefficients. The proposed methods are shown to offer a significantly higher compression ratio than other compression methods. The high compression efficiency is seen to be achieved by not only a combination of the predictive coding and the IWT, but also optimisation in the design of the predictor and the choice of the transform according to the specific image features contained in each region having similar material structures.
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von, Wowern Per. "Design of an encoder converter forautomated non-destructive testing." Thesis, KTH, Maskinkonstruktion (Inst.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226316.
Повний текст джерелаАнотація:
WesDyne Sweden AB is a Non-Destructive Testing (NDT) company specializedin the examination methods ultrasonic testing, eddy current testing and visualinspection. To verify an examination procedure before the actual inspection atsite, a test rig consisting of a three or four axes motion system is used. WesDyne saw a need to be able to modify the position signals from the position encoders in order to increase the exibility and in some case the accuracy when scanning objects with ultrasonic or eddy current probes. Thus, this thesis is regarding the design and evaluation of an encoder converter. The main task is to transform from Cartesian to polar coordinates and calculate the shortest distance between two points in space. Although, these calculations will introduce a delay. It is therefore of interest to look into how delays aect the NDT measurements.The selection of a microcontroller for the encoder converter was an importantpart of the thesis project. Initial tests were done with the Arduino Mega. Itwas concluded that more processing power was needed than the Arduino Mega could provide. The choice nally fell on the xCORE-200 eXplorerKIT fromXmos. The main tasks for the rmware developed for the xCORE-200 eXplorerKIT was to sample position signals, modify the signals and then output the modied signals. A printed circuit board was designed to act as an adapter card between the motorcontroller, measurement instrument and the xCORE- 200 eXplorerKIT. The encoder converter consisted of these two cards encased with supplementary components. A Windows graphical user interface application was developed to enable the change of settings of the encoder converter and overview of positions.Three tests with eddy current testing were done with a test block with emulated cracks in order to evaluate the performance of the encoder converter. The delay test showed that the Encoder converter had a maximal delay of 303 μs which corresponded to an average position error up to 0:12 mm. Two more tests with the test block were performed with the modied signals, polar coordinates and distance, from the encoder converter.The maximum average position error in these two test were 0:19 mm. The required accuracy depends on the circumstances but for most applications an error lower than 0:12 mm is acceptable. From the test results it can be concluded that conversion of position signals can improve accuracy in some cases of eddy current testing.WesDyne Sweden AB är ett företag inom oförstörande provning, med specalitet inom metoderna virvelström, ultraljud och visuell provning. För att verifiera proceduren inför en provning används testriggar med tre och fyra axligt rörelsesystem. WesDyne såg ett behov av att kunna modifiera positionssignalerna från positionsenkodrarna för att öka flexibiliteten och i vissa fall förbättra noggrannheten vid virvelström och ultrljudsprovning. Positionssignalerna används för att trigga mätningar med mätinstrumentet. Detta examensarbete handlar därav om utveckling och testning av en encoderomvandlare. Dess huvuduppgift var att kunna räkna ut polära koordinater och kortaste distans mellan två punkter i rymden. Beräkningarna kom att medföra en fördröjning av postionssignalen. Det fanns därav anledning att även undersöka hur olika fördröjningar påverkar mätresultat. En viktig del av exjobbet var valet av mikrodatorplattform för encoderomvandlaren. Först gjordes tester med Arduino Mega. Dock upptäcktes det att denna inte var kraftfull nog för uppgiften. Valet föll slutligen på xCORE-200 eXplorerKIT från Xmos vilket ansågs bäst kunna uppfylla kraven. Huvuduppgifterna som ingick i den firmware som utvecklades till xCORE-200 eXplorerKIT var att läsa in postionssignaler, göra om signalerna och sedan skicka ut dessa. Ett kretskort designades för att fungera som länk mellan motorstyrenheten, mätinstrumentet och xCORE-200 eXplorerKIT. Detta byggdes in i en låda med kompletterande komponenter för att kunna utföra tester med encoderomvandlaren. Ett grafisk gränsitt för windows utvecklades för att kunna se positioner och kunna ändra inställningar i enkoderomvandlaren. För att utvärdera enkoderomvandlaren gjordes tre olika typer av tester med virvelströmsprovning på testblock med emulerade sprickor. Fördröjningstestet visade att enkoderomvandlaren hade en maximal fördröjning av positionssignalen på 303 μs vilket gav ett genomsnittligt lokaliseringsfel av sprickorna på upp till 0:12 mm. Vid de två senare testerna då de modifierade positionsignalerna användes för att registrera virvelström mätningar, var det största genomsnittliga felet som uppmättes 0.19 mm. Nogrannheten som krävs varierar beroende på applikation men generellt är ett fel under 0.5mm godtagbart. Slutsatsen från testresultaten visar att omvandling av positionssignaler kan oka noggrannheten vid vissa fall av virvelströmsprovning.
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Ali, Balhassn S. M. "Development of non-destructive small specimen creep testing techniques." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14121/.
Повний текст джерелаАнотація:
Having knowledge of the current creep strength of service-aged components in high temperature installations such as nuclear power stations, oil refineries and chemical plants is essential for their safe and economic operation. Obtaining this knowledge may involve the use of small material samples. These small samples may be removed from weld regions or from component surfaces. Improving small specimens creep testing techniques, whereby a reliable uniaxial minimum strain rate and rupture data can be obtained, has been a major engineering concern for the last 20 years or so. This thesis includes the development of the small ring creep testing specimen in order to allow the ring specimen to be manufactured and tested with various shapes and geometries. The shape and size of the available small material samples normally dictates the ring shape, e.g., circular or elliptical. However, changing the ring shape leads to a change in the conversion factors, which are used to convert the ring data to the corresponding uniaxial data. Therefore, the effects of the ring geometry with different thicknesses, on the conversion factors, are described in this work. The finite element analyses have been used to assess the effects of shear deformation on the ring behaviour and also to determine the optimum ring ii geometry. Nickel base Superalloy 738 steel at 800oC and (Bar-257) P91 steel at 650oC have been used to validate the testing method. Two new small sized creep test specimens are also described in this thesis, i.e., (i) a small (Two-bar) specimen, which is suitable for use in obtaining the uniaxial MSR and creep rupture data and (ii) a small notched specimen which is suitable for obtaining the multiaxial stress state parameter. The specimen testing techniques, modeling, loading and manufacturing are described for both specimen types in this work. Finite element analyses have been used to assess the effects of the two-bar specimen (TBS) dimensions on the conversion factors, the failure time, the minimum strain rate, and to determine optimum dimension ratio ranges for the specimen. The two-bar specimen and the small notched specimen have been used to obtain a full set of material constants for two high temperature materials, i.e., (i) typical (as received) P91steel at 600oC and (ii) weak (Bar-257) P91 steel at 650oC. The results show remarkably good agreement between the data obtained from the two new small specimen testing techniques and the data obtained from corresponding uniaxial tests. The major advantages of the small ring specimen, the two-bar specimen and the small notched specimen testing techniques, over the existing small specimens testing techniques, are also included.
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Pierce, Robert S. "Signal enhancement of laser generated ultrasound for non-destructive testing." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/18395.
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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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Andersson, Angelica. "Combined speckle interferometry and speckle correlation for non-destructive testing." Licentiate thesis, Luleå tekniska universitet, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17020.
Повний текст джерелаАнотація:
When a sample is studied during loading in a tensile test machine, the sample is often exposed to rigid body motions during loading at the same time as it deforms due to tension. Therefore, the small deformation field is hard, or impossible, to measure when it is overlaid by a large motion. The large rigid body motions can be measured with methods like speckle correlation (also called digital speckle photography, DSP), but the results might be of too poor accuracy to resolve the deformation field. Interferometric methods on the other hand might measure the deformation field but the rigid body motion makes the fringes disappear. In this thesis a method is presented that makes it possible to master such measuring situations, by a combination of speckle correlation and speckle interferometry (also called TV holography, ESPI or DSPI). Both theory and experiments are presented. It is shown that speckle correlation can determine the speckle motion in the recording in order to determine the small deformation field in the interferometric algorithm. Speckle correlation can also be used to determine the amount of shear in shearography allowing a quantitative determination of the spatial derivative of the deformation field.Godkänd; 2000; 20070318 (ysko)
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Jama, Bandile, Jasson Gryzagoridis, and Graham Wilson. "Aspects of thermography for non-destructive testing in mechanical maintenance." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2579.
Повний текст джерелаАнотація:
Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.Infrared thermography (IRT) is a non-contacting, non-destructive testing (NDT) technique that provides relatively fast results from inspections; for example, in the detection of defects in engineering components and in systems' condition monitoring. This study examines the use and possible effectiveness of infrared thermography for the detection of faults and defects in just a few aspects that one encounters in the vast mechanical maintenance arena. The study discusses three aspects of infrared thermography, namely internal leaks inspections using passive infrared thermography, pulse thermography and induction thermography both active IRT NDT techniques for the detection of subsurface and surface defects. The promising results that were obtained by performing an experiment in the laboratory using a model fluid handling pipe network, with three isolation valves connected in parallel, encouraged performing inspections in an operating power plant, where it was suspected that there were leaks from safety and drain isolation valves. In both situations, the results were obtained in a short period of time and indicated that passive infrared thermography can detect internal leaks in pipe networks. Pulsed thermography is an active non-contacting non-destructive testing technique used to detect subsurface defects in monolithic materials and delamination's in composites. In the particular experiment that was performed pulse thermography was benchmarked with the conventional technique of ultrasound testing. PVC, stainless steel and mild steel specimens manufactured with flat bottom holes (as models of subsurface defects) were subjected to pulse thermography. The time duration to detect the presence of a defect represented by a temperature contrast or a hot spot on the specimen's surface was approximately a couple of seconds following the thermal excitation. No further characterization of the defect was possible with the technique. In contrast when using the ultrasound testing technique to test the specimens, it took considerable time to detect the defects, however, data in terms of size and depth beneath the surface became available thus enabling their full characterization.
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Watson, James Nicholas. "The application of neural networks to non-destructive testing techniques." Thesis, Edinburgh Napier University, 2001. http://researchrepository.napier.ac.uk/Output/9470.
Повний текст джерелаАнотація:
The low strain test method has become the prevalent method for integrity testing of cast in situ foundation piles. The automated interpretation of the sonic echo traces resulting from this test would prove beneficial to industry through the standardisation of the test method procedure and a reduction in the time spent analysing results. Therefore, in this research the generalisation and feature extraction strengths of artificial neural networks have been exploited to aid test trace interpretation. This study involved the identification of three multilayer networks considered most suitable for the heteroassociative function approximation task described above. Multilayer Perceptron (MLP) networks, Radial Basis Neural Networks (RBNN) and Wavelet Basis Neural Networks (WBNN) have all been trained using numerically generated data and their performances compared to identify the optimum network type. While each network presented similar strengths and weaknesses in fault diagnosis, statistical analysis suggested that the MLP network was marginally more successful in quantifying changes in cross-sections along the pile length. Field data from three test sites have confirmed that the network can identify, locate and quantify significant (±13%) changes in diameter along the pile length (within known test method limitations). The network has also diagnosed changes in diameter at the pile head. This task is notoriously difficult using conventional techniques and has been facilitated through the development of a novel pre-processing technique: the wavelet mobility scalogram.
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Alleyne, David N. "The non-destructive testing of plates using ultrasound Lamb waves." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/7312.
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Clark, Max. "Non-destructive and geotechnical testing of railway track bed ballast." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/13415.
Повний текст джерелаАнотація:
This thesis examines two techniques to identify the condition of rail track ballast: ground penetrating radar (GPR) and infra-red thermography. Basic work was undertaken on ballast durability using the slake durability test. Laboratory work using (GPR) was undertaken and the dielectric properties of rail track bed ballast were evaluated, using clean and spent ballast with various moisture contents. This was the first study of its kind. These results were examined and verified on a prototype track bed at The University of Edinburgh, where the conditions were known. This showed that GPR could be used to characterise the composition of in-situ railway track bed ballast. GPR was then used in a full-scale working track situation and different areas of clean and spent ballast successfully identified. Similar laboratory work was also undertaken using infrared thermography on samples of clean and spend ballast. It was found that clean and spent ballast changed temperature at different rates. Which agreed with theoretical models. The work undertaken on the prototype track bed and the full-scale working track confirmed these findings. Also the areas of clean and spent ballast identified with GPR were confirmed with infra-red thermography. This research has shown that GPR and infra-red thermography are appropriate techniques to obtain the characteristics of the composition of railway track bed ballast. Both techniques found the same anomaly on the full-scale working track: a patch of spent ballast within an area of clean ballast. These techniques are faster and more cost effective than current methods of ballast investigation.
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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.
Повний текст джерелаАнотація:
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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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.
Повний текст джерелаАнотація:
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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Cooper, J. A. "Laser-generated ultrasound with applications to non-destructive evaluation." Thesis, University of Hull, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375636.
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Eriksson, Jessica. "Penetrant and Magnetic Particle Testing with Blue Light : Non-destructive Testing with Fluorescent Media." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-28033.
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Ayra, Behnam. "Structural identification for condition assessment using modal non-destructive test data /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2000.
Знайти повний текст джерелаАнотація:
Thesis (Ph.D.)--Tufts University, 2000.Adviser: Masoud Sanayei. Submitted to the Dept. of Civil Engineering. Includes bibliographical references (leaves 152-159). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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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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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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Bourne, Simon James. "Novel hydrophilic polymer couplant for application in ultrasonic non destructive testing." Thesis, Cranfield University, 2001. http://hdl.handle.net/1826/4454.
Повний текст джерелаАнотація:
Ultrasonic Non Destructive Testing (NDT) is used to inspect materials and
structures for defects. Water is commonly used in NDT as a couplant to
improve ultrasonic transfer between an interrogating probe and test piece.
Unfortunately, the presence of water can cause corrosion and/or degradation
of the test piece material. The aim of this investigation was to evaluate
hydrated cross-linked hydrophilic polymers as candidate solid contact
ultrasonic couplant for use in the field of ultrasonic NDT.
The fact that hydrophilic polymers can absorb and retain large quantities of
water suggested that they might demonstrate the desirable ultrasonic
properties of water without the risks associated with conventional water
coupling. To test this, the ultrasonic properties of a range of hydrophilic
polymers were assessed. Excellent results were achieved, attenuation as low
as 0.36 and 0.71dB mm-1 at 5 and 1OMHz respectively being measured.
Great potential for efficient coupling was established due to acoustic
impedance in the region of 1.81VIN S M-3.
A polymer dependant coupling pressure of less that 1kg CM-2 was required to
achieve optimum coupling to a smooth steel block. Mechanical longevity,
evaluated by life testing, showed that polymers of up to 70% equilibrium water
content were best suited for dynamic testing applications. Temperature was
shown to effect ultrasonic properties; a drop from 5 to
-120C caused an
increase in attenuation of 3dB mm-1 and velocity of 350m s-1. Pressure
demonstrated no influence on attenuation but affected an increase in velocity
of 44m s-1 per kg CM-2
.
Further investigation into the unique ultrasonic
properties of hydrophilic polymers showed that the water sorption process
caused an increase in attenuation prior to saturation being reached. This was
attributed to the absorption of sound during the polymer transformation from
the glassy to rubbery condition observed during hydration. Dehydration from
100 to 37% saturation in a 60% equilibrium water content polymer caused an
increase in attenuation of 1.8dB mm-1 at 5MHz.
The research concluded with the design and development of a prototype
wheel probe employing hydrophilic polymer as the tyre. Operation at 5MHz in
pulse echo mode demonstrated results competitive to conventional immersion
testing. An MMA-VP cross-linked hydrophilic polymer of approximately 60%
equilibrium water content was found most suitable to this application.
This thesis suggests that there is a clear role for hydrophilic polymers in
ultrasonic NDT. The success of the wheel probe design developed as a result
of this research has resulted in patent application in both the UK and USA.
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Leach, John W. P. "Subsea inspection, non-destructive testing and cognitive dysfunction in commercial divers." Thesis, Lancaster University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329678.
Повний текст джерела
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Chen, Xiaoran. "Computational and Experimental Approach for Non-destructive Testing by Laser Shearography." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-theses/928.
Повний текст джерелаАнотація:
"Non-destructive testing (NDT) is critical to many precision industries because it can provide important information about the structural health of critical components and systems. In addition, NDT can also identify situations that could potentially lead to critical failures. Specifically, NDT by optical methods have become popular because of their non-contact and non-invasive nature. Shearography is a high-resolution optical NDT method for identification and characterization of structural defects in components and has gained wide acceptance over the last decade. Traditional workflow of NDT by shearography has been determined to be inefficient, due to the requirements of having experienced operators that must determine the most suitable loading methods to identify defects in samples under testing as well as to determine the best system arrangement for obtaining the maximum measuring sensitivity. To reduce the number of experiments that are required and to allow inspectors to perform NDT by laser shearography in a more efficient way, it is necessary to optimize the experimental workflow. The goal of the optimization would be an appropriate selection of all experimental variables including loading methods, boundary conditions, and system¡¯s sensitivities, in order to avoid repeating experiments several times in the processes of components characterization and health monitoring. To achieve this goal, a hybrid approach using shearographic fringe prediction with Finite Element Analysis (FEA) has been developed. In the FEA simulations, different loading conditions are applied to samples with defects, and in turn, the shearographic fringes are predicted. Fringe patterns corresponding to specific loading conditions that are capable of detecting defects are chosen and experimental tests are performed using those loading conditions. As a result, using this approach, inspectors could try different combinations of loading methods, and system¡¯s sensitivities to investigate and select appropriate experimental parameters to improve defect detection capabilities of the system by using low-cost computer simulations instead of lengthy and expensive experiments. In addition, to improve the identification of defects on the sample, camera calibration and image registration algorithms are used to project the detected defects on the sample itself to locate and visualize the position of defects during shearographic investigations. This hybrid approach is illustrated by performing NDT of a plate made of acrylic that has a partial hole at the center. Fringe prediction with finite element analysis are used to characterize the optimized experimental procedures and in turn, corresponding measurements are performed. A multimedia projector is employed to project the defects on the surface of the plate in order to visualize the location of the partial hole (defect). Furthermore, shearographic system is used for other applications including NDT of a composites plate and of a thin latex membrane. The procedures shows the effectiveness of the approach to perform NDT with shearography methods. "
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Zhang, Hong. "Radio frequency non-destructive testing and evaluation of defects under insulation." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2646.
Повний текст джерелаАнотація:
The use of insulation such as paint coatings has grown rapidly over the past decades. However, defects and corrosion under insulation (CUI) still present challenges for current non-destructive testing and evaluation (NDT&E) techniques. One of such challenges is the large lift-off introduced by thick insulation layer. Inaccessibility due to insulation leads corrosion and defects to be undetected, which can lead to catastrophic failure. Furthermore, lift-off effects due to the insulation layers reduce the sensitivities. The limitations of existing NDT&E techniques heighten the need for novel approaches to the characterisation of corrosion and defects under insulation. This research project is conducted in collaboration with International Paint®, and a radio frequency non-destructive evaluation for monitoring structural condition is proposed. High frequency (HF) passive RFID in conjunction with microwave NDT is proposed for monitoring and imaging under insulation. The small-size, battery-free and cost-efficient nature of RFID makes it attractive for long-term condition monitoring. To overcome the limitations of RFID-based sensing system such as effective monitoring area and lift-off tolerance, microwave NDT is proposed for the imaging of larger areas under thick insulation layers. Experimental studies are carried out in conjunction with specially designed mild steel sample sets to demonstrate the detection capabilities of the proposed systems. The contributions of this research can be summarised as follows. Corrosion detection using HF passive RFID-based sensing and microwave NDT is demonstrated in experimental feasibility studies considering variance in surface roughness, conductivity and permeability. The lift-off effects introduced by insulation layers are reduced by applying feature extraction with principal component analysis and non-negative matrix factorisation. The problem of thick insulation layers is overcome by employing a linear sweep frequency with PCA to improve the sensitivity and resolution of microwave NDT-based imaging. Finally, the merits of microwave NDT are identified for imaging defects under thick insulation in a realistic test scenario. In conclusion, HF passive RFID can be adapted for long term corrosion monitoring of steel under insulation, but sensing area and lift-off tolerance are limited. In contrast, the microwave NDT&E has shown greater potential and capability for monitoring corrosion and defects under insulation.
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Bale, Jefri Semuel. "The damage observation of composite using non destructive testing (NDT) method." Thesis, Paris 10, 2014. http://www.theses.fr/2015PA100067/document.
Повний текст джерелаАнотація:
L'objectif de ce travail de thèse est d'étudier le comportement de l'endommagement des matériaux composites sous chargement statique et fatigue par contrôle non destructif (C.N.D) thermographie et soutenu par émission acoustique et la tomographie (CT scan). Pour cela, ce unidirectionnels composite à fibres de verre (GFRP) et discontinue composite à fibres de carbone (DCFC) ont été utilisés comme les éprouvettes qui ont fourni par PSA peugeot citröen, France. Une série d'essais mécaniques a été réalisée pour déterminer le comportement de l'endommagement sous chargement statique et fatigue. Pendant tout des essais mécanique, la thermographie a été utilisé pour l'observation en temps réel pour suivre l'évolution des températures sur la surface de l'éprouvette et supporté par émission acoustique dans certaines conditions. Cette étude a utilisé une forme rectangulaire et se compose d'éprouvettes trouées et non trouées au centre de l'éprouvette. La vitesse de déplacement constante est appliquée pour observer l'effet sur le comportement de l'endommagement sous chargement de traction statique. Sous les essais de fatigue, le paramètre constant de la fréquence et de l'amplitude de stress a été étudiée pour chaque niveau de charge pour avoir les propriétés de fatigue et l'évolution de l'endommagement de l'éprouvette. La tomographie a été utilisée pour confirmer l'apparition de l'endommagement et l'etat du matériau après l'essai de fatigue. L'analyse des résultats de l'expérimentation et de l'observation NDT montré le bon accord entre les résultats mechnical et NDT thermographie avec prise en charge par l'observation de l'émission acoustique en détecter l'apparition et la propagation de l'endommagement de GFRP PRV et DCFC sous chargement de statique en traction. Les essais en fatigue montrent que la dissipation thermique est liée à l'évolution de l'endommagement et également thermographie et peut être utilisé avec succès pour déterminer la limite d'endurance (HCFS) et la courbe de Wöhler du matériau composite. Les résultats par CT scan ont mesurée avec succès les endommagements et l'état du matériau après essai de fatigue du matériau compositeThe aim of this study is to investigate the damage behaviour of composite material in static and fatigue condition with non destructive testing (NDT) thermography method and supported by acoustic emission and also computed tomography (CT) scan. Thermography and acoustic emission are used in real-time monitoring techniques during the test. On the other hand, NDT observation of tomography is used for a post-failure analysis. In order to achive this, continuous glass fiber composite (GFRP) and discontinuous carbon fiber composite (DCFC) have been used as the test specimens which supplied by PSA Company, France. A series of mechanical testing was carried out to determine the damage behaviour under static and fatigue loading. During all the mechanical testing, thermography was used in real-time observation to follow the temperature change on specimen surface and supported by acoustic emission in certain condition. This study used rectangular shape and consist of specimen with and without circular notches (hole) at the center. The constant displacement rate is applied to observe the effect on damage behaviour under tensile static loading. Under fatigue testing, the constant parameter of frequency and amplitude of stress was explored for each load level to have the fatigue properties and damage evolution of specimen. The tomography was used to confirm the appearance of damage and material condition after fatigue testing. The analysis from the experiment results and NDT observation shown the good agreement between mechnical results and NDT thermography with supported by acoustic emission observation in detect the appearance and propagation of damage for GFRP and DCFC under static loading. Fatigue testing shows that thermal dissipation is related to the damage evolution and also thermography and can be successfully used to determine high cycle fatigue strength (HCFS) and S-N curve of fiber composite material. From post failure analysis, CT scan analysis successfully measured and evaluated damage and material condition after fatigue test for fiber composite material. v
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Blaney, Sean. "Unmanned aerial vehicle-based non-destructive testing methods for concrete structures." Thesis, Elsevier; Cement and Concrete Composites, 2018. https://dspace.library.uvic.ca//handle/1828/9757.
Повний текст джерелаАнотація:
In this work, unmanned aerial vehicle-based non-destructive testing methods for concrete structures are evaluated and developed. There exists a need for improved infrastructure inspection techniques with increased expediency. Unmanned aerial vehicles (UAVs) are highly mobile and have shown promise towards achieving this directive, but more work is required to adapt traditional NDT methods to be UAV-compatible. To this end, concrete sounding techniques were evaluated with a quantitative acoustic frequency analysis procedure on a series of concrete slabs. One such method was adapted for use with a UAV and was used to detect subsurface voids in one of the concrete samples and offer a means of depth estimation. This work was complemented with experiments concerning UAV-based visual and infrared imaging techniques already in practice for UAV-based concrete inspection. Together, findings indicate the strengths and weaknesses of the NDTs tested and suggest further improvements for UAV-based NDTs and inspection strategies moving forward. Development of a novel sensor platform for UAV-based measurement, as well as results of an actual bridge inspection using infrared and optical methods demonstrate the present capabilities of the UAV-based instrumentation.Graduate
2019-07-03
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Iskandarani, M. Z. "Application of smart classification techniques to non-destructive testing of composites." Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/109581/.
Повний текст джерелаАнотація:
Composites manufactured for applications in the automotive industry were non-destructively tested to determine damage using the following techniques: (1) Low frequency tapping. (2) High frequency (C-Scan). (3) Visual imaging. (4) Low and high temperature pulse video thermography. Various levels of impact energy were applied to the following types of composites (I) RIM: Reaction injection moulded. (II) Woven Glass. (III) GMT: Glass mat thermoplastic. Some interesting results were obtained which could be explained through analytical and numerical modelling. These results were analyzed through developments of the following algorithms: (a) A novel approach to damage detection using wavelength variation and sequence grouping software. (b) Correlation of the various NDT techniques through one mathematical equation and software. (c) The introduction of the uniformity factor concept and software to account for variations among samples quality in relation to experimental results. (d) The development of smart classification system together with standard neural network algorithms for prediction and classification. The objectives of this research were all achieved.
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Adewale, Ibukun Dapo. "Multiple parameters based pulsed eddy current non-destructive testing and evaluation." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/2766.
Повний текст джерелаАнотація:
Eddy current sensing technique is widely used primarily because of its high tolerance to harsh environments, low cost, broad bandwidth and ease of automation. And its variant, pulsed eddy current offers richer information of target materials. However, accurate detection and characterisation of defects remains a major challenge in the petro-chemical industry using this technique which leads to spurious detection and false alarm. A number of parameters are contributory, amongst which is the inhomogeneity of the materials, coupling variation effect and relatively large lift-off effect due to coating layers. These sometimes concurrently affect the response signal. For instance, harsh and dynamic operating conditions cause variation in the electrical conductivity and magnetic permeability of materials. Also, there is the increased need to detect defects and simultaneously measure the coating layer. In practice therefore, multi-sensing modalities are employed for a comprehensive assessment which is often capital intensive. In contrast to this, multiple parameter delineation and estimation from a single transient response which is cost-effective becomes essential. The research concludes that multiple parameter delineation helps in mitigating the effect of a parameter of interest to improve the accuracy of the PEC technique for defect detection and characterisation on the one hand and for multi-parameter estimation on the other. This research, partly funded by the Petroleum Technology Development Fund (PTDF), proposes use of a novel multiple parameter based pulsed eddy current NDT technique to address the challenges posed by these factors. Numerical modelling and experimental approaches were employed. The study used a 3D finite element model to understand, predict and delineate the effect of varying EM properties of test materials on PEC response; which was experimentally validated. Also, experimental studies have been carried out to demonstrate the capabilities of the proposed to estimate multiple parameters vis-à-vis defect depth (invariant of lift-off effects) and lift-off. The major contributions of the research can be summarised thus: (1) numerical simulation to understand and separate the effect of material magnetic permeability and electrical conductivity in pulsed eddy current measurements and experimental validation; (2) proposed the lift-off point of intersection (LOI) feature for defect estimation invariant of lift-off effects for ferromagnetic and non-ferromagnetic samples; a feature which is hitherto not apparent in ferromagnetic materials (a primary material used in the oil and gas industry); (3) separation and estimation of defect and the lift-off effects in magnetic sensor based pulsed eddy current response; and (4) application of the LOI feature and demonstration of increased defect sensitivity of the PEC technique with the proposed feature in both ferrous and non-ferrous conductive materials.
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Smith, Ian Colin. "Vision based systems for hardness testing and NDT." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317273.
Повний текст джерелаАнотація:
The work presented in this thesis concerns the development of vision based systems for two hardness (destructive) tests, namely; the Shore and Vickers and a quality assurance non-destructive test. In each case the vision system is based on an IBM PC compatible computer fitted with a commercially available frame store. Bespoke image analysis software was written using the C language for each system. In the Shore test, hardness is judged by the maximum rebound height attained by an indenter incident on a test sample. The purpose of the vision system is to measure the rebound height automatically. Laser light is used to illuminate the indenter and a vidicon vision camera is used to view its motion. Two approaches to the problem are considered; one in which image data is analysed in real time and one in which image·data is merely stored in real time and analysed a posteriori. Non-real time analysis is shown to be superior to real time analysis in terms of accuracy and reliablity and its software implementation is discussed in detail. The Vickers test uses the size of the permanent impression left by an indenter forced into the test material under a known load as a hardness index. In this case the purpose of the vision system is to measure the size of the indentation automatically. The original image analysis algorithms are shown to be capable of analysing good quality samples but are unreliable when applied to poor quality specimens. Further, fault-tolerant, algorithms are described to provide reliable and accurate results over wide variations in sample quality.The quality assurance application involves automated visual inspection of novel ferrite components for defects. Each component is approximately 8 mm in diameter, annular in shape, and coated with aluminium. Laser light is used to illuminate individual components which arc viewed using a charge-coupled device (CCD) video camera. Image analysis algorithms for characterising defects in component geometry and surface finish arc discussed. The system is shown to capable of measuring component edge eccentricity and hole offset as well as providing a quantitative description of surface chips and cracks. The system is further shown to be capable of separately classifying surface defects extending to the edge of a component. Calculation of shape parameters for surface defects also provides a means of distinguishing cracks from surface chips.