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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Design e tecnologia: manufatura aditiva por sinterização de poliestireno em equipamento de gravação e corte a laser / Design e technology: additive manufacturing by polystyrene sintering using a laser cutting and engraving machine

Ribeiro, Thiago Rafael Rodrigues January 2018 (has links)
A sinterização a laser (SL), uma das tecnologias de manufatura aditiva (MA), se mostra de grande interesse devido a uma série de características, mas, principalmente, devido a sua capacidade de processar uma ampla gama de materiais em pó, a qual amplia possibilidades de pesquisa e desenvolvimento no campo do Design. Neste trabalho, sob o prisma da MA, tem-se por objetivo realizar a sinterização a laser em um equipamento de gravação e corte a laser convencional, sem pré-aquecimento do material. No desenvolvimento do estudo, foi utilizado um equipamento galvanométrico a laser para a realização de experimentos de sinterização de poliestireno em pó (PS 200). Os ensaios de caracterização desse material polimérico amorfo, constataram o diâmetro médio dos grãos de 54,3 μm em formato irregular. Para viabilizar o processo proposto, investigaram-se os parâmetros de processo para a SL, valendo-se de um dispositivo de controle da altura da mesa de trabalho. A melhor amostra (geometria circular) foi construída com potência 20 W, velocidade de varredura de 200 m/min e distância entre linhas de varredura do feixe laser de 0,1 mm. Esse último parâmetro, é relacionado ao diâmetro do foco do feixe laser, o qual foi estimado pelos ensaios em 0,3 mm. Com isso, foi calculada a densidade de energia transferida para o material, conhecida como Número de Andrew (An), em 0,06 J/mm² Análises visuais, macroscópicas e microscópicas, antes e depois da sinterização de uma camada (2D) e de camadas empilhadas (3D), além de sua digitalização tridimensional, foram realizadas. As amostras apresentaram deformação no plano x-y (elipticidade), no eixo z (empenamento) e grande porosidade. Nos ensaios de empilhamento de camadas foi determinada, para os parâmetros utilizados, a espessura de camada de 0,15 mm. Posteriormente, foi construído um modelo 3D com 100 camadas, o qual apresentou um acabamento liso na maior parte de sua lateral, porém, foram observadas estrias verticais ao longo da sua altura, as quais foram consideradas como característica do processo (devido à inércia dos espelhos galvanométricos). Por fim, esses parâmetros foram validados em um ensaio valendo-se de uma forma orgânica (face humana) em escala 1:4. O fator crítico foi o empenamento, o qual prejudica a distribuição de novas camadas de pó, mas pôde ser contornado com espessuras de camada de alturas superiores a esse empenamento. Assim, considera-se que para a viabilização prática do processo de sinterização proposto, em equipamentos de corte e gravação a laser convencionais, torna-se importante o desenvolvimento de um dispositivo de distribuição de pó automatizado, o qual permitiria a construção de modelos 3D de maior tamanho e complexidade. / Laser sintering (SL), one of the additive manufacturing (MA) technologies, is of great interest due to a number of characteristics, but mainly due to its ability to process a wide range of powder materials, which offers possibilities for research and development in the Design’s field. In this work, under the prism of the MA, the goal is to perform laser sintering in a conventional laser engraving and cutting equipment, without preheating the material. In the development of the study, a galvanometric laser equipment was used to perform powder polystyrene (PS 200) sintering experiments. The characterization tests of this amorphous polymer material showed the average grain diameter of 54.3 μm in irregular shape. In order to make the proposed process feasible, the process parameters for the SL were investigated, using a device to control the height of the workbench. The best sample (circular geometry) was built with 20 W power, laser scan speed of 200 m/min and distance between scanned lines of 0.1 mm. This last parameter is related to the diameter of the laser beam waist, which was estimated by the tests in 0.3 mm Thus, the energy density transferred to the material, known as Andrew's Number (An), was calculated at 0.06 J/mm². Macroscopic and microscopic visual analysis, before and after the sintering of a two-dimensional layer (2D) and of stacked layers (3D), in addition to its 3D scanning, were performed. The samples displayed deformation in the x-y plane (ellipticity), at the z-axis (warpage) and high porosity. In the layer stacking tests, the layer thickness of 0.15 mm was determined for the parameters used. Next, a 3D model with 100 layers was sintered, which presented a smooth finish in most of its lateral, however, vertical streaks were observed along its height, which were considered as characteristic of the process (due to the inertia of the galvanometric mirrors). Finally, these parameters were validated in an assay using an organic form (human face) in a 1: 4 scale. The critical factor was the warpage, which impairs the distribution of new layers of powder, but could be worked around with layer thicknesses of heights higher than this warpage. Thus, it is considered that for the practical feasibility of the proposed sintering process in conventional laser cutting and engraving machine, it is important to develop an automated powder distribution device, which would allow the construction of greater size and complexity 3D models.
32

Optimalizace technologie laserového dělení trubek se čtvercovým průřezem / Optimization of the laser cutting technology of tubes with a square cross section

Podaný, Petr January 2018 (has links)
The master thesis deals with the design and manufacture of tabbed joint in the profile with a square cross section using laser cutting. They examine their suitability and impact on the following MAG welding operation in terms of efficiency and accuracy. The theoretical part provides basic information about lasers used in industry and laser cutting methods. There is also a section dedicated to laser apparatus for tube cutting along with problematic about the laser cutting profiles. The experimental part describes the procedure of designing tabbed joint, making samples and measuring them. In the end, the individual samples are compared in terms of angular deflection after welding. The thesis also contains a technical-economic evaluation, where the costs of individual operations are quantified.
33

Studium kvality řezu mezních tlouštěk oxidačního řezání v závislosti na průměru ohniskového spotu při laserovém dělení materiálu / Study cutting quality of flame cutting of limit thicknesses depending on the diameter of the focal spot during laser cutting of material

Maňas, Petr January 2016 (has links)
Experimental work evaluated the dependence of the thickness of the cutting edge, its roughness and assessment of appearance with regard to the defects resulting from the diameter of the focal spot during oxidative cutting Yb:YAG laser. Other variables include the experiment: process parameters such as laser power, cutting speed, oxygen pressure and focus position. Experiment is based on the Taguchi tables. Test samples were cut off from sheet thickness 10, 15 and 20 mm. Representatives of conventional steel were S235JRC+N, S235JR, S235JR+N and steel type RAEX developed for laser and plasma cutting. Samples were evaluated according to the ČSN EN ISO 9013. The evaluation of samples was into classes according to standards of quality. Hardness measurements were performed on the samples thickness 20 mm of convectional steel and steel type RAEX.
34

Optimalizace výroby součástky z konstrukční oceli tl. 20 mm technologií laserového dělení / Optimization of a part production made of a structural 20 mm thick steel using laser cutting technology

Šoukal, Hynek January 2017 (has links)
The thesis deals with the optimization of process parameters in the oxidative laser cutting of structural 20 mm thick steel with regard to the type of material, the resulting roughness of the cut and the resulting price of the product. In line with the literary study and the Taguchi method, an experiment was developed. The cutting speed, laser performance, cutting gas pressure, and focal position were controlled during the experiment. Sample sets were cut with 7.5" and 10" focusing lens from the TATA STEEL S355MC and SSAB LASER 355 MC steels. According to ČSN EN ISO 9013, the samples were evaluated for roughness. Then micro and macro structures were evaluated, and compare the hardness according to Vickers. In conclusion, technical and economic evaluation was determined.
35

Hybrids

Randestad, Stina January 2022 (has links)
Juxtaposing in art and design is a commonly used method of creating something new by recomposing already existing elements. The hybrid outcome allows the spectator to re-evaluate the elements merged, and the new relationship set up between them. Hybrids is an attempt to find such meetings through investigating possible material combinations through a series of fabric manipulating techniques, with the aim to generate volume and expression. Parts of the development, with emphasis on print making, have been conducted in a generative methodological way, using randomization and the computer as an autonomous co-creator. Two fabric manipulating techniques were developed during the course of the work; laser cutting mesh and combining stretchy with stiff materials. The common feature of these techniques is their ability to transform from 2D to 3D. Hybrids questions the hierarchy of the traditional fashion design process where form dictates the choice of material. Instead, material comes first, while form relating to body follows. The result is expressive and bold, positioning itself at the intersection of fashion and textile design.
36

Modeling Of Steel Laser Cutting Process Using Finite Element, Machine Learning, And Kinetic Monte Carlo Methods

Dillon Anthony Stangeland (12469389) 12 July 2022 (has links)
<p>Laser cutting is a manufacturing technology that uses a focused laser beam to melt,burn and vaporize materials, resulting in a high-quality cut edge. Although previous efforts are primarily based on a trial-and-error approach, there is insufficient understanding of the laser cutting process, thus hindering further development of the technology. Therefore, the motivation of this thesis is to address this research need by developing a series of models tounderstand the thermal and microstructure evolution in the process.</p> <p>The goal of the thesis is to design a tool for optimizing the steel laser cutting processthrough a modeling approach. The goal will be achieved through three interrelated objec-tives: (1) understand the thermal field in the laser cutting process of ASTM A36 steel using the finite element (FE) method coupled with the user-defined Moving Heat Source package;(2) apply machine learning method to predict heat-affected zone (HAZ) and kerf, the keyfeatures in the laser cutting process; and (3) employ kinetic Monte Carlo (kMC) simulationto simulate the resultant microstructures in the laser cutting process.</p> <p>Specifically, in the finite element model, a laser beam was applied to the model with the parameters of the laser’s power, cut speed, and focal diameter being tested. After receiving results generated by the finite element model, they were then used by two machine learning algorithms to predict the HAZ distance and kerf width that is produced due to the laser cutting process. The two machine learning algorithms tested were a neural network and asupport vector machine. Finally, the thermal field was imported into the kMC model as the boundary conditions to predict grain evolution’s in the metals.</p> <p>The results of the research showed that by increasing the focal diameter of a laser, the kerf width can be decreased and the HAZ distance experienced a large decrease. Additionally, apulse-like pattern was observed in the kerf width through modeling and can be minimized into more of a uniform cut through the increase of the focal diameter. By increasing thepower of a laser, the HAZ distance, kerf width, and region of the material above its original temperature increase. Additionally, through the increase of the cut speed, the HAZ distance, kerf width, kerf pulse-like pattern, and region of the material above its original temperature decrease.</p> <p>Through the incorporation of machine learning algorithms, it was found that they can be used to effectively predict the HAZ distance to a certain degree. The Neural Networkand Support Vector Machine models both show that the experimental HAZ distance datalines up with the results derived from ANSYS. The Gaussian Process Regression HAZ model shows that the algorithm is not powerful enough to create an accurate prediction. Additionally, all of the kerf width models show that the experimental data is being overfit by the ANSYS results. As such, the kerf width results from ANSYS need additional validation to prove their accuracy.</p> <p>Using the kMC model to examine the microstructure change due to the laser cutting process, three observations were made. First, the largest grain growth occurs at the edge ofthe laser where the material was not hot enough to be cut. Then, grain growth decays as thedistance from the edge increases. Finally, at the edge of the HAZ boundary, grain growth does not occur.</p>
37

Uso de usinagem por jato de água, usinagem por controle numérico computadorizado e corte a laser no design de superfícies tácteis a partir de padrões modulares encaixáveis em ágata e cedro

Silveira, Flávia Lopes da January 2011 (has links)
Este trabalho tem por objetivo o design e a fabricação de superfícies tácteis a partir de padrões modulares encaixáveis. Estas superfícies foram construídas em diferentes materiais naturais (minerais e madeiras) e em distintos processos de fabricação inovadores (usinagem por jato de água, usinagem por controle numérico computadorizado ou CNC e corte a laser). A intenção foi desenvolver uma metodologia de design & tecnologia para aplicá-la em painéis de revestimento que possam ser produzidos em baixa escala de forma semi-industrial. A grande variedade de materiais naturais encontrados no estado do Rio Grande do Sul; a carência de design associado a estes materiais quando do produto final e o volume de rejeitos oriundos deste beneficiamento, foram os principais motivadores para a utilização destas matérias primas. O estudo de diferentes técnicas de design de superfície auxilia na transformação destes materiais, para que os mesmos passem a ter o formato de módulo. Dentro deste contexto, foram estudadas as técnicas desenvolvidas pelo artista Maurits Cornelis Escher. Ele dedicou boa parte de sua vida profissional à composição de desenhos que, justamente, partem da utilização da simetria, modularidade, continuidade e encaixe. Neste sentido, após a compreensão das técnicas utilizadas por Escher, alguns de seus desenhos foram aplicados nos materiais selecionados através dos processos de fabricação adequados, possibilitando a construção das diferentes superfícies tácteis. Os resultados obtidos identificam que a utilização de processos de fabricação inovadores para interferência nos materiais naturais são ferramentas importantes para a promoção de uma nova geração de produtos locais. Conclui-se que estas interferências viabilizam a fabricação de produtos com maior valor estético, social e econômico. / This work aims at the design and the manufacturing of tactile surfaces from modular plug patterns. These surfaces were built in different natural materials (mineral and wood) and in distinct innovative manufacturing processes (waterjet machining, computerized numerical control machining or CNC and laser cutting). The objective was to develop a design & technology methodology for applying it in coating panels that can be produced on a semiindustrial small scale. The huge variety of natural materials found in Rio Grande do Sul State, the lack of design associated to these materials as to the final product and the volume of waste from this processing were the main motivators for the use of these raw materials. The study of these different techniques of surface design helps the transformation of these materials in order that they start to have the modular format. Within this context, the techniques developed by the artist Maurits Cornelis Escher were studied. He devoted much of his professional life to the composition of drawings beginning exactly with the use of symmetry, modularity continuity and joint. In this sense, after understanding the techniques used by Escher, some of his drawings were applied in the materials selected through suitable manufacturing processes, enabling the construction of different tactile surfaces. The results obtained identify that the utilization of innovative manufacturing processes to interfere in the natural materials are important tools for the promotion of a new generation of local products. It is conclude that these interferences enable the manufacture of products with greater aesthetic, social and economic value.
38

Business Case - Implementation of Laser Technologies at Scania Ferruform : Welding- and cutting applications for the manufacturing of banjo parts

Hedemalm, Markus, Hallsten, Zebastian January 2018 (has links)
Scania Ferruform AB is an independent affiliate of the truck- and bus manufacturer Scania AB which produces rear axle housings among other chassis components for said vehicles. The banjo part, i.e. the base of the rear axle housings undergoes processes which have issues both in terms of exceeded technical life span and insufficient production capacity. These three processes consist of both milling and welding operations. In order to resolve these issues the discussion of future investments arise. As this is discussed, the question whether alternative technologies could be of interest, specifically the performance of welding- and cutting operations with the use of laser technologies. By reviewing state-of-the-art literature, studying the present production conditions and interviewing experts within academia as well as parties active in developing and supplying industrial laser systems it has been shown that a laser arc hybrid welding technique would be the most suitable replacement, while laser nitrogen cutting would be the most suitable cutting technique. This project presents the theoretical outcome of implementing laser arc hybrid welding as a replacement to the present and conventional gas metal arc welding, as well as the possibility of using laser nitrogen cutting as a replacement to a set of milling processes. The study has shown that by implementing these technologies in a manner which also alters the balance in performed operations achieves a cycle time below the future goal for each production section. Cycle time values, quantities and costs are expressed with an indexed value of t, n and k respectively due to confidentiality. The first investment scenario results in an annual saving of consumption costs by 4 738k SEK, with a total investment cost of 112 743k SEK and 6,9 years pay-off time. The second scenario results in an annual saving of consumption costs by 5 018k SEK, with a total investment cost of 114 843k SEK and 5,2 years pay-off time. The third scenario is similar to the second in terms of the manufacturing processes, but it is the alternative of the lowest investment cost. This scenario would result in the same sum of annual savings as the second scenario, but with an investment cost of 89 843k SEK and 0,2 years pay-off time.
39

Tourist : An investigation of the printed Hawaii shirt / Turist : En undersökning av den mönstrade Hawaiiskjortan

Sjögren, Linn January 2018 (has links)
The aim of this work is to explore the printed Hawaii shirt through material investigations in search of new print meetings. A vital step for this investigation was to develop the classic Hawaii- prints and motives in mixed media. Followed by exploring alternative printing techniques such as transfer printing, laser cutting and knitting in different materials to reach new expressions yet keeping a clear reference to the Hawaii shirt. The intention of this work was to investigate how the Hawaii shirt with its classic print could interact with the mind and body of the wearer. Furthermore, to question the informal rules of wearing a Hawaii shirt with a starting point in Umberto Eco’s theories about epidemic self-awareness. The motive of this work is to critically look at the society today, with a focus on consumerism, foreign travel and tourism and the expression of it, with the Hawaii shirt as a symbol of these things. Based on the assumption of the Hawaii shirt being a tacky souvenir that tourists bring back home from their holidays. This work show new expressions of the printed Hawaii shirt through innovative print meetings. This work also proposes alternative ways of wearing a Hawaii Shirt.
40

Uso de usinagem por jato de água, usinagem por controle numérico computadorizado e corte a laser no design de superfícies tácteis a partir de padrões modulares encaixáveis em ágata e cedro

Silveira, Flávia Lopes da January 2011 (has links)
Este trabalho tem por objetivo o design e a fabricação de superfícies tácteis a partir de padrões modulares encaixáveis. Estas superfícies foram construídas em diferentes materiais naturais (minerais e madeiras) e em distintos processos de fabricação inovadores (usinagem por jato de água, usinagem por controle numérico computadorizado ou CNC e corte a laser). A intenção foi desenvolver uma metodologia de design & tecnologia para aplicá-la em painéis de revestimento que possam ser produzidos em baixa escala de forma semi-industrial. A grande variedade de materiais naturais encontrados no estado do Rio Grande do Sul; a carência de design associado a estes materiais quando do produto final e o volume de rejeitos oriundos deste beneficiamento, foram os principais motivadores para a utilização destas matérias primas. O estudo de diferentes técnicas de design de superfície auxilia na transformação destes materiais, para que os mesmos passem a ter o formato de módulo. Dentro deste contexto, foram estudadas as técnicas desenvolvidas pelo artista Maurits Cornelis Escher. Ele dedicou boa parte de sua vida profissional à composição de desenhos que, justamente, partem da utilização da simetria, modularidade, continuidade e encaixe. Neste sentido, após a compreensão das técnicas utilizadas por Escher, alguns de seus desenhos foram aplicados nos materiais selecionados através dos processos de fabricação adequados, possibilitando a construção das diferentes superfícies tácteis. Os resultados obtidos identificam que a utilização de processos de fabricação inovadores para interferência nos materiais naturais são ferramentas importantes para a promoção de uma nova geração de produtos locais. Conclui-se que estas interferências viabilizam a fabricação de produtos com maior valor estético, social e econômico. / This work aims at the design and the manufacturing of tactile surfaces from modular plug patterns. These surfaces were built in different natural materials (mineral and wood) and in distinct innovative manufacturing processes (waterjet machining, computerized numerical control machining or CNC and laser cutting). The objective was to develop a design & technology methodology for applying it in coating panels that can be produced on a semiindustrial small scale. The huge variety of natural materials found in Rio Grande do Sul State, the lack of design associated to these materials as to the final product and the volume of waste from this processing were the main motivators for the use of these raw materials. The study of these different techniques of surface design helps the transformation of these materials in order that they start to have the modular format. Within this context, the techniques developed by the artist Maurits Cornelis Escher were studied. He devoted much of his professional life to the composition of drawings beginning exactly with the use of symmetry, modularity continuity and joint. In this sense, after understanding the techniques used by Escher, some of his drawings were applied in the materials selected through suitable manufacturing processes, enabling the construction of different tactile surfaces. The results obtained identify that the utilization of innovative manufacturing processes to interfere in the natural materials are important tools for the promotion of a new generation of local products. It is conclude that these interferences enable the manufacture of products with greater aesthetic, social and economic value.

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