A renda de bilros é uma tipologia da renda que utiliza bilros (pequenos fusos onde se enrolam os fios) para a sua produção; de tradição secular, aportou no Brasil por meio das mulheres portuguesas. O Estado do Ceará tornou-se um importante centro da tradição, sendo citado em diversas publicações, tornando a renda de bilros conhecida como renda do Ceará em outras localidades brasileiras. Os conceitos acerca do artesanato e do design foram debatidos a fim de analisar a técnica de rendar com bilros e seu uso. Também foi analisada a trajetória que a tradição percorreu desde a primeira publicação a respeito do tema: de 1948 até o ano de 2013, com o propósito de compreender as mudanças ocorridas na mesma. Foram descritos os utensílios utilizados na fabricação da renda de bilros, bem como sua técnica e pontos. Um breve relato acerca de como a técnica tem se desenvolvido em Morros da Mariana (PI) e Florianópolis foram realizados a fim de validar outras formas de manejo da tradição / Bobbin lace is a type of lace craft which utilizes bobbins (small spindles around which the threads are wound) in its production, it is a secular tradition which was brought to Brazil by Portuguese women. The state of Ceara became an important hub of this tradition, being cited in various publications and as a result bobbin lace came to be known as Ceara lace in other places throughout Brazil. The concepts surrounding the craft and the design have been discussed in order to analyse the bobbin lace technique and its use. Also, trajectory of bobbin lace was assessed, since the first publication regarding the subject: from 1948 until 2013, with the objective of understanding the changes that took place in the craft. The tools which are used in the fabrication of bobbin lace were described, as well as the technique and points. Brief reports were written about how the technique has developed in Morros da Mariana (PI) and Florianopolis, with the aim of validating other forms of the tradition

A renda de bilros é uma tipologia da renda que utiliza bilros (pequenos fusos onde se enrolam os fios) para a sua produção; de tradição secular, aportou no Brasil por meio das mulheres portuguesas. O Estado do Ceará tornou-se um importante centro da tradição, sendo citado em diversas publicações, tornando a renda de bilros conhecida como renda do Ceará em outras localidades brasileiras. Os conceitos acerca do artesanato e do design foram debatidos a fim de analisar a técnica de rendar com bilros e seu uso. Também foi analisada a trajetória que a tradição percorreu desde a primeira publicação a respeito do tema: de 1948 até o ano de 2013, com o propósito de compreender as mudanças ocorridas na mesma. Foram descritos os utensílios utilizados na fabricação da renda de bilros, bem como sua técnica e pontos. Um breve relato acerca de como a técnica tem se desenvolvido em Morros da Mariana (PI) e Florianópolis foram realizados a fim de validar outras formas de manejo da tradição / Bobbin lace is a type of lace craft which utilizes bobbins (small spindles around which the threads are wound) in its production, it is a secular tradition which was brought to Brazil by Portuguese women. The state of Ceara became an important hub of this tradition, being cited in various publications and as a result bobbin lace came to be known as Ceara lace in other places throughout Brazil. The concepts surrounding the craft and the design have been discussed in order to analyse the bobbin lace technique and its use. Also, trajectory of bobbin lace was assessed, since the first publication regarding the subject: from 1948 until 2013, with the objective of understanding the changes that took place in the craft. The tools which are used in the fabrication of bobbin lace were described, as well as the technique and points. Brief reports were written about how the technique has developed in Morros da Mariana (PI) and Florianopolis, with the aim of validating other forms of the tradition

In this thesis, friction stir channeling (FSC) and its process parameters influence on geometry, surface quality and productivity are explored. The probe of the friction stir processing (FSP) tool used to perform these tests was a modified submerged bobbin tool made of MP 159 Co-Ni alloy. The body was made from H13 tool steel. To find the optimal channel conditions for a targeted range of process parameters, multiple 6061 aluminum samples were prepared with a U shape guide to test the effects of different spindle speeds and feed rates. Using a gantry-type computer numerical control (CNC) friction stir welding (FSW) machine, the aluminum coupons were subjected to calibration experiments, force control tests, and an increased production rate to test these effects. It was found through experimentation that the programmed feed rates, spindle speeds and forces produced by the machine had an impact on the channel geometry. It was determined from the force-controlled setup that 8.46 mm/s at 750 RPM was the best combination of results for the four conditions tested on a CNC friction stir processing-machine. It was then tested at 10.58 mm/s at 800 RPM, which had comparable results with the best combination of input parameters from the force-controlled runs which demonstrates the utility of the process in high production settings. Finally, a proof-of-concept experiment was performed on a robotic arm outfitted with a FSW holder, showing acceptable results. This is a validation of its future implementation in the manufacturing of large parts for lightweight, aerospace, and automotive applications.

No description available.

Dans le domaine des matériaux métalliques, les techniques d’assemblage par soudageconduisent à des réductions de masse et de coûts importantes susceptibles d’intéresserles industries aéronautiques. Néanmoins, les procédés de soudage classiquespar fusion ne s’appliquent pas aux dernières générations d’alliages d’aluminium aéronautiques.Dans ce contexte, le procédé de soudage Friction Stir Welding présentedes atouts considérables, de nature à rendre compétitives les structures métalliquesface à la montée en puissance des matériaux composites.L’objectif de cette thèse est double. Il s’agit d’une part d’améliorer notre compréhensiondu procédé de soudage Friction Stir Welding Bobbin Tool puis dans undeuxième temps de proposer une méthodologie visant à prédire les paramètres desoudage optimaux.Afin de mener à bien ces objectifs, des essais de soudage ont été menés pour troisalliages d’aluminium aéronautique, incluant deux alliages d’aluminium-lihtium, etdeux épaisseurs, représentatives d’une jonction de peau de fuselage. Les résultatsd’essais ont par la suite été exploités et ont permis de mettre en évidence des corrélationsentre paramètres de soudage, température, puissance et malaxage du noyausoudé.Dans un troisième temps, afin de supporter la démarche expérimentale, des outilsde simulation ont été utilisés. Un modèle thermo-fluide local a été développé afinde simuler les phénomènes de malaxage dans le noyau soudé. A l’échelle globale, unmodèle thermique a permis de reproduire fidèlement les phénomènes de diffusion dela chaleur dans la structure. Enfin, le couplage des deux modèles a montré qu’il étaitpossible de simuler puis de prédire un domaine de soudabilité. / In the field of metallic materials, welding technologies can provide significantmass reductions and cost savings to aircraft industries. Nevertheless, classical fusionwelding processes can not be applied to last generations of aeronautical aluminiumalloys. In this context, Friction Stir Welding offers many advantages and can helpmetallic parts to face the build up of composite materials.This thesis has mainly two objectives. We aim first at improving our understandingof Friction Stir Welding with Bobbin Tool and then at proposing a kind ofmethodology able to predict optimal welding parameters.Welding trials were carried out using three aeronautical aluminium alloys includingtwo aluminium lithium and two thicknesses representative of a fuselagejunction. Results were analyzed and some correlations were found between weldingparameters, temperature and stirring of the weld nugget.This work was also supported by several modeling tools. A local thermo-fluidapproach has been used to simulate stirring of the material in the weld nugget. Aglobal thermal model has been used to simulate heat diffusion in the structure. Then,a coupled approach of these previous modeling tools shows that it was possible tonumerically predict a processing window.

Bobbin lace is a 500-year-old art form in which threads are braided together in an alternating manner to produce a lace fabric. A key component in its construction is a small pattern, called a bobbin lace ground, that can be repeated periodically to fill a region of any size. In this thesis we present a mathematical model for bobbin lace grounds representing the structure as the pair (Δ(G), ζ (v)) where Δ(G) is a topological embedding of a 2-regular digraph, G, on a torus and ζ(v) is a mapping from the vertices of G to a set of braid words. We explore in depth the properties that Δ(G) must possess in order to produce workable lace patterns. Having developed a solid, logical foundation for bobbin lace grounds, we enumerate and exhaustively generate patterns that conform to that model. We start by specifying an equivalence relation and define what makes a pattern prime so that we can identify unique representatives. We then prove that there are an infinite number of prime workable patterns. One of the key properties identified in the model is that it must be possible to partition Δ(G) into a set of osculating circuits such that each circuit has a wrapping index of (1,0); that is, the circuit wraps once around the meridian of the torus and does not wrap around the longitude. We use this property to exhaustively generate workable patterns for increasing numbers of vertices in G by gluing together lattice paths in an osculating manner. Using a backtracking algorithm to process the lattice paths, we identify over 5 million distinct prime patterns. This is well in excess of the roughly 1,000 found in lace ground catalogues. The lattice paths used in our approach are members of a family of partially directed lattice paths that have not been previously reported. We explore these paths in detail, develop a recurrence relation and generating function for their enumeration and present a bijection between these paths and a subset of Motzkin paths. Finally, to draw out of the extremely large number of patterns some of the more aesthetically interesting cases for lacemakers to work on, we look for examples that have a high degree of symmetry. We demonstrate, by computational generation, that there are lace ground representatives from each of the 17 planar periodic symmetry groups. / Graduate / 0389 / 0984 / 0405 / veronikairvine@gmail.com

PROBLEM - The bobbin friction stir welding (BFSW) process has potential benefits for welding thin sheet aluminium alloy. The main benefits of friction stir welding over conventional thermal welding processes are minimisation of energy usage, no need for consumables, potential for good weld quality without porosity, no fumes, minimal adverse environmental effects (green), minimal waste (lean), and reduced threats to personal health and safety. The BFSW process has further advantages over conventional friction stir welding (CFSW) in the reduction of welding forces, faster welding, and less fixturing. It is especially attractive to industries that join thin sheet material, e.g. boat-building. The industrial need for this project arose from the desire to apply the technology at a ship manufacturing company, INCAT located in Hobart, Tasmania, Australia. However there are peculiar difficulties with the specific grade of material used in this industry, namely thin sheet aluminium Al6082-T6. Early efforts with a portable friction stir welding machine identified the process to have low repeatability and reproducibility, i.e. process-instability. There are a large number of process variables and situational factors that affect weld quality, and many of these are covert. This is also the reason for divergent recommendations in the literature for process settings. PURPOSE - The main purpose of this research was to identify covert variables and better understand their potentially adverse effects on weld quality. Therefore, this thesis investigated the hidden variables and their interactions. Developing this knowledge is a necessity for making reliable and repeatable welds for industrial application. APPROACH - An explorative approach that focused on the functional perspective was taken. An extensive empirical testing programme was undertaken to identify the variables and their effects. In the process a force platform and BFSW tools were designed and built. A variety of machine platforms were used, namely portable friction stir welding, manual milling machine and computer numerical control (CNC) milling machine. The trials were grouped into 14 test plans. These are tool shoulder gap, spindle and travel speed, tool features, machines, tool fixation, machinery, welding direction, plate size (width and dimension), support insulation, tool materials, substrate properties and fixation. For the welded plates besides visual inspection of the weld, current, force, and temperature were measured. The Fourier transform was used to analyse the frequency response of machines. Also the welded samples were tested to the maritime standards of Det Norske Veritas (DNV). A number of relationships of causality were identified whereby certain variables affected weld quality. A model was developed to represent the proposed causality using the IDEF0 systems engineering method. FINDINGS - From these trials six main variables have been identified. These are tool features, spindle speed, travel speed, shoulder gap compression, machine variability, tool and substrate fixation. A rigid system is required for a consistent weld results. Under this condition, full pin features (threads and flats) need to be used to balance the adverse effects of individual features. It has been shown that fabricated bobbin tools with sharp edges can cause cuts and digging thus this feature should be avoided. Additionally, the substrate should have continuous interaction with the tool so the shoulder interference needs to be fixed and well-controlled. It is found that the compression generated by the shoulder towards the substrate helps material grabbing for better tool-substrate interaction. It is also shown that tool entry causes ejection of material and hence an enduring mass deficit, which manifests as a characteristic tunnel defect. The new explanation of the formation, origin and location of this defect has been explained. Material transportation mechanisms within the weld have been elucidated. It is also found that the role of the travel speed is not only to control heat generation but also for replacing the deficit material. Additionally, heat supplied to the weld depends not only on thickness, but also the width of the plate. Different types of machine cause an interaction in the material flow through their controller strategies. Jerking motion can occur at a slow travel speed, which also alters the way material is being transported. The Fourier transform (FFT) has been used to identify the characteristics of good and bad BFSW welds. This has the potential to be expanded for real-time process control. IMPLICATIONS - Tool deflection and positioning, material flow and availability are identified as affecting weld quality through stated mechanisms. The impact is even more severe when involving thin-plate aluminium. For the industry to successfully adopt this technology the process typically needs tight control of shoulder gap, tool strength and stiffness, feature fabrication, substrate and tool fixation. Additionally spindle and travel speed need to be adjusted not only based on the type of materials and thickness, but also the width, type of machine and method of tool entry. ORIGINALITY - New data are presented, which lead to new insights into the welding mechanics, production settings, material transportation and weld defects for BFSW on thin sheet material. The conventional idea that the welding tool has a semi-steady interaction with the substrate is not supported. Instead the interaction is highly dynamic, and this materially affects the weld-quality, especially in the difficult-to-weld material under examination. Factors such as shoulder gap, tool and substrate fixation compliance and machine types emerge as variables that need to be given attention in the selection of process parameters. The causal relationships have been represented in a conceptual model using an IDEF0 system approach. This study has made several original contributions to the body of knowledge. First is the identification of previously hidden variables that effect weld formation for the fixed gap BFSW process. The second contribution is a new way of understanding the material transportation mechanics within the weld. This includes the flow around the pin in the plane of the weld, the vertical transportation of material up the pin, the formation of turbulent-like knit lines at the advancing side, and the formation of tunnel defects. Also included here is a new understanding of how material deficit arises at tool entry and exit, and from flash/chips, and how this contributes to the tunnel weld defect. In addition, new understandings of the role of feed rate have been identified. Related to the material transportation, the work has also identified the importance of an interference fit between the substrate and tool. A third contribution is the identification of the dynamic interaction between tool and substrate. This identifies the important role rigidity plays. Associated with this is the identification of frequency characteristics of the motors under load. The fourth contribution is identification of the specific process settings for the difficult-to-weld material of AL6082-T6. The fifth contribution is the development of a novel method of fabricating bobbin friction stir welding tools as embodied in a patent application.

Made available in DSpace on 2014-12-17T14:52:59Z (GMT). No. of bitstreams: 1 AngelaDC_DISSERT_1-67.pdf: 6453469 bytes, checksum: 362c5cd4531649f45bbec6e910f57e4b (MD5) Previous issue date: 2010-12-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This paper analyzes the development of Bobbin Lace and Design workshops, in the neighborhood of Vila de Ponta Negra (in Natal - RN, Brazil), which proposed contents and practices for its learning and teaching that would compose a possible model for a hybrid Workshop of Bobbin Lace and Lace Design. This research was based on Ergonomic Work Analysis, a methodology used by Ergonomics to analyze work in a wide approach, considering cognitive, social, organizational, as well as other aspects which are relevant to the study of the working situation, in terms of learning/teaching, as addressed on this paper. Some steps of the above mentioned methodology were followed in order to understand the activity of Bobbin Lace craftswomen, by means of bibliographical research centered on this activity. The instruments used for collecting data comprise of conversational actions, analysis of collective work, and spontaneous as well as provoked verbalizations. The adaptations performed in the process of learning/teaching Bobbin Lace for the achievement of Bobbin Lace and Design workshops became instrumental for the continuity of that tradition, attracting new apprentices to this art/craft causing to revitalize a network of handicraft economical activities linked to the Bobbin Lace production, such as the making of cushion, bobbins and trestles / Este trabalho descreve e analisa o desenvolvimento das oficinas de Renda de Bilro e de desenho da Renda de Bilro na Vila de Ponta Negra (Natal - RN), no intuito de propor conte?dos e pr?ticas do Ensino-Aprendizagem num poss?vel modelo de oficina H?brida - Renda de bilro e desenho da Renda de Bilro. A pesquisa fundamentou-se na An?lise Ergon?mica do Trabalho (AET), metodologia utilizada pela ergonomia que busca analisar o trabalho numa abordagem abrangente, considerando aspectos de ordem cognitiva, social, organizacional, assim como outros aspectos relevantes ao estudo da situa??o de trabalho, em termos de ensinoaprendizagem, abordados neste projeto. Seguiram-se algumas etapas da metodologia supracitada para o entendimento da atividade da Rendeira de Bilro, atrav?s de pesquisas bibliogr?fica e situadas da atividade. Os instrumentos de pesquisa utilizados para coleta dos dados compreendem a??es conversacionais, an?lises coletivas do trabalho, verbaliza??es espont?neas e provocadas. As adapta??es realizadas no processo ensino-aprendizagem da Renda de Bilro para a realiza??o das oficinas pr?ticas de Renda de Bilro e do Desenho da Renda tornaram-se um instrumento para a continuidade da tradi??o, atraindo novos aprendizes ? arte-of?cio e proporcionando a ativa??o de uma rede de atividades econ?micas artesanais ligadas a produ??o da renda de bilro, tais como a produ??o de almofadas, bilros e cavaletes

nÃo hà / De Renda e de Pele à uma pesquisa que trata de uma imersÃo em procura de expressÃes artesanais, caracterÃsticas do estado do CearÃ-Brasil, especificamente a Renda de Bilro. Relato aqui uma experiÃncia na qual fiz apropriaÃÃes de peÃas feitas por artesÃs locais, que derivaram em uma sÃrie de trabalhos artÃsticos onde explorei a correspondÃncia plÃstica do tecido com a pele humana, suas marcas e a ligaÃÃo tangÃvel e poÃtica das duas superfÃcies com o sentido do tato. Esse percurso me permitiu tambÃm refletir em torno ao meu processo criativo e aos procedimentos anteriormente utilizados, para aplicÃ-los e compartilhÃ-los nesta busca, o que foi possÃvel devido a uma metodologia que deu relevÃncia à prÃtica e à troca de conhecimentos dentro de um grupo de pesquisa. AlÃm disso, trouxe à discussÃo a voz de alguns teÃricos que incentivaram e deram consistÃncia Ãs minhas reflexÃes, e artistas que se cruzam com o meu fazer, seja pelo uso da mesma matÃria (tecido-fio), ou pelo jeito de proceder para criar. / Of lace and skin is a research about an immersion in search of characteristic artisanal expressions in the state of CearÃ, Brasil, specifically the bobbin lace. Here, I recount an experience in which I did appropiations of pieces made by local artisans that developed into a number of artistic works where I explored the plastic correlation between the cloth and the human skin, their markings and the tangible and poetic connection of both surfaces with the sense of touch. This journey also allowed me to reflect upon my creative process and the procedures I had used previously. Consequently, I was able to apply and share them in this search, something that was possible due to a method that gave importance to the practice and the sharing of knowledge within a research group. In the same way, I brought to discussion the voice of some theorists that fostered and gave consistence to my reflections, and also artists who share my work, either for using the same material (cloth â thread) or for the creation patterns they employ.

Orientador: Oscar Antonio Braunbeck / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-15T19:34:58Z (GMT). No. of bitstreams: 1 Silveira_HenriqueLeandro_M.pdf: 3800954 bytes, checksum: e36878378c455fc352fe2da2f4432883 (MD5) Previous issue date: 2010 / Resumo: A palha da cana-de-açúcar apresenta um grande potencial para ser utilizada na co-geração de energia. Entretanto, essa energia disponível não tem sido totalmente aproveitada nas usinas, em parte devido aos custos elevados relacionados ao seu transporte do campo para a indústria, e em parte associado às deficiências no mercado de máquinas específicas para o seu recolhimento e adensamento. A palha in natura apresenta baixas densidades, o que eleva os custos de transporte e armazenamento, dado pela subutilização de carga dos caminhões e espaço físico dos pátios. O que se tem praticado nas usinas é a tentativa do uso de máquinas forrageiras e enfardadoras, que foram projetadas para a cultura do feno, resultando assim em baixos rendimentos operacionais quando utilizadas com palha de cana-de-açúcar, além de incorporar matéria mineral indesejável. Pesquisas revelaram que a corda de amarração utilizada para inibir a relaxação dos fardos prismáticos e cilíndricos provenientes das enfardadoras é responsável por 40% dos custos totais destes processos. Neste trabalho é proposto um novo princípio de adensamento para a palha de cana-de-açúcar, onde as folhas são compactadas mediante aplicação de torção visando à formação de corda contínua, que pode ser enrolada em bobinas dispensando assim os complexos sistemas de amarração das enfardadoras. A densidade teórica alcançada pela bobina formada com a corda de palha foi estimada por modelos matemáticos. Uma abrangente modelagem envolvendo as forças de compactação na corda devidas à torção é apresentada. Foram realizados experimentos em protótipo correlacionando o torque aplicado na corda com a sua densidade aparente, além de ensaios envolvendo a formação de corda contínua, visando avaliar as condições de viabilidade técnica do processo. Os resultados obtidos indicaram que foi viável tecnicamente a formação de corda contínua e estruturada a partir de folhas secas de cana-de-açúcar utilizando o princípio de torção originada por atrito; a densidade aparente da corda de palha ficou próxima das densidades aparentes dos fardos cilíndricos e prismáticos obtidos pelas enfardadoras convencionais; a demanda de torque foi menor para a corda de menor diâmetro; a densidade aparente teórica da bobina foi inferior às densidades aparentes dos fardos cilíndricos; todos os ensaios apresentaram relaxação de torque no decorrer do tempo; o princípio apresenta limitações e demanda pré-requisitos indispensáveis para o perfeito funcionamento. / Abstract: Sugar cane straw presents a great potential to be used in energy cogeneration. However, this potential has not been fully explored at the mills, in part due to the high costs associated with transport from field to industry, and partly linked to the market deficiencies of specific equipment for their recovery and compaction. The straw in nature presents low density, which increases the cost of transport and storage, due to the sub utilization of load capacity trucks and requirement of space in the courtyards. What has been practiced at mills are some experiments using forages and balers machines, which were designed for hay harvesting, resulting in lower operating income when used for sugar cane straw, as well as incorporating undesirable mineral matter. Research showed that the mooring rope used to inhibit the relaxation of prismatic and cylindrical bales from the balers is responsible for 40% of the total costs of these processes. This dissertation presents a proposes of a new principle for sugar cane straw compaction, where the leaves are compressed by applying torque in order to form a continuous yarn that can be wrapped into coils without complex balers mooring systems. The theoretical density achieved by the coil formed with straw rope was estimated by mathematical models. A comprehensive modeling involving the compression forces on the rope due to torsion is presented. Experiments were carried out using a prototype in order to observe the torque applied to the rope with its density correlation. Experiments involving the formation of continuous rope, to evaluate the technical feasibility of the process were also conducted. The results indicated that it was technically possible to form a continuous and structured rope from dry leaves of sugar cane using the principle of torque originate by friction; the density of straw rope was close to the apparent densities of the cylindrical and prismatic bales obtained by conventional balers; the torque demand was lower for ropes with smaller diameter; the theoretical density of the coil was less than the apparent densities of the bale; all trials showed relaxation of torque over time; the principle is limited and demand pre- established parameters for its perfect operation. / Mestrado / Maquinas Agricolas / Mestre em Engenharia Agrícola