A systematic and detailed design, building and testing of a high-sensitivity real-time magnetovision imaging system for non-destructive testing (NDT) was the purpose of the research presented here. The magnetic imaging systems developed were all based on an ultra-high sensitivity Quantum Well Hall Effect (QWHE) sensors, denoted as the P2A, which is based on GaAs-InGaAs-AlGaAs 2DEG heterostructures. The research progressed from 0D (single sensor) to 1D (linear array) to 2D (two dimensional arrays) testing modalities. Firstly, the measurement of thermal and shot noises, drift, detection limit, and dynamic offset cancellation of the QWHE sensor were studied in detail to set the framework and limitations of the fundamental QWHE sensors before their eventual use in the imaging systems developed subsequently. The results indicate that the measured data agrees well with calculations for thermal and shot noise when the input bias current is < 3 mA. The measured drift voltages of various QWHE sensors (P2A and P3A) are less than 200 µV when the sensor bias voltage is less than or equal to 2 V. A 4-direction dynamic offset cancellation technique was developed and the results show that the offset equivalent magnetic field of the QWHE sensors can be reduced from ~ 1mT to readings equal to the Earth magnetic field (~ 50 µT). Secondly, a flexible 16 × 1 array and a 32 × 2 staggered array magnetic-field scanners were designed, built, and tested. The QWHE magnetometer had a field strength resolution of 100 nT, and a measurement dynamic range of 138 dB. The flexible 16 × 1 magnetic field scanner can be used to test uneven and/or curved surfaces. This gives the flexible magnetic field scanner better inspection capabilities in both welding hump and circular pipe samples. By the staggered arrangement of two sensor arrays, a 15.4 point per inch horizontal spatial resolution can be achieved for the staggered 32 × 2 magnetic field scanner. Both direct and alternating magnetic flux leakage (DC and AC MFL) tests with the QWHE magnetometer were accomplished to obtain graphical 2-dimensional magnetic field distributions. Both the shape and the location of defects can be identified. The results show that the sensor has high sensitivity and linearity in a wide frequency range which makes it an optimum choice for AC-MFL testing and both ferromagnetic and non-ferromagnetic materials can be investigated. Thirdly, real-time 8 × 8 and 16  16 QWHE array magnetic-field cameras were designed, built, and tested. These prototypes can measure static magnetic field strengths in a 2-dimensional plane. Different shapes of magnets and magnetic field polarities can all be identified by the 8 × 8 magnetic field camera. The camera has a resolution of 3.05 mT, and a dynamic range of 66 dB (the minimum and maximum fields measurable are 3.05 mT and 6.25 mT) and a real time magnetic field measurement rate of 13 frames per second (FPS). By contrast the1616 array magnetic field camera has an improved sampling rate of 600 frame per second and with the use of an interpolation technique, a spatial resolution of 40.6 point per inch can be achieved. The minimum and maximum detectable magnetic field for this magnetic field camera are 1.8 µT and 29.5 mT respectively leading to a record dynamic range of 84 dB for high quality imaging. Finally, a novel, hand held, magnetovision system based on the real-time 16 × 16 QWHE array magnetic-field camera was developed for improved DC and AC electromagnetic NDT testing. The system uses a new super heterodyne technique for data acquisition using the QWHE sensor as a multiplier. This is the first report of such a technique in Hall effect magnetometry. The experimental results of five case studies demonstrate that the defects location and shape can be successfully measured with MFL in DC and AC magnetic field configurations including depth profiling. The major advantages of this real-time magnetic-field camera are: (1) its ease to use as a MFL testing equipment in both DC and AC NDT testing, (2) its ability to provide 2D graphical images similar to Magnetic Particle Inspection (MPI) but without its inherent health and safety drawbacks, (3) its capability to test both ferromagnetic and non-ferromagnetic materials for deep defects below the surface using low frequency alternating magnetic fields, and (4) its ability to identify materials (metals) by alternating external magnetic field illuminations, which has considerable potential in several applications such as security checking and labelling, magnetic markers for analysis, bio-imaging detection, and medical treatments amongst others.

Electromagnetic acoustic transducers (EMATs) are increasingly used in industries due to their attractive features of being non-contact, cost-effective and the fact that a variety of wave modes can be generated, etc. There are two major EMATs coupling mechanisms: the Lorentz force mechanism for conductive materials and the magnetostriction mechanism for ferromagnetic materials; EMATs operated on Lorentz force mechanism are the focus of this study. This work aims to investigate novel efficient modelling techniques for EMATs, in order to gain further knowledge and understanding of EMATs wave pattern, how design parameters affect its wave pattern and based on above propose and optimise novel sensor structures. In this study, two novel modelling methods were proposed: one is the method combining the analytical method for EM simulation and the finite-difference time-domain (FDTD) method for US simulation for studying the Rayleigh waves' properties on the vertical plane of the material; the other one is the method utilizing a wholly analytical model to explore the directivity of surface waves. Both simulations models have been validated experimentally. The wholly analytical model generates the radiation pattern of surface waves, which lays a solid foundation for the optimum design of such sensors. The beam directivity of surface waves was investigated experimentally, and results showed the length of wires has a significant effect on the beam directivity of Rayleigh waves. A novel configuration of EMATs, variable-length meander-line-coil (VLMLC), was proposed and designed. The beam directivity of surface waves generated by such novel EMATs were analytically investigated. Experiments were conducted to validate such novel EMATs models, and results indicated that such EMATs are capable of supressing side lobes, and therefore resulting in a more concentrated surface waves in the desired direction. Further, another two novel configuration of EMATs, the four-directional meander-line-coil (FDMLC) and the six-directional meander-line-coil (SDMLC), were proposed and designed; results showed these EMATs are capable of generating Rayleigh waves in multiple directions and at the same time suppressing side lobes.

abstract: Micromachining has seen application growth in a variety of industries requiring a miniaturization of the machining process. Machining at the micro level generates different cutter/workpiece interactions, generating more localized temperature spikes in the part/sample, as suggested by multiple studies. Temper-etch inspection is a non-destructive test used to identify `grind burns' or localized over-heating in steel components. This research investigated the application of temper-etch inspection to micromachined steel. The tests were performed on AISI 4340 steel samples. Finding, indications of localized over-heating was the primary focus of the experiment. In addition, change in condition between the original and post-machining hardness in the machined slot bottom was investigated. The results revealed that, under the conditions of the experiment, no indications of localized over-heating were present. However, there was a change in hardness at the bottom of the machined slot compared to the rest of the sample. Further research is needed to test the applicability of temper-etch inspection to micromilled steel and to identify the source of the change in hardness. / Dissertation/Thesis / M.S.Tech Technology 2010

Orientador: Aparecido Carlos Gonçalves / Resumo: Os problemas associados às falhas protéticas e cirurgias de revisão aumentaram muito desde que a substituição total da articulação passou a ser aplicada também a pacientes mais jovens e mais ativos, portanto, a necessidade de resolver ou reduzir os problemas relacionados ao desgaste é de suma importância. Partindo-se dessa premissa, decidiu-se por projetar, fabricar e validar uma máquina de ensaio de desgaste do tipo acoplamento orbital, capaz de realizar o ensaio de desgaste de Prótese Total de Quadril (PTQ), obedecendo aos parâmetros de carga e movimento (Flexão/Extensão, Adução/Abdução), estabelecidos pela Norma ABNT NBR ISO 14242-3. Após a validação, foi realizado o ensaio de uma amostra composta de uma cabeça femoral de 28 mm de diâmetro de aço inox ASTM F138 e acetábulo de polietileno convencional (UHMWPE). O ensaio teve a duração de um milhão de ciclos (aproximadamente 12 dias), equivalente a aproximadamente um ano de uso da prótese in vivo e teve duas avaliações de perda de massa e volume ao longo do ensaio. Os resultados obtidos da taxa média de perda de massa e volume por milhão de ciclos, foram compatíveis com os resultados apresentados por outros autores. A avaliação do desgaste sofrido pelo componente acetabular (análise visual e microscópica) e a análise morfológica das partículas geradas pelo desgaste via MEV, forneceram informações importantes para melhor interpretar os mecanismos de desgastes (abrasão, adesão e fadiga) ocorridos durante o ensaio tribológico. ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The problems associated with prosthetic failure and revision surgery have increased greatly since total joint replacement has also been applied to younger and more active patients, so the need to resolve or reduce wear-related problems is of paramount importance. Based on this premise, it was decided to design, manufacture and validate a wear test machine of the orbital coupling type, capable of performing the Total Hip Prosthesis (PTQ) wear test, according to load and movement parameters ( Flexion / Extension, Adduction / Abduction), established by the Standard ABNT NBR ISO 14242-3. After validation, a sample composed of a 28 mm diameter femoral head of ASTM F138 stainless steel and conventional polyethylene acetabulum (UHMWPE) was performed. The assay lasted for one million cycles (approximately 12 days), equivalent to approximately one year of use of the prosthesis in vivo and had two mass and volume loss evaluations throughout the trial. The results obtained from the average loss rate of mass and volume per million cycles were compatible with the results presented by other authors. The evaluation of the wear of the acetabular component (visual and microscopic analysis) and the morphological analysis of the particles generated by the MEV wear, provided important information to better interpret the mechanisms of wear (abrasion, adhesion and fatigue) that occurred during the tribological test. It is a fact that these wear mechanisms compromise the useful life of a hip joint ... (Complete abstract click electronic access below) / Doutor

Grain nitrogen (N) concentration is a major quality criterion of malting barley for which there is a narrow range that producers must meet to satisfy market requirements (1.52 – 1.84 %). In recent years growers in Ireland have had difficulty producing grain with a high enough N concentration to meet these requirements using standard recommended agronomic regimes. The reasons for the lower than expected grain N concentrations are not known. There is interest from growers and maltsters in the development of a system to forecast likely grain N concentration from crop measurements made at or before flowering. A forecasting system would allow growers to identify crops at risk of falling below specification and to apply late N fertiliser if needed. It would also enable maltsters to plan grain intake and malting operations in advance of harvest. The aim of this project was to investigate the potential for predicting grain N concentrations of spring barley from crop and soil measurements made at ear emergence. The main objectives were to 1) investigate the relationships between measurements made at ear emergence and grain N concentration at harvest in order to identify which characteristics should be included as variables in multiple regression models to explain variation in grain N concentration, 2) to use the models with independent data sets to predict grain N concentration and test the accuracy of the predictions, 3) to quantify the recovery by the crop of fertiliser N applied at anthesis and its effects on grain N concentration and 4) to determine whether non-destructive techniques can provide estimates of crop growth and N content for use in the prediction models. Field experiments were established with plots of spring barley (Hordeum vulgare cv. SY Taberna) at one site in 2013 and two sites in 2014 representative of those employed in malting barley production in Ireland. Fertiliser N applications were varied over the range 0 – 210 kg N/ha (with dressings split between sowing and mid-tillering) to provide a range of crop growth and grain N concentrations. In some experiments additional applications of N were made at anthesis to quantify effects on grain N concentration and seed rate treatments (150, 300 and 600 seeds per m-2) imposed to test the accuracy of predictions of grain N concentration in crops of varying canopy structure. Destructive samples were taken to determine total crop N content and canopy N distribution at ear emergence and harvest. Measurements of soil mineral N availability, ear numbers per m-2 and the number of spikelets per ear were made at ear emergence. Final grain yield and quality were also determined at harvest. Grain N concentration is the quotient of grain N content and grain yield. Both grain N content and yield explained a significant amount of the variation in grain N concentration observed across sites and fertiliser N treatments indicating that estimates of both must be included in models to predict N concentration. Grain N content was strongly related to total crop N content at harvest (P < 0.001; R2 = 0.96), which in turn was related to canopy N content at ear emergence (P < 0.001; R2 = 0.94). Similarly, grain yield was strongly related to total crop biomass at harvest (P < 0.001; R2 = 0.83), which in turn was related to crop biomass at ear emergence (P < 0.001; R2 = 0.88). These results indicated that predictions of grain N concentration might be possible from measurements of crop N content and biomass at ear emergence and that the effects of variation in harvest index, nitrogen harvest index and post-anthesis N uptake on grain N concentration are likely to be negligible under normal agronomic conditions in Ireland. Weather conditions in 2013 were unusually dry and estimates of soil moisture deficit and available water capacity indicated that the crop was water stressed. In 2014 weather conditions were close to the long term averages for the sites. Multiple regression models using canopy N content and biomass at ear emergence as explanatory variables accounted for 91% of the variation in grain N concentration when data from 2014 were used and 80% when data from both 2013 and 2014 were combined. The models developed using data from plots sown at 300 seed per m-2 in 2014 were tested against independent data from plots sown at 150 seeds per m-2 in the same year and at the same sites to test the accuracy of predictions across plant populations and canopy structures. The models were also tested using data from experimental plots and commercial fields collected in 2015 to test the accuracy of predictions in a different year across a range of sites and varieties. Values of grain N concentration predicted from measurements at ear emergence were compared with actual grain N concentrations measured at harvest. The accuracy of predictions was good with an R2 of 0.80 and RMSE of 0.114 %N for the test across seed rates and R2 of 0.80 and RMSE 0.220 %N for the validation in 2015 across sites and varieties. In 2014, grain N concentrations were increased significantly by applications of additional N fertiliser at anthesis with apparent recoveries (increase in N content (kg) /kg fertiliser N applied) in grain averaging 50% over the range of application rates indicating scope for increasing grain N concentration in crops predicted to be at risk of not meeting malting specifications Non-destructive measurements displayed significant relationships with N content and biomass at GS 59 across a combination of sites and seasons. However, issues in performance relating to instrument saturation were obvious and estimates never produced more accurate predictions of grain N concentration than destructive sampling. The results show that grain N concentration of spring barley can be predicted with good accuracy from measurements of canopy N and crop biomass made at ear emergence when the weather conditions are comparable to the long term average for the region. As conditions of drought are rare in Ireland, the prediction models are a potentially valuable tool to aid crop management and post-harvest operations by growers and maltsters. Further testing will be needed before users can be confident in the reliability of predictions over years and a larger set of varieties.

Este trabalho apresenta os resultados da aplicação da metodologia de inspeção não intrusiva (INI) em equipamentos do sistema de dessulfurização de gás numa plataforma petrolífera, com o auxílio da inspeção baseada em risco utilizando a norma API RP 581. A inspeção não intrusiva é aplicada tendo como fundamentos as guias de inspeção, como a DNV-RP-G103, que reúne informações de como executar e justificar o seu uso, a fim de garantir a segurança das instalações, eliminando a necessidade de uma parada do equipamento para a realização da inspeção. Contudo nem todos os equipamentos puderam ser inspecionados por esta metodologia, devido a limitações operacionais e/ou construtivas. O trabalho conclui que a inspeção não intrusiva pode ser aplicada à inspeção de equipamentos sem prejuízo ao mapa de risco do equipamento ou da unidade, e naqueles onde não é possível à utilização somente da metodologia, a mesma poderá ser aplicada em conjunto com a inspeção convencional fornecendo informações importantes sobre o estado do equipamento, melhorando assim a confiabilidade do planejamento da parada de manutenção e uma redução dos custos envolvidos. / This paper presents the results of applying the methodology of non-intrusive inspection (INI) in electrical system flue gas desulphurization an oil rig, with the help of riskbased inspection using the API RP 581. The non-intrusive inspection is implemented with the guides as the foundations of inspection, such as DNV-RP-G103, which gathers information on how to make and justify its use, to ensure the safety of installations, eliminating the need for a parade equipment to perform the inspection. However not all equipment could be inspected by this method, due to operational limitations and / or constructive. The paper concludes that the non-intrusive inspection can be applied to inspection of equipment subject to the risk map of the equipment or unit, and those where it is not possible to use only the methodology, it may be applied along with conventional inspection providing important information on the status of the equipment, thereby improving the reliability of planning maintenance shutdown and lower costs.

Delamination and cracks within the multilayer structure are typical failure modes observed in microelectronic and micro electro mechanical system (MEMS) devices and packages. As destructive detection methods consume large numbers of devices during reliability tests, non-destructive techniques (NDT) are critical for measuring the size and position of internal defects throughout such tests. There are several established NDT methods; however, some of them have significant disadvantages for detecting defects within multilayer structures such as those found in MEMS devices. This thesis presents research into the application of transient infrared thermography as a non-destructive method for detecting and measuring internal defects, such as delamination and cracks, in the multilayer structure of MEMS devices. This technique works through the use of an infrared imaging system to map the changing temperature distribution over the surface of a target object following a sudden change in the boundary conditions, such as the application of a heat source to an external surface. It has previously been utilised in various applications, such as damage assessment in aerospace composites and verification of printed circuit board solder joint manufacture, but little research of its applicability to MEMS structures has previously been reported. In this work, the thermal behaviour of a multilayer structure containing defects was first numerically analysed. A multilayer structure was then successfully modelled using COMSOL finite element analysis (FEA) software with pulse heating on the bottom surface and observing the resulting time varying temperature distribution on the top. The optimum detecting conditions such as the pulse heating energy, pulse duration and heating method were determined and applied in the simulation. The influences of thermal properties of materials, physical dimensions of film, substrate and defect and other factors that will influence the surface temperature gradients were analytically evaluated. Furthermore, a functional relationship between the defect size and the resulting surface temperature was obtained to improve the accuracy of estimating the physical dimensions and location of the internal defect in detection. Corresponding experiments on specimens containing artificially created defects in macro-scale revealed the ability of the thermographic method to detect the internal defect. The precision of the established model was confirmed by contrasting the experimental results and numerical simulations.

Circular air-coupled ultrasonic testing (ACUT) setup for the inspection of commercial carbon-carbon composite aircraft brake disks was developed in Intelligent Measurement and Evaluation Laboratory (IMEL) at Southern Illinois University Carbondale (SIUC). The developed test setup utilizes Airstar single channel air-coupled equipment and has only manual A-scan and B-scan capability. The developed ACUT technique is unique compared to the commercial C-scan ultrasonic systems and is proficient, fast, economically feasible, and easy to implement method particularly for the inspection of carbon-carbon (C/C) composites aircraft brake disks. Prior to conducting air-coupled measurements, wobble analysis was carried out. This was important because significant wobbling in the test setup can lead to the interference of the reflected and the incident beam which would result to inaccurate ultrasonic measurements. The measured deviation due to wobbling, surface profile of the disk, design, and experimental error were relatively small. Therefore, these errors were neglected while performing ACUT measurements. For ACUT measurements, several through-transmitted amplitude signals were recorded within the C/C brake disks manually. The images were then reconstructed using Matlab based on the through-transmitted amplitude signals. Finally, a comparison was drawn between the reconstructed images and the C-scan images of the C/C brake disks obtained from the commercial Airstar C-scan ACUT system. Like commercial C-scan ACUT image results, reconstructed images were also able to detect all defects in the commercial C/C brake disks which served for the system verification and validation. In addition, defect, non-defect, and suspected areas within the C/C brake disks were quantified with air-coupled measurement. For this, light microscopy was conducted for every sample made from each C/C brake disks at lower magnification of 10X. It was concluded that it is very difficult to assess the crack or delamination situation based on a 2D micrograph of one depth. Also, it was concluded that an internal porosity and micro-cracks may not be only factors that can be related to defects. Finally, an intelligent systems approach, specifically, fuzzy logic and artificial neural network (ANN) methodologies were implemented for the automatic defect detection in commercial C/C aircraft brake disks by using air-coupled ultrasonic results. For this, a multi-layer perceptron (MLP) with two hidden layers and a scaled conjugate gradient back-propagation (BP) learning algorithm was used for the ANN training. The network training process was performed in an off-line mode using the ANN toolbox in Matlab. The network training was repeated until a steady state was reached, where there was no further change in the synaptic weights. The ANN provided plausible results in detecting the defect areas for different C/C brake disks. It was also demonstrated that the system was able to learn the rules without knowing any algorithm for automatic defect detection.

Sistemas de ensaios não destrutivos por ondas guiadas despertam cada vez mais a atenção tanto da indústria, como da academia. Isso deve-se, principalmente, às possibilidades que as ondas guiadas permitem, como maior área de triagem que o ultrassom convencional. Porém a técnica tem suas limitações, já que esta apenas gera uma estimativa da localização de um defeito e não a sua dimensão. Nessa limitação, algoritmos tomográficos apresentam uma possibilidade de avanço da técnica, pois permitem determinar não só a localização de corrosões e defeitos, mas também seu dimensionamento. Este trabalho apresenta tomografia de difração como uma alternativa para avaliação de integridade estrutural. Primeiramente, utilizou-se análise por métodos numéricos para mostrar a validade dos algoritmos e posteriormente foi realizado um experimento em uma chapa real com o objetivo de reconstruir a imagem do defeito. / Guided waves nondestructive testing systems are increasingly attracting industrial and academic attention. The mainly reason for this attention is the possibility of screening a large area than conventional ultrasound technique. However, Guided Waves Testing has limitations, since it gives only an estimation of the location of a defect, but not the dimensions. Tomographic algorithms come up with an improvement of the technique, because it allows discovery not only the location of corrosions and defects, but the dimensions too. This work brings Diffraction Tomography as an alternative to structural health monitoring. First, a numerical analysis was implemented to demonstrate the validity of the algorithms, after that an experiment in a real plate was made with the objective to recover the defect image.

A operação segura e eficiente em unidades de produção de petróleo e gás depende do desempenho de seus dispositivos, componentes e estruturas. Dutos rígidos são importantes componentes utilizados na indústria offshore, comumente empregados como flowlines e risers. Durante a vida em serviço destes componentes, eles sofrem tensões axiais cíclicas associadas a sua movimentação, ao processo de extração de petróleo e ao vórtice das marés. O aço inoxidável superduplex surgiu na última década como um material alternativo para ambientes quimicamente agressivos, mas quando catodicamente protegidos contra a corrosão, esses aços são vulneráveis a fragilização por hidrogênio. Este trabalho tem como objetivo, através da técnica de Ensaio Não Destrutivo de ultrassom phased array, monitorar o crescimento de defeitos internos e externos criados intencionalmente próximos à raiz e ao reforço da solda de um tubo de aço superduplex (UNS S32750) de 6´´ submetido a fadiga tração-tração e fragilização induzida por hidrogênio devido à proteção catódica. As inspeções foram realizadas periodicamente com varreduras de 30 a 75° ao longo da circunferência da solda, por um transdutor linear 1-D de 16 elementos e 5MHz acoplado a uma sapata de 36°. Os resultados obtidos foram utilizados para alimentar análises de integridade estrutural, obtenção da curva da/dN x ΔK. / Safe and efficient operation in oil and gas production units depends on the performance of your devices, components and structures. Rigid pipelines are important components in the offshore industry, common used as flowlines and risers. During a life in service of components, they suffer cyclical axial stresses associated with their movement, by the oil extraction process and tidal vortex. Super duplex stainless steel has emerged in the last decade as an alternative material for chemically aggressive environments, but when cathodically protected against corrosion, it is vulnerable to hydrogen embrittlement. This work aims to, through the ultrasonic non-destructive testing by phased array monitor the growth of internal and external defects created intentionally close to the root and reinforcement of the weld of a superduplex steel tube (UNS S32750) with diameter of 6" submitted to tensile-traction fatigue and hydrogen-induced embrittlement due to cathodic protection. The inspections were performed periodically with 30 to 75° scans along the circumference of the weld, by a linear transducer of 1-D, 16-element and 5MHz coupled to a wedge of 36°. The obtained results were used to feed structural integrity analyzes, obtaining the curve of da/dN x ΔK.