Dans une démarche de « Virtual Testing » au sein du projet européen MAAXIMUS, cettethèse se focalise sur l’étude de fixations aveugles aéronautiques au sein d’assemblages composites.Par le biais d’une étude expérimentale et numérique, le comportement mécaniquede plusieurs références de fixations est étudié sous différentes sollicitations (traction statiqueet fatigue, simple cisaillement, pull-through). Les principaux facteurs influents sontainsi dégagés. L’installation d’un type de fixation pris comme référence est correctementreproduite en simulation grâce à l’utilisation de lois matériau élastoplastiques et de critèresd’endommagement. Le comportement hors-plan de stratifiés est modélisé en faisant appelà l’alliance d’éléments volumiques et cohésifs, permettant de reproduire le scénariod’endommagement, et en particulier le couplage fissuration/délaminage. Cette démarchepourrait être élargie aux autres fixations étudiées et au Virtual Testing d’assemblages. Lesessais numériques permettraient de réduire considérablement le coût de développementdes fixations aveugles et seraient un outil essentiel pour leur optimisation / In the frame of the European project MAAXIMUS, aiming at decreasing the developmenttime and cost of a highly-optimized composite fuselage, this thesis focuses on “VirtualTesting”, applied to aeronautical blind fasteners into composite structures. Thanks toan experimental and numerical study, the mechanical behaviour of several fasteners havebeen studied under several loading cases (static and fatigue tensile tests, lap joint shearand pull-through tests), pointing out the main influential parameters. The numerical analysisof the installation is performed on one reference, being assumed that the method canbe enlarged to other fasteners. Installation sequence is well foreseen, both qualitatively (interms of sleeve shape and impact on the assembly) and quantitatively (in terms of preloadand influence of the grip). Out-of-plane behaviour of laminates is simulated, thanks to advanceddamage modelling using cohesive elements to account for the coupling betweenmatrix cracking and delamination. Damage scenario and structural failure are well foreseen,increasing existing knowledge on this type of loading. The combination of installationmodel and out-of-plane laminate modelling can now enable application of Virtual Testingon other mechanical tests to reduce development costs. Optimisation of blind fasteners is asecond path of study that could lead to a great decrease of assembly time by an increasedautomation

Submitted by Elza Cristina Jacobelli Chaves da Silva (cristina.jacobelli@hotmail.com) on 2018-10-01T02:14:14Z No. of bitstreams: 1 dissertação final para impressão.pdf: 2989524 bytes, checksum: ec5ac575e3b642d84bc53eafbd908671 (MD5) / Approved for entry into archive by Silvana Alvarez null (silvana@ict.unesp.br) on 2018-10-03T14:57:05Z (GMT) No. of bitstreams: 1 dissertação final para impressão.pdf: 2989524 bytes, checksum: ec5ac575e3b642d84bc53eafbd908671 (MD5) / Made available in DSpace on 2018-10-03T14:57:05Z (GMT). No. of bitstreams: 1 dissertação final para impressão.pdf: 2989524 bytes, checksum: ec5ac575e3b642d84bc53eafbd908671 (MD5) Previous issue date: 2018-08-22 / The practice of dentistry aims to guarantee hygiene and full oral health, however, this noble activity implies the generation of waste, which must be properly treated in order to minimize negative impacts on the environment and society. Many of the materials used in dentistry are potentially harmful to the environment if their disposal is not performed correctly. Because of this, it is essential to raise the awareness of dentists about the recommended management and disposal, with a view to mitigating, if not annulling, the harmful effects on the environment and the population. Inadequate disposal of dental waste results in pollution of the soil and water, with immeasurable consequences. In view of the enormous risk posed by the inadequate disposal of dental waste, it is necessary to determine which measures should be taken with a view to minimizing such risks as well as which bodies are competent to set guidelines and regulate the subject. Primordial is the awareness of the dentist, who is responsible for handling the compounds directly and discarding their waste. Equally important are regulation and oversight, which can be performed concurrently by different spheres of government. At federal level, Anvisa has legal competence to deal with the matter, including penalties for inappropriate conduct. However, given the shortage of personnel, federal supervision is not always carried out satisfactorily, which is why a greater participation of municipal administrations is fundamental in this process. The present study consisted of a survey carried out with 84 dentists in the city of Guaratinguetá-SP, whose main objective was to verify the destination that was being given to dental developers and dental fixatives, and, in the alternative, also to be aware of the ecological awareness of the participants. At the end of the research, it was identified that the great majority of dental surgeons promoted the disposal of waste in an incorrect manner, by discarding the sewage network (73.81%) and the environment (8.33%). It was also verified that 82.14% of the participants did not have in their academic formation any discipline that covered the discard theme of dental developers and fixators and 92,86% never attended a lecture or congress that dealt with the theme. Regarding the chemical composition of developers and fixatives, 78.31% of interviewees had no such knowledge. It is concluded that only a small number of professionals proceed correctly regarding the disposal of chemical residues, showing timely inclusion of content in the curriculum of the Dentistry courses. / O exercício da Odontologia visa garantir higidez e a plena saúde bucal, entretanto, essa nobre atividade implica na geração de resíduos, os quais devem ser devidamente tratados para que sejam minimizados os impactos negativos sobre o meio ambiente e a sociedade. Muitos dos materiais utilizados na Odontologia são potencialmente danosos ao meio ambiente, caso seu descarte não seja realizado da forma correta. Em virtude disto, mostra-se essencial a conscientização dos cirurgiões-dentistas acerca do manejo e descarte recomendado, com vistas a amenizar, senão anular, os efeitos nocivos ao meio ambiente e à população. O descarte inadequado dos resíduos odontológicos acarreta poluição do solo e das águas, tendo consequências imensuráveis. Diante do enorme risco ocasionado pelo descarte inadequado dos resíduos odontológicos, faz-se necessário apurar quais condutas devem ser tomadas com vistas a minimizar tais riscos bem como quais os órgãos competentes para fixar diretrizes e regulamentar o assunto. Primordial é a consciência do dentista, que é o responsável por manusear diretamente os compostos e descartar seus resíduos. Igualmente importantes são a regulamentação e a fiscalização, as quais podem ser desempenhadas, concorrentemente, pelas diferentes esferas de governo. A nível federal, a Anvisa detém competência legal para tratar do assunto, havendo inclusive penalidades para condutas inadequadas. Entretanto, dada a carência de pessoal, a fiscalização federal nem sempre é realizada a contento, motivo pelo qual uma maior participação das administrações municipais mostra-se fundamental nesse processo. O presente trabalho consistiu em pesquisa realizada com 84 cirurgiões-dentistas do município de Guaratinguetá-SP, cujo objetivo principal foi verificar a destinação que estava sendo dada aos resíduos de reveladores e fixadores odontológicos e, subsidiariamente, também tomar conhecimento da consciência ecológica dos participantes. Ao término da pesquisa, identificou-se que a grande maioria dos cirurgiões-dentistas promovia a destinação de resíduos de maneira incorreta, mediante descarte na rede de esgoto (73,81%) e no meio ambiente (8,33%). Verificou-se também que 82,14% dos participantes não tiveram em sua formação acadêmica nenhuma disciplina que abrangesse o tema descarte de reveladores e fixadores odontológicos e 92,86% jamais presenciaram palestra ou congresso que tratasse do tema. No tocante à composição química de reveladores e fixadores, 78,31% dos entrevistados não detinham tal conhecimento. Conclui-se que apenas pequena parcela dos profissionais procede corretamente quanto ao descarte dos resíduos químicos, mostrando oportuna a inclusão de conteúdo na grade curricular dos cursos de Odontologia.

As vigas compostas pregadas possuem vasta aplicação como material estrutural, desde vigas para instalações residenciais e industriais até longarinas de pontes de pequenos vãos, apresentando como principais vantagens o baixo custo e a facilidade de execução, não exigindo mão-de-obra qualificada. Este trabalho tem como objetivo o estudo teórico e experimental de vigas de madeira com seção composta I formadas por peças de madeira serrada e solidarizadas por pregos. São apresentados os critérios das normas EUROCODE 5, DIN1052 e NBR 7190, bem como a teoria a respeito do assunto. É avaliado o procedimento de cálculo da NBR 7190, em comparação com o EUROCODE 5, sendo realizada verificação experimental dos critérios destas normas, por meio de ensaios de flexão em protótipos de vigas compostas em escala natural. Os resultados obtidos demonstram que o modelo do EUROCODE 5 é o mais indicado para estimar a rigidez efetiva, tensões normais e de cisalhamento como também a força nos conectores / The built-up I beams are widely employed as structural elements, from residential and industrial facilities, to girders for bridges of small span. The fact that they do not demand skilled workmanship, the low cost and easiness of construction are their main advantages. This research aims at the theoretical and experimental analysis of built-up I beams, made of sawn elements nailed jointed. The EUROCODE 5, DIN 1052 and NBR 7190 criteria as well as the basic theory are presented. The design procedure adopted by NBR 7190 is compared to the EUROCODE 5 one. Experimental evaluation of these criteria is made subjecting built-up beam prototype to bending tests. The results should that the EUROCODE criteria is the most recommended for estimate the effective rigidity, normal and shear stresses as well as the load on a fastener

Este trabalho consiste numa revisão bibliográfica sobre ligações em estruturas de aço. Inicialmente são abordados os dispositivos de ligação, enfatizando os tipos e as características estruturais dos conectores, os processos de soldagem mais empregados nas estruturas de aço e suas implicações. A seguir são apresentados os aspectos mais importantes sobre o comportamento estrutural de parafusos e soldas e a avaliação da resistência com base na norma brasileira NBR 8800 e nas principais normas estrangeiras aplicáveis. Finalmente, são apresentados e discutidos os modelos teóricos clássicos usualmente empregados para a avaliação de solicitações em ligações parafusadas e soldadas. / This work gives a reference review on steel structure connections. First, connection designs are discussed, emphasizing the types of fasteners, their characteristics, the most common employed welding processes for steel structures and the technical implications. It is also presented the most important aspects regarding the structural behaviour of bolts, welds and the strength evaluation based on the Brazilian code NBR 8800, as well as on the main known foreign codes. Finally the classical theoretical analysis often adopted for the evaluation of welded and bolted connections are presented and discussed.

This document will outline the findings of three separate and independent studies: Study 1: In or around 1972, an experimental building was constructed. One of the intents of the construction project was to demonstrate advancements in wood building construction design. It was value-engineered throughout. That is, its materials and systems were intended to function at or near design capacity. In 2019, part of the roof of the structure collapsed. This case study investigates two potential factors that led to the failure: stress concentration in excess of the 12 allowable stress for 2 × 4 web members and insufficient plywood sheathing to support live loads 13 caused by large rain events. Study 2: As a building material, cross laminated timber (CLT) has exponentially grown in popularity recently. Although performing superior to numerous other popular building materials, a consistent issue presented in wood construction is the effect of moisture on performance. This study looks to investigate the effect of moisture content on the performance of a 2-way dowel type fastener system loaded in shear perpendicular to the major strength axis. It was found that the peak load capacity of the specimens was not affected by the moisture content of the CLT. However, yield strength increased as the moisture content decreased. Lastly it was found that the failure mode changed from ductile to brittle as specimens became drier than 12% moisture content by mass. Study 3: Inherently, the weak point of any structure is the connection system. This phenomenon is particularly apparent in wooden structures as dowel type fasteners place tremendous amounts of stress perpendicular to the grain of the wood, as well as shear stress under the bolt. In hopes of mitigating this behavior, fiberglass reinforcement of these samples is examined to see if both failure mode as well as overall performance of these fasteners could be improved with reinforcement. It was found that fiberglass significantly reduced the standard deviation of failure strength of fasteners, significantly increased the overall strength of the fasteners, increased the efficiency of the fasteners, and finally increased the probability of bearing failure opposed to block shear failure.

In this dissertation, we have developed computer vision methods for measurement of rail gauge, and reliable identification and localization of structural defects in railroad tracks. The rail gauge is the distance between the innermost sides of the two parallel steel rails. We have developed two methods for evaluation of rail gauge. These methods were designed for different hardware setups: the first method works with two pairs of unaligned video cameras while the second method works with depth maps generated by paired laser range scanners. We have also developed a method for detection of rail defects such as damaged or missed rail fasteners, tie clips, and bolts, based on correlation and MACH filters. Lastly, to make our algorithms perform in real-time, we have developed the GPU based library for parallel computation of the above algorithms. Rail gauge is the most important measurement for track maintenance, because deviations in gauge indicate where potential defects may exist. We have developed a vision-based method for rail gauge estimation from a pair of industrial laser range scanners. In this approach, we start with building a 3D panorama of the rail out of a stack of input scans. After the panorama is built, we apply FIR circular filtering and Gaussian smoothing to the panorama buffer to suppress the noise component. In the next step we attempt to segment the rail heads in the panorama buffer. We employ the method which detects railroad crossings or forks in the panorama buffer. If they are not present, we find the rail edge using robust line fit. If they are present we use an alternative way: we predict the rail edge positions using Kalman filter. In the next step, common to both fork/crossings conditions, we find the adjusted positions of rail edges using additional clustering in the vicinity of the edge. We approximate rail head surface by the third degree polynomial and then fit two plane surfaces to find the exact position of the rail edge. Lastly, using rail edge information, we calculate the rail gauge and smooth it with 1D Gaussian filter. We have also developed a vision-based method to estimate the rail gauge from a pair of unaligned high shutter speed calibrated cameras. In this approach, the first step is to accurately detect the rail in each of the two non-overlapping synchronous images from the two cameras installed on the data collection cart by building an edge map, and fitting lines into the edge map using the Hough transform, and detecting persistent edge lines using a history buffer. After railroad track parts are detected, we segment rails out to find rail edges and calculate the rail gauge. We have demonstrated how to apply Computer Vision methods (the correlation filters and MACH filters in particular) to find different types of railroad elements with fixed or similar appearance, like railroad clips, bolts, and rail plates, in real-time. Template-based approaches for object detection (correlation filters) directly compare gray scale image data to a predefined model or template. The drawback of the correlation filters has always been that they are neither scale nor rotation invariant, thus many different filters are needed if either scale or rotation change. The application of many filters cannot be done in real-time. We have succeeded to overcome this difficulty by using the parallel computation technology which is widely available in the GPUs of most advanced graphics cards. We have developed a library, MinGPU, which facilitates the use of GPUs for Computer Vision, and have also developed a MinGPU-based library of several Computer Vision methods, which includes, among others, an implementation of correlation filters on the GPU. We have achieved a true positive rate of 0.98 for fastener detection using implementation of MACH filters on GPU. Besides correlation filters, MinGPU include implementations of Lucas-Kanade Optical Flow, image homographies, edge detectors and discrete filters, image pyramids, morphology operations, and some graphics primitives. We have shown that MinGPU implementation of homographies speeds up execution time approximately 600 times versus C implementation and 8000 times versus Matlab implementation. MinGPU is built upon a reusable core and thus is an easily expandable library. With the help of MinGPU, we have succeeded to make our algorithms work in real-time.

No description available.

Master of Science / Pallets are used all over the world in the field of distribution. The strength values associated with a pallet have been thoroughly investigated by many different researchers; however, the stiffness values associated with pallet joints have not. The goal of this work was to investigate the stiffnesses associated with pallets joints made with lag screws and carriage bolts. It is important to understand that different materials, fastening methods, and design considerations can have a huge impact on the stiffness of the joint. This paper will discuss the various tests that were used to measure the actual stiffness of pallet joints and the results of those tests. Afterwards, the researchers detail their attempt to predict the stiffness using an equation created from the actual test data. Finally, by understanding the effects of these various factors, better pallet designs can be created that are both safer and stronger using the investigated alternative fasteners.

Este trabalho apresenta uma proposta de método de ensaio para determinação da resistência de ligações em peças estruturais de madeira por chapas com dentes estampados e também verifica os modos de ruptura destas ligações. Para esta finalidade foram realizados ensaios com 5 (cinco) espécies de madeira classificadas de acordo com as classes de resistência apresentadas no projeto da nova norma brasileira para estruturas de madeira, a PNBR 7190/1996 - Projeto de Estruturas de Madeira. No trabalho são verificados 3 (três) modos básicos de ruptura das ligações, a saber: tração da chapa, cisalhamento da chapa e arrancamento dos dentes da chapa da peça de madeira. Dentro de cada modo de ruptura verifica-se os efeitos da variação da posição da chapa em relação à direção de aplicação da força. Determina-se também a resistência da ligação de acordo com o proposto pelo projeto da nova norma brasileira para estruturas de madeira (PNBR 7190, 1996). / The aim of this work is to propose a test method to determine the strength and to verify failure modes of timber joints made with metal connectors plate. To this purpose, several tests were made with 5 species of wood, which were classified according to the strength class introduced in the new Brazilian Standard for Timber Structures, NBR 7190/1996 - Timber Structure Project. In this work are verified 3 failure modes: metal connector plates under shear force and pure tension force, and lateral resistance strength of metal connector plate teeth. For each failure mode is verified the effect of the position of the plate under the direction of force. The resistance of joints are determine in agreement to the new Brazilian Standard for Timber Structures.

<p>Wind loads acting on wooden building structures need to be dealt with adequately in order to ensure that neither the serviceability limit state nor the ultimate limit state is exceeded. For the structural designer of tall buildings, avoiding the possibly serious consequences of heavy wind loading while taking account at the same time of the effects of gravitation can be a real challenge. Wind loads are usually no major problem for low buildings, such as one- to two-storey timber structures involving ordinary walls made by nailing or screwing sheets of various types to the frame, but when taller structures are designed and built, serious problems may arise.</p><p>Since wind speed and thus wind pressure increases with height above the ground and the shear forces transmitted by the walls increase accordingly, storey by storey, considerable efforts can be needed to handle the strong horizontal shear forces that are exerted on the bottom floor in particular. The strong uplift forces that can develop on the wind side of a structure are yet another matter that can be critical. Accordingly, a structure needs to be anchored to the substrate or to the ground by connections that are properly designed. Since the calculated uplift forces depend very much upon the models employed, the choice of models and simplifications in the analysis that are undertaken also need to be considered carefully.</p><p>The present licentiate thesis addresses questions of how wind loads acting on multi-storey timber buildings can be best dealt with and calculated for in the structural design of such buildings. The conventional use of sheathing either nailed or screwed to a timber framework is considered, together with other methods of stabilizing timber structures. Alternative ways of using solid timber elements for stabilization are also of special interest.</p><p>The finite element method was employed in simulating the structural behaviour of stabilizing units. A study was carried out of walls in which sheathing was nailed onto a timber frame. Different structural levels were involved, extending from modelling the performance of a single fastener and of the connection of the sheathing to frame, to the use of models of this sort for studying the overall structural behaviour of wall elements that possess a stabilizing function. The results of models used for simulating different load cases for walls agreed reasonably well with experimental test results. The structural properties of the fasteners binding the sheathing to the frame, as well as of the connections between the members of the frame were shown to have a strong effect on the simulated behaviour of shear wall units.</p><p>Regarding solid wall panels, it was concluded that walls with a high level of both stiffness and strength can be produced by use of such panels, and also that the connections between the solid wall panels can be designed in such a way that the shear forces involved are effectively transmitted from one panel to the next.</p>