Este estudo apresenta uma investigação sobre a possibilidade de adotar o processo de solda por agitação e fricção, ou \"friction stir welding\" em substituição ao processo usual de fixação por rebitagem, na construção de um painel de fuselagem aeronáutica de dimensões compatíveis com uma aeronave regional com capacidade aproximada de cinqüenta assentos. A investigação avalia aspectos técnicos de engenharia, tais como capacidade de unir materiais heterogêneos, resistência mecânica, vida em fadiga da estrutura, aspectos de produtividade e custos associados. O processo de solda por agitação e fricção ocorre em estado sólido, não requer a introdução de um terceiro material ou qualquer tipo de arco elétrico ou atmosfera de gás inerte. Os materiais a serem unidos não atingem o ponto de fusão, mas são submetidos à severa deformação plástica, sendo misturados sem que haja fusão. As características mecânicas resultantes dos componentes soldados são equivalentes ou superiores às características dos componentes rebitados. Sob o ponto de vista econômico, existem ganhos em redução de custos de mão de obra e aumento na velocidade de produção, quando comparado ao processo de rebitagem. / This study presents an investigation about the possibility of use friction stir welding process to replace the usual riveting process to build an aeronautic fuselage panel which has its dimensions compatible to a fifty seats regional aircraft. The investigation evaluates engineering technical aspects as the capability to join dissimilar materials, the mechanical strength, structure\'s fatigue life, productivity aspects and associated costs. Friction stir welding is a solid state process where a third material deposition is not required, as well is not required any electric arc or inert gas atmosphere. The materials to be joined do not reach the fusion point, but are subjected to severe plastic deformation, being mixed without melting. The mechanical behavior of welded components is equivalent or better than the behavior of riveted components. From financial standpoint, there are benefits on labor costs reduction and increased production rate, when compared to the riveting process.

This thesis focuses on the application of case based reasoning (CBR) to welding fixtures in a computer aided design (CAD) environment. Modular fixtures have become more popular in previous years due to the creation of flexible manufacturing systems. Modular fixtures, since they are composed of many standardized parts, require much iteration to produce a full fixture design. This process is made more complicated when it is applied to more complex parts such as welding assemblies. In an effort to simplify fixture design for such complicated parts, researchers have been working on integrating fixture design into CAD packages. These efforts, generally known as computer aided fixture design (CAFD), do not focus on the transition of experience from more experienced designers but only provide a structure and a virtual environment to create fixtures. The research presented in this thesis will apply to this area. Case based reasoning (CBR) is a method of using previous cases to help aid the development of solutions to new problems. Applied to CAFD, this method is reduced to the application of a database and a retrieval and adaptation system. Current research on CAFD and CBR is limited to only proposing systems for machining fixtures. This thesis presents a methodology of a CAFD and CBR system that is dedicated to welding assemblies and fixtures. The focus is on creating an indexing system that adequately represents the workpiece and fixture, a retrieval system that accurately recovers the previous cases, and a method that integrates designer feedback in each process. The results of this thesis will be shown in a case study using an automobile muffler fixture assembly to define each idea of the methodology and to provide an example.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by Thomas David Burleigh. / M.S.

Orientador: Yukio Kobayashi / Banca: Carlos Alberto Soufen / Banca: Juno Gallego / Resumo: O objetivo desse trabalho é analisar cientificamente a realidade encontrada no chão de fábrica de uma empresa fabricante de equipamentos agrícolas comparada aos cuidados teoricamente requeridos na soldagem MAG robotizada e MAG PULSADO de dois aços dissimilares, sendo um aço comum ao carbono, o aço ABNT 6655 LN28, e o outro um aço de baixa liga, o aço SAE 8620. Recomenda-se da literatura que na soldagem do aço SAE 8620 seja utilizado o pré-aquecimento, dessa forma será então analisada a influência da temperatura de pré-aquecimento e do tecimento na microestrutura e na resistência da junta soldada. Para esse objetivo serão soldados vários corpos de prova sob diferentes temperaturas de pré-aquecimento e condições de tecimento. Na análise será considerada a microestrutura resultante na zona termicamente afetada composta pelo material SAE 8620 e a zona fundida, a resistência a tração e ao impacto da junta soldada obtida no processo e a dureza na zona termicamente afetada. Concluiremos que não é recomendável, no chão de fábrica, utilizar-se de pré-aquecimento, corrente pulsada e fazer estudos aprofundados quanto a influência do tecimento levando-se em conta que essas variáveis não afetaram prejudicialmente a microestrutura e resistência da junta e qualquer disposição em contrário encareceria desnecessariamente o processo. / Abstract: The objective of this work is to analyze the reality scientifically found in the ground of factory of a manufacturing company of agricultural equipments compared to the cares theoretically requested in the robotic GMAW e Pulsed of two dissimilar steels, the ABNT LN28 steel and a low alloy steel, the SAE 8620 steel. It is recommended of the literature that in the welding of the steel SAE 8620 the preheating is used, in that way it will be analyzed the influence of the preheating temperature and of the torch weaving movement in the microstructure and in the resistance of the welded joint. For that objective they will be soldiers several test specimens under different preheating temperatures and weaving movements conditions. In the analysis of the resulting microstructure will be considered the heating affected zone composed by the material SAE 8620 and the melted area and the resistance the traction of the welded joint obtained in the process. We will conclude that it is not advisable, in the factory ground, to use of preheating, pulsed current and to do deepened studies as the influence of the torch weaving movement, being considered that those variables didn't affect the microstructure and resistance of the welded joint prejudicially and any disposition in opposite would endear the process unnecessarily. / Mestre

This study develops a method to simulate a full-scale inertia friction weld with a sub-scale specimen and modifies a direct drive friction stir welder to perform the welding process. A torque meter is fabricated for the FSW machine to measure weld torque. Machine controls are modified to enable a force control during the IFW process. An equation is created to measure weld upset due to deflection of the FSW machine. Data obtained from a full-scale inertia friction weld are altered to account for the geometrical differences between the sub-scale and full-scale specimens. The IFW are simulated with the sub-scale specimen while controlling spindle RPM and matching weld power or weld RPM. The force used to perform friction welding is scaled to different values accounting for specimen size to determine the effects on output parameters including: HAZ, upset, RPM, torque, power and energy of the weld. Increasing force has positive effects to upset, torque, power and energy of the welds, while reducing the size of the HAZ.

[Abstract]: This thesis investigates the feasibility of closing wounds in skin tissue by laser welding as a substitute for suturing. Such a process would provide advantages in some surgical procedures. The investigation revised available theory on the action of lasers on skin tissue as a basis for the experimental program. The results of experiments using rat skin are then reported. In addition a thorough investigation of the normal (uninjured) tensile strength of rat skin was undertaken to provide a base line comparison. Laser systems permit very high-energy radiation of a single wavelength to be focused on a tiny spot, and have found application in many areas of engineering. They are also currently used in many branches of medicine including ophthalmology, gynaecology, dermatology, otolaryngology, and gastroenterology. These medical applications employ argon, YAG, and carbon dioxide type lasers. In many cases, lasers have been found to be more effective than conventional treatment methods with advantages including reduced blood loss, more accurate removal of unwanted tissue, shorter operating times and less postoperative pain and care (Gibson and Kernohan, 1993). Tissue welding using laser energy represents a small but growing area of medical research and is largely focused on anastomosis. This thesis investigates, using a specific experimental program, the feasibility of the bipolar contact Nd:YAG laser to weld cutaneous tissue. No similar published research has been identified in this area. The available literature focuses on non-contact lasers of various types and settings and mainly in the area of anastomosis. The experimental methodology and the specific technique for the bipolar contact laser is developed, tested and evaluated as part of this project. The welding techniques developed in this project overcome the previous difficulties of tissue alignment. The use of the bipolar laser probes substantially improves the ability to align the tissue edges to be joined. The probes give tactile feedback to the user and the pressure effect of the probes may assist with the welding process. The developed technique was no faster or easier than suturing. Viable welds and a useable technique for welding skin on rats were developed and tested. The resultant healing was comparable with published literature and both sutured and welded wounds returned to full strength as compared with the baseline data collected. All wounds had returned to full strength within 91 days. At 75 days there was not significant difference between laser welded and sutured wounds and they had achieved approximately 90 percent of full strength. Time to half strength was approximately 42 days and there was a larger standard deviation for both laser welded and sutured wounds. The most significant increase in strength and therefore healing occurred in the first 42 days. Simhon et al, 2001 states that a tensile strength of 0.6 N plus/minus 0.4 N was sufficient to hold tissue together. By day 7 the strength of the wound (laser welded) was more than twice the strength needed to maintain closure. There may have been sufficient healing for this to occur earlier but there were insufficient animals to allow for testing of this theory. In conclusion this experimental program and investigation has reviewed the available literature on the current use of lasers in medicine and their specific laser-tissue interaction which leads to tissue welding. It has provided a large database of tensile strength measurements collected with a reproducible methodology and reported in a standardised format. The developed technique for laser tissue welding using a bipolar contact Nd:YAG laser has been established and verified. It produces viable welds comparable in strength and healing rates to sutures.

"May 2002" / Includes bibliographical references (leaves 210-229) / xxvi, 368 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 2003

Thesis (Ph. D.)--Oregon Graduate Center, 1988.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 70-74). Also available in electronic version.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 109-116).