Orientador: Auteliano Antunes dos Santos Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-21T01:45:00Z (GMT). No. of bitstreams: 1 Vaz_BrunoFilipe_M.pdf: 3622447 bytes, checksum: 4729491ba809efa80fade4767a7247b1 (MD5) Previous issue date: 2012 / Resumo: Bielas falham quando submetidas a esforços que ultrapassam seu limite de escoamento. Esses elementos são projetados para suportar tanto esforços em tração quanto em compressão, embora os últimos sejam mais intensos. Para a criação de novas bielas, engenheiros fazem uso de análises de elementos finitos para validar seus desenhos, mas mesmo assim os desenhos atuais dessas peças seguem os modelos desenvolvidos décadas atrás. A validação das análises computacionais dos modelos é feita através de ensaios destrutivos ou medições e análises do produto em uso regular. Engenheiros de desenvolvimento e de testes seriam muito beneficiados por uma ferramenta de ensaios não destrutivos que possibilitassem validar resultados obtidos numericamente rapidamente e a um custo menor que os ensaios tradicionais. A obtenção de campos de tensão pode ser feita através de diversos métodos, dentre os quais se destaca como o mais amplamente utilizado o uso de strain-gauges. Este trabalho avalia o uso do método de medição de tensões em bielas por interferência de padrões de spekle, também conhecido como Eletronic Speckle Pattern Interferometry (ESPI). As tensões medidas na região plana da alma da biela são comparadas com resultados de elementos finitos. Essa região corresponde à porção interior da alma, excluindo-se as regiões de borda que possuem uma espessura maior. Baseando-se nos conceitos de delineamento de experimentos - DoE (Design of Experiments), foi feito um planejamento dos experimentos com a finalidade de encontrar uma configuração de medições que elimine, ou ao menos minimize a influência de fatores incontroláveis (ruídos). Os ensaios foram realizados em uma biela forjada submetida a esforços compressivos. Concluindo o trabalho foi mostrado que os campos de tensão obtidos pela técnica ESPI estavam em acordo com os resultados obtidos pelo método de elementos finitos, ressaltando assim a utilidade e os benefícios da aplicação da técnica no desenvolvimento de novos produtos que visam um aumento da segurança em componentes de motores / Abstract: Conrods fail when submitted to stresses higher than its yield limit. They are designed to support both compressive and tractive forces, although the first is usually more intense. Engineers use Finite Element simulations to create new shapes, but the main design still follows the one developed several decades ago. The validation of the results is usually performed through destructive tests or field evaluation. Test Engineers and Designers would benefit of a non-destructive tool that would expedite the validation and cost much less than conventional tests. Several possible methods to obtain the stress field of a part might be used, among which the best known and widespread is the use of strain gauges. In this work we evaluate the application of Electronic Speckle Pattern Interferometry (ESPI) to measure stresses in conrods in substitution to the classical techniques. The measurements are performed in the flat surface of the conrod and the results compared with those from Finite Elements simulations. This region corresponds to the inner portion of the rod body, excluding only the edges of it that are slightly thicker. An experimental design was developed, based mainly on the concepts of Design of Experiments - DOE, to eliminate or at least reduce the influence of the uncontrollable factors (noise) over the results. The tests were performed with a conventional forged connecting rod submitted to compressive efforts. In conclusion, we showed that the measurements of the stress and strain fields obtained by the ESPI technique are in accordance with the simulations and that this technique is a very useful tool for design engineers, improving the safety and reducing the development cycle in engine applications / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

This work studies guided wave propagation in pipes coated with thick highly viscoelastic coating materials. The main motivation for this study is the problems associated with Long Range Ultrasonic Testing (LRUT) of coated pipelines. The results reported in the literature show that the proper determination of the optimum LRUT parameters depends strongly on the bulk acoustic properties of the coating materials. The bulk acoustic properties of coating materials reported in the literature show that they could vary significantly depending on the coating material age, temperature and bonding level. The methods for acoustic characterisation of coating materials reported by other researchers, have been studied and it was found that they do not take into account the temperature changes and bonding level variation. In this work, the bulk acoustic properties of two highly viscoelastic bitumen based coating materials are investigated. The conventional methods for acoustic characterisation are studied and a new method for independent measurement of bulk shear properties of bitumen is developed. The bulk acoustic properties of bitumen based coating materials are also studied by two new characterisation methods. The first method derives the bulk coating material properties from experimental data on guided wave reflection coefficients. The second method derives the coating material bulk properties from experimentally measured guided wave attenuation data. It is demonstrated that these new methods deliver much more accurate values for the bulk acoustic properties when compared to the data measured by conventional methods. The second method is used to study the temperature effect on the bulk acoustic properties and it is demonstrated that temperature has a significant effect. The validity of the acoustic properties for the two bitumen materials is investigated through comparison between numerical predictions and experimental data measured for guided wave reflection coefficients and attenuation of the torsional T(0,1) and longitudinal L(0,2) guided wave modes. Good agreement is achieved in the frequency range between 20 kHz and 100 kHz, which is typical for LRUT of pipes.

Les voies ferrées n'ont cessé d'évoluer depuis l'apparition du premier rail en fer laminé (1789). Les traverses en bois laissent maintenant place à des traverses en béton alors que dans certains pays et dans les tunnels, le ballast est remplacé par des dalles continues en béton armé ou non. Ce type de voie nécessite cependant l'intégration de systèmes supports de rails permettant d'assurer le confort des passagers. Le système "low vibration track" développé par la société Sonneville fait partie de ce type de système. Il se compose d'un blochet en béton reposant sur une semelle micro-cellulaire le tout étant intégré dans un "chausson" en caoutchouc noyé dans la dalle en béton non armé. Ce système équipe aujourd'hui un peu plus de 1100 km de voies de par le monde dont les voies du tunnel sous la Manche, tunnel ayant la section sous-marine la plus longue du monde.Ce travail rentre dans le cadre de la chaire de recherche commune à l'Ecole des Ponts ParisTech et au groupe Eurotunnel et s'intéresse, d'une part à l'étude du comportement dynamique et, d'autre part à la dégradation de la voie ferroviaire du tunnel sous la Manche.La première partie de ce travail présente les modèles existants appliqués aux voies ballastées et propose de développer des modèles pour les voies non ballastées. En utilisant une condition périodique en régime stationnaire, on démontre que la distribution des efforts sur les systèmes supports est gouvernée par une relation caractéristique qui ne dépend pas du comportement des supports. Ce résultat permet de proposer un "système équivalent" de la voie représenté par un ressort caractérisé par sa rigidité et une pré-force qui ne dépendent que des caractéristiques du rail et du chargement. Ce modèle analytique permet alors de calculer rapidement la réponse dynamique de la voie quel que soit le comportement des supports (linéaires ou non linéaires), ce modèle ayant été validé par confrontation avec les résultats des mesures réalisées en tunnel. Ce modèle a enfin été développé pour une voie dont les supports présentent des propriétés mécaniques différentes (supports sains ou endommagés) et a été implanté dans un logiciel (logiciel "EuroAnalyse") qui permet de calculer la réponse dynamique de la voie en intégrant l'évolution des caractéristiques mécaniques de la voie.La deuxième partie est consacrée à l'étude de l'endommagement des blochets en béton du système support. La première phase de cette étude porte sur la compréhension de ces endommagements à l'aide d'une modélisation éléments finis 3D du blochet, la seconde étant consacrée à la mise au point d'une méthode d'identification de ces endommagements en tunnel. Pour ce faire, ce travail met expérimentalement en évidence l'existence d'une variation des deux premières fréquences propres et du coefficient d'amortissement des blochets en fonction de leur état de dégradation. Les mesures sur blochet montrent en effet qu’il existe une corrélation entre l'état de dégradation des blochets et leur signature vibratoire, ces mesures étant en accord avec les calculs éléments finis effectués. La méthode de mesure des fréquences propres basée sur l'analyse modale a été implantée dans un logiciel (logiciel "EuroDetection") qui fera partie intégrante du système automatique de détection des endommagements des blochets en tunnel que la société Eurotunnel utilisera dans le cadre de ses campagnes de maintenance de la voie / Railways have been evolving since the onset of the first rail rolled iron (1789). Wooden sleepers now give way to concrete sleepers while in some countries and commonly in tunnels ballast is replaced by continuous concrete slabs. This type of track, however, requires the integration of rail supports systems to ensure passenger comfort. The "low vibration track" (LVT) system developed by the company Sonneville is such a system. It contains a concrete block based on a micro-cellular pad all integrated in a rubber boot embedded in the slab of unreinforced concrete. This system today covers more than 1100km of railway track around the world, including the Channel tunnel.This work takes place within the framework of joint research between Ecole des Ponts ParisTech and the Eurotunnel group, that investigates the railway dynamic behavior and the support system degradation in the Channel tunnel.The first part of this work presents existing models for ballasted tracks and proposes extended models for non-ballasted tracks. Using a periodic condition of the railway track in steady state it can be shown that the distribution of loads on the support systems is governed by a characteristic relation that does not depend on the support behavior. This result allows us to offer an equivalent system represented by a preloaded spring. This analytical model is then used to calculate the dynamic response of the track by combining with support behavior (linear or nonlinear). This model has been validated by comparison with measurement data in the Channel tunnel. Lastly, a model is presented for a track whose supports have different properties. This model allows rapid calculation of track leveling due to support damage and has been integrated into the new software "EuroAnalyse".The second part of this work deals with the degradation of the LVT concrete block. Firstly, the research focuses on the damage mechanism by calculating the block stress with the help of the finite element method. The result shows that the concrete experiences tension stresses which can lead to damage by fatigue loads. Secondly, a method of identification is developed to monitor the concrete blocks in a tunnel. We show that the eigen frequencies of the block depend on its damage level and this is demonstrated by data and simulations. The method of measuring the eigen frequencies based on modal analysis has been integrated into the software "EuroDetection" which will be part of the track monitoring system for Eurotunnel

Abstract This Thesis proposes and describes the use of optical coherence tomography (OCT) as a non-contact and non-destructive characterization technique for printed electronics. It is based on and includes the first published results of such an application of the OCT technique. Several different types of structures were studied to evaluate the feasibility of the application. The measurement data was used to define the surface topography, physical dimensions of the specimen features, and to evaluate the ability to characterize multi-layered and multi-material structures. Presented OCT measurements were done for: screen-printed conductive and insulating structures, microfluidic channels, microscopy glass and organic field effect transistors (OFET), both coated with polymer, and inkjet-printed colour filters. A novel approach to encapsulation inspection was presented. The results show that OCT could be used for full volumetric and non-destructive characterization of the 1-to-2-µm-thin protective layers used in organic and printed electronics. The measurements presented in the Thesis were done using OCT devices in time and in spectral domains. Despite the focus on studying the application of the technique, as a result of observations and limitations of the existing equipment, a new type of OCT device has been developed. A high data acquisition rate of the spectrometer-based systems (SD-OCT) was combined with a broadband supercontinuum light source, used so far mainly in the time-domain (TD-OCT), to enable the sub-micron-resolution spectral domain optical coherence tomography (SMR SD-OCT). The supercontinuum generation effects with virtually white probing light and enables not only superior resolution, but also, e.g., true-colour OCT imaging. The measurements performed on the inkjet-printed colour filters confirm that despite the absorptive properties of the materials, characterization of the few-microns-thin ink layers is possible using visible range of the electromagnetic spectrum and spectral domain OCT. The study shows the potential and versatility of OCT in the printed electronics characterization. In addition, the Thesis discusses further development of the technique, needed to fully match the challenging requirements of the on-line quality inspection. / Tiivistelmä Väitöstyössä sovelletaan optista koherenssitomografiaa (OCT) painetun elektroniikan kontaktittomaan ja kohdetta rikkomattomaan karakterisointiin. Väitöstyö pohjautuu tuloksiin, joissa OCT-tekniikkaa on hyödynnetty ensimmäistä kertaa painettavan elektroniikan rakenteen karakterisoinnissa. Tekniikan soveltuvuutta tutkittiin mittaamalla useita erilaisia näytteitä. Mitattua dataa käytettiin pinnan topografian ja näytteen dimensioiden määritykseen. Lisäksi tutkittiin tekniikan soveltuvuutta monikerrosrakenteiden ja useista eri materiaaleista koostuvien näytteiden mittaukseen. OCT-mittaukset tehtiin seuraaville näytteille; silkkipainetuille johteille ja eristeille, mikrokanaville, polymeerillä päällystetyille mikroskooppilaseille ja orgaanisista aineista valmistettu kanavatransistoreille (OFET) sekä mustesuihkutulostimella valmistetuille värisuodattimille. Orgaaniset materiaalit ja painettava elektroniikka suojataan yleensä koteloinnilla. Tässä väitöstyössä esitellään uusi menetelmä koteloinnin tarkastukseen. Tulokset osoittavat, että OCT-tekniikkaa voidaan hyödyntää 1-2 mikrometrin paksuisen eristekerroksen volumetrisen rakenteen karakterisointiin kohdetta rikkomatta. Tässä väitöstyössä tehdyt mittaukset tehtiin aika- ja spektritason OCT-laitteilla. Huolimatta siitä, että väitöskirjatutkimus keskittyi tekniikan uusiin sovelluksiin, väitöstyössä havaittiin käytettävissä olevien laitteiden puutteellisuudet, jonka vuoksi myös uusi OCT-laite kehitettiin. Spektrometriin pohjautuvan OCT-systeemin (SD-OCT) nopeus yhdistettiin laajakaistaisen supercontinuum valonlähteen kanssa, jota on käytetty aikaisemmin käytännössä vain aikatason OCT-laitteissa (TD-OCT). Laajakaistainen valonlähde mahdollistaa jopa alle mikrometrin syvyyssuuntaisen resoluution. Supercontinuum valonlähde tuottaa käytännöllisesti katsoen valkoista valoa, joka mahdollistaa sekä erinomaisen tarkkuuden, että objektin luonnollisen värin mittaamisen. Mittaustulokset värisuodattimilla osoittavat, että vaikka suodattimissa käytetyt materiaalit absorpoivat spektritason OCT:ssa hyödynnettyä näkyvän aallonpituusalueen spektriä, tekniikalla on mahdollista mitata muutamien mikrojen paksuisia värisuodatinkalvoja. Väitöstutkimus osoittaa OCT-tekniikan monipuolisuuden ja mahdollisuudet painettavan elektroniikan karakterisoinnissa. Lisäksi väitöstyö käsittelee tekniikan jatkokehitystä, jotta se voisi vastata mahdollisimman hyvin reaaliaikaisen laadunvalvonnan tarpeisiin.

Dans le cadre du contrôle non destructif de matériaux, les scanners à rayons X sont devenus un moyen d’assurer la validité et la qualité de pièces de productions industrielles. TomoAdour, un prestataire de services privé en digitalisation 3D et tomographie industrielle à rayons X, utilise des technologies d’acquisition basées sur ce rayonnement telles qu’un scanner médical ou tomographe industriel, de manière à observer et à analyser des produits de ses clients. La nature des objets acquis (principalement de forte densité et de grandes dimensions) fait apparaître des défauts sur les images issues de ces scanners X. Il devient dès lors difficile, voire impossible, d’analyser les images produites. On notera en particulier la présence d’artefact métallique. Ce dernier est dû à la présence de matériaux très denses dans l’objet acquis et est la conséquence de la forte atténuation des rayons dans le métal et/ou de leur distorsion dans toutes les directions. Les données reconstruites sont donc souvent difficiles à interpréter directement, car ces artefacts peuvent masquer des informations importantes. De nombreuses méthodes ont été développées durant ces dernières années et la problématique de la réduction de l’artefact métallique a largement pu être étudiée, apportant bon nombre de solutions. Pourtant, les algorithmes proposés ne s’intéressent qu’aux applications médicales et ne tiennent donc pas compte des limitations physiques propres aux échantillons industriels. De plus, les méthodes proposées basent, toutes, leur traitement sur des données brutes, c’est-à-dire des données issues du scanner avant la phase de reconstruction (ensemble de radiographies ou de projections). Dans notre cas, seules les données reconstruites (tomogrammes, i.e. volume représentant l’objet) sont disponibles et il n’existe, à l’heure actuelle, aucune approche de réduction de l’artefact métallique basée sur ces reconstructions. Le but de ces travaux de recherche est donc de proposer, dans un premier temps, un outil permettant d’identifier et de quantifier l’artefact métallique dans les données reconstruites pour la correction de ces dernières. Dans un second temps, notre travail propose un ensemble d’approches adaptées à l’analyse de matériaux dans un contexte industriel [1; 2]. / In the field of non-destructive testing of materials, computed tomography became a good way to check defects in industrial piece production. TomoAdour is a private compagny specialized in 3D digitization and x-ray computed tomography, it uses medical and industrial imaging techniques to analyze materials provided by his customers. However, tomographic analysis is difficult to achieve due to the presence of high density objects (such that metal) in most produced pieces, leading to the well-known metal artifacts in reconstructed data. In X-Ray tomography, metal artifact is characterized by a local and straight hyper-signal. This observed phenomenon is due to high attenuations of the rays in the high density materials. Many different approaches have been proposed for metal artifact reduction during the last decade. However, these methods have been developed for medical application and does not take into account physical limitations specific to industrial materials. Moreover, state-of-the-art approaches start their process from the original projection data, that is to say directly from the acquired data. In our context, only reconstructed image is available due to clinical scanner usage, and there is currently no metal artifact reduction method only based on these data. The goal of this work is first to propose a tool which permit identifying and measuring metal artifact in the reconstructed data in order to correct them. Then, our work take in interest in presenting methods developed for an industrial context[1; 2].

The resin anchored rock bolt is used extensively in the mining industry to stabilize the roof and prevent it from collapsing. However, there are different defects associated with a resin anchored rock bolt. Examples are partially encapsulated bolts, over-spinned bolts and corroded bolts. These defects reduce the integrity of the roof, and thereby have an effect on the safety and productivity of the mines. The integrity of the rock bolts is a critical issue for the mining industry because of its influence on the safety of mining operations. Different research groups around the world have addressed the problem of determining rock bolt integrity. The most promising technique found in the literature study was based on guided ultrasonic waves (Beard and Lowe, 2003). This study extended the previous work by Beard and Lowe (2003) using guided ultrasonic waves, to investigate damage in more realistic embedded bolts which deviate from pure cylinders. The fundamental L(0,1) mode in its lower frequency range, as suggested by Beard and Lowe was utilized. This was done through the use of finite element model simulations of various defect scenarios, which were compared to experimental measurements on bolts. Defects like loss of resin encapsulation, voids and local corrosion cracks were addressed. The time traces of the different finite element defect scenarios could be directly compared to experimental time traces which distinguish this study from the analytical approach. Some finite element modelling issues were investigated and it was found that the time step is critical if an implicit solver is used, whereas for an explicit solver the element size is critical if accurate answers are needed. Furthermore it was also apparent that the boundary of the mortar has an influence on the results. The method used in the study was to move the boundaries far enough to prevent interference. This however increases the model size and thereby the computer resources required. Axisymmetric defects were modelled using axisymmetric finite elements to reduce the problem size. These models gave results comparable to the measured bolts. Three-dimensional finite element models seemed to be promising for simulating non-axisymmetric defects. It was found that it is not possible to solve large three-dimensional models without energy absorbing boundaries. Axisymmetrical and three dimensional finite element models of a partially encapsulated bolt and a bolt with a local corrosion crack were built. It was possible to detect simulated local corrosion cracks with the finite element models. Clear reflections for the crack in the bolt could be seen. If the bolt, resin and rock are cracked, different reflections will be detected. These different reflections complicated the interpretation of the results. Once the integrity of models such as these has been established, the models could in principle be used to train neural networks for use in commercial equipment. The present study was limited to lower frequencies because of computer resource limitations. Basic principles and modelling issues could however be addressed and it may be expected that these principles could soon be extended to higher frequencies with a new generation of computers. / Dissertation (MEng)--University of Pretoria, 2009. / Mechanical and Aeronautical Engineering / unrestricted

No description available.

Pneumatic drives are an integral part of many machinery, with high demands on their reliability. Unfortunately, they sometimes fail, either due to improper production or assembly at the factory or by gradual degradation of moving parts and sealing elements during operation. Current diagnostic methods do not allow localization or identification of the type of damage and do not allow the operator to make a qualified decision. This work deals with the use of acoustic emission for these purposes. On PB type cylinders manufactured by Poličské strojírny a.s., a methodology is introduced which leads to the direct identification or at least localization of selected defects. By implementing this methodology in the final inspection of the production plant, the percentage of exposed pieces of waste will be increased, thus preventing accidents of these faulty pieces during operation.

Bc. Veronika Turková Improvement of nonconformities control system Master´s thesis, Institute of metrology and quality assurance, Brno University of technology This thesis deals with the issue of improving the management system of nonconformities control in a company ALSTOM Power, s.r.o. ALSTOM Group, the Division of boilers production, located in Brno. This thesis contains an analysis of current status of nonconformities control process and designs a new nonconformity control process using a new internal database for resolving of nonconformities. These measures should deal with the efficiency of the management of nonconformities process and reduce current company pains.

The presented innovative magnetic testing method utilises the fact, that each commercially available electromagnet can not only be used as an actuator, but also comprises internal sensor functions. This allows a huge application variety in the fields of non-destructive testing and condition monitoring of electromagnetic systems during production and within the application in the field.