137 research outputs found

    Evolutionary Algorithms in Engineering Design Optimization

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    Evolutionary algorithms (EAs) are population-based global optimizers, which, due to their characteristics, have allowed us to solve, in a straightforward way, many real world optimization problems in the last three decades, particularly in engineering fields. Their main advantages are the following: they do not require any requisite to the objective/fitness evaluation function (continuity, derivability, convexity, etc.); they are not limited by the appearance of discrete and/or mixed variables or by the requirement of uncertainty quantification in the search. Moreover, they can deal with more than one objective function simultaneously through the use of evolutionary multi-objective optimization algorithms. This set of advantages, and the continuously increased computing capability of modern computers, has enhanced their application in research and industry. From the application point of view, in this Special Issue, all engineering fields are welcomed, such as aerospace and aeronautical, biomedical, civil, chemical and materials science, electronic and telecommunications, energy and electrical, manufacturing, logistics and transportation, mechanical, naval architecture, reliability, robotics, structural, etc. Within the EA field, the integration of innovative and improvement aspects in the algorithms for solving real world engineering design problems, in the abovementioned application fields, are welcomed and encouraged, such as the following: parallel EAs, surrogate modelling, hybridization with other optimization techniques, multi-objective and many-objective optimization, etc

    Kitchen robot prod. line development. Proj. of Bowden cables cutting and thermal forming machine.

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    This document presents particular description of work done during student’s internship in PR Metal company realized as ERASMUS PROJECT at ISEP. All information including company’s description and its structure, overview of the problems and analyzed cases, all stages of projects from concept to conclusion can be found here. Description of work done during the internship is divided here into two pieces. First part concerns one activities of the company which is robotic chefs (kitchen robot) production line. Work, that was done for development of this line involved several tasks, among them: creating a single-worker montage station for screwing robots housing’s parts, improve security system for laser welding chamber, what particularly consists in designing automatically closing door system with special surface, that protects against destructive action of laser beam, test station for examination of durability of heating connectors, solving problem with rotors vibrations. Second part tells about main task, realized in second half of internship and stands a complete description of machine development and design. The machine is a part of car handle latch cable production line and its tasks are: cutting cable to required length and hot-forming plastic cover for further assembly needs

    Multiphase flows in polymer microfluidic systems

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    Continuous delivery of segmented reagents using pressure-driven multiphase flow in microchannels is a promising technology for high throughput microfluidic bioassays. Separation and encapsulation of the target reagents with another inert fluid provide many advantages over single phase flow in microfluidic applications of biotechnology. In order to achieve these advantages and control these multiphase flows, it is necessary to understand their generation and transport characteristics as influenced by geometrical miniaturization, channel wall properties, the effects of surfactants and operating conditions. For gas-liquid two-phase flow, dry air and deionized water were driven into hot embossed PMMA microchannels with 200 μm square test microchannels. Flow regimes, flow maps and the lengths of the gas bubbles and liquid plugs in terms of the liquid volumetric flow ratio (βL) were determined. Continuous generation of regular segmented flow was also discussed. Three sub-regimes of the Segmented flow were identified based on the statistical phase length scales observed over a substantial test channel length. For the liquid-liquid segmented flow, deionized water and perfluorocarbon with a surfactant were used as test fluids in the hot embossed polycarbonate microchannels. The effects of three expansion ratios from the injection to the test channels of 2, 4, and 16 were investigated comparing the flow regimes, transitions and maps in terms of a fixed carrier fluid volumetric flow ratio. The length of the dispersed fluids and the distance between consecutive droplets or plugs in terms of the carrier fluid volumetric flow ratio (βC) were determined. Velocities of the dispersed droplets and plugs were measured using double-pulsed laser illumination and were found to be 1.46 ± 0.08 and 1.25 ± 0.05 times faster than the superficial velocity of the segmented flow, respectively. The multiphase flow pressure drops were measured for all of the flow regimes in gas-liquid two-phase and liquid-liquid segmented flows. Each flow regime identified on the basis of topological observations, including the length scale of each fluid phase and the number of the gas bubbles or dispersed droplets in unit length with respect to the volumetric flow ratio, was associated with different trends in the pressure drop variation

    Aplicabilidade industrial de estampagem incremental: análise funcional e energética

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    Doutoramento em Engenharia MecânicaIncremental sheet forming processes like single point incremental forming have been majorly studied since the beginning of the 2000's. Besides the applications in the prototyping eld, ISF processes can also be used to the manufacture of unique parts and small batches. This possibility has a great potential for speed up new product development and to make products in smaller series economically viable. Also, this capability leads to a new business possibilities, enable the development of exclusive or custom products. However, mainly due to its novelty, SPIF industrial operation is still very apprehensive with just a few examples of application. The main purpose of the present work is to create tools that can be used for the SPIF process management and present examples of usage in di erent industrial elds. The SPIF process is studied using the SPIF-A machine design and built at the Department of Mechanical Engineering at the University of Aveiro. Despite being a free form manufacture process, SPIF has some geometric limitations, manly due to the forming mechanics and formability limit of the materials. The possible part con gurations and the design orientation are settled, allowing a suitable part development. The hardware to perform incremental forming operations is outlined and the forming process is described, presenting alternative solutions both based on experimental work and state of the art review. A group of parts are developed and manufactured using SPIF as examples of industrial application. Parts are developed and evaluated to meet design and development requirements. New applications using SPIF as a rapid tooling process, typically exclusive form additive manufacturing technologies, are developed. The parity between SPIF and AM processes encounter industrial applications not only in prototyping or part manufacturing but also in tool development and fabrication. This novelty allows to decrease the time to market, decrease tooling cost and increase tooling complexity and consequential part design freedom in sheet metal moulds. The concept is developed and proof for a variety of thermoplastic and composite materials processing technologies.Os processos de estampagem incremental de chapa, como a estampagem incremental por ponto unico, t^em sido estudados em profundidade desde o in cio dos anos 2000. Para al em da aplica c~ao no desenvolvimento de prot otipos, os processo de estampagem incremental apresentam potencial de aplica c~ao no fabrico de produto unicos ou pequenos lotes. Esta possibilidade oferece vantagens ao permitir acelerar o processo de design e desenvolvimento de produto e ao tornar economicamente vi avel a produ c~ao de pequenas s eries. Para al em disso, esta possibilidade permite a cria c~ao de novas tipologias de neg ocio, possibilitando o desenvolvimento e fabrico de produtos exclusivos ou customizados. No entanto, principalmente devido a novidade do processo, a estampagem incremental ainda n~ao tem muitos exemplos de aplica c~ao em empresas. O principal objetivo do trabalho apresentado e desenvolver ferramentas que possam ser utilizadas para a industrializa c~ao do processo de estampagem incremental por ponto unico e apresentar exemplos de aplica c~oes em diferentes areas industriais. A m aquina SPIF-A desenvolvida no Departamento de Engenharia Mec^anica da Universidade de Aveiro e utilizada para o estudo do processo de estampagem incremental. Apesar do potencial do processo de estampagem para fabricar superf cies de forma livre, existem algumas limita c~oes. Estas devem-se maioritariamente ao comportamento do material e ao processo e par^ametros de estampagem. S~ao de nidas linhas orientadoras para o design de pe cas, bem como as poss veis con gura c~oes, de forma a possibilitar o desenvolvimento de pe cas fact veis. O equipamento necess ario para a realiza c~ao de trabalhos de estampagem incremental e os par^ametros de trabalho s~ao estudados com recurso a an alise de estado da arte e a trabalho experimental. Como exemplo de aplica c~ao industrial da estampagem incremental, s~ao desenvolvidas e fabricadas pe cas. Os produtos s~ao desenvolvidos e avaliados de forma a garantir o cumprimento dos requisitos de nidos. S~ao propostas novas aplica c~oes para a utiliza c~ao de estampagem incremental para o fabrico r apido de ferramentas, tipicamente exclusivo do processos de fabrico aditivo. A analogia entre a estampagem incremental e o fabrico aditivo permite encontrar aplica c~oes industriais para al em da prototipagem, com grande potencial para o desenvolvimento e fabrico de ferramentas. Esta novidade contribui para a redu c~ao do tempo de comercializa c~ao, reduzindo custos e permitindo uma maior exibilidade do desenho de um produto. O conceito de fabrico de moldes em chapa para diversos materiais termopl asticos e comp ositos e desenvolvido e analisado.Les processus de formage incr emental de t^ole, come formage incr emental un point, sont etudi es en profondeur d es le d ebut des ann ees 2000. Les processus ont son application dans le d eveloppement des prototypes et pr esentent aussi du vrai potentiel dans la fabrication des produits uniques et dans des petits lots. Cette possibilit e o re des avantages parce que permit d'acc el erer le processus de design et d eveloppement de produit et de faire le projet des petites s eries economiquement viables. En plus, formage incr emental possibilit e la cr eation des nouvelles typologies de a aires a cause de ca contribution dans la fabrication des produits personnalis es et exclusives. Malgr e ca et comme celui est un processus tr es r ecent, pour l'instant, le formage incr emental n'a pas beaucoup de utilisation industrielle. L'objectif principal du travail pr esent e est de d evelopper des moyens que peut ^etre utilis es pour auxili e l'industrialisation do processus de formage incr emental un point et pr esenter des exemples pour des distinctes applications industrielles. La machine SPIF-A d evelopp e dans le D epartement de Ing enierie M ecanique de l'Universit e d'Aveiro est utilis ee pour l' etude du processus de formage incr emental. Nonobstant le potentiel du processus de formage incr emental pour fabriquer des surfaces de forme libre il y a quelques limitations g eom etriques. C a d epend du comportement du mat eriel et les param etres de travail. Les con gurations g eom etriques possibles et les lignes directrices de conception sont d e nies de fa con a possibilit e le dessein des pi eces faisables. L'Equipment n ecessaire pour la r ealisation des travaux de formage incr ementa et les param etres de travail sont etudi es en utilisant l'analyse de l' etat de l'art et des travaux exp erimentaux. Comme exemple des applications industrielles du formage incr emental, sont d evelopp ees et fabriqu es des pi eces. Les produits sont d evelopp es et avalis es de fa con a assurer qu'il respecte les exigences d e nis

    7th Annual Focus on Creative Inquiry Poster Forum Program

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    The poster forum today displays a few of the more than 400 projects initiated by Clemson University Creative Inquiry teams. What is Creative Inquiry? It is small-group learning for all students. It is the imaginative combination of engaged learning and undergraduate research. Ultimately, it is the creation of an Ah-ha! Moment — and it is unique to Clemson University. Creative Inquiry establishes small teams of undergraduate students that work with faculty mentors to take on problems that spring from their own curiosity, from a professor’s challenge, or from the pressing needs of the world around them. Students take ownership of their projects. They ask questions, they take risks, and they get answers

    Craniofacial Growth Series Volume 56

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    https://deepblue.lib.umich.edu/bitstream/2027.42/153991/1/56th volume CF growth series FINAL 02262020.pdfDescription of 56th volume CF growth series FINAL 02262020.pdf : Proceedings of the 46th Annual Moyers Symposium and 44th Moyers Presymposiu

    Development, modelling and analysis of Vacuum Assisted Multipoint Moulding for manufacturing fibre-reinforced plastic composites

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    Full version: Access restricted permanently due to 3rd party copyright restrictions. Restriction set on 12.11.2019 by SE, Doctoral CollegeMultipoint tooling is a mould making technology that enables the rapid reconfiguration of a mould to create individual components. It replaces the commonly used, elaborately designed, and costly manufactured solid die, with an array of individually adjustable pins. These pins can be set to represent a large variety of freeform surfaces. An elastic interpolation layer (IPL) is used to smoothen the pin array and forms the actual tooling surface. This technology is well established in sheet metal forming and other areas of manufacturing. However, only little research has been conducted in the area of fibre-reinforced plastic composites. In this thesis, a novel multipoint tooling technology is introduced, that is specifically designed for fibre-reinforced plastic (FRP) manufacturing. Different to existing solutions, this Vacuum Assisted Multipoint Moulding (VAMM) is capable of creating concave and convex geometries on a single sided mould. This enables the use of established FRP manufacturing processes without further adaptation. Two iterations of this technology are developed: A manually adjusted small-scale test bench is used to validate the VAMM concept and conduct experiments on, and a fully automated full scale manufacturing prototype then is used to demonstrate the feasibility of the technology for an industrial application. The elasticity of the IPL introduces two system immanent dimensional defects: the overall shape deviates due to the deformation of the IPL and the punctual support of the interpolation layer leads to a golf-ball-like surface effect. A process model was created to predict behaviour of the VAMM tool and the interpolation layer, and estimate the expected part quality. An iterative shape control algorithm was implemented, to improve the dimensional accuracy of the manufacturing process, by readjusting individual pins in the tool. On this model, a sensitivity analysis was conducted to quantify the influence of the process and pin array parameters on the dimpling of the tool surface. The most important parameters were identified and used in a Metamodel of Optimal Prognosis (MOP). This MOP enables the rapid estimation of the system behaviour. It was used to optimise the VAMM process and the interpolation layer in order to maximise the geometric part quality. With this method two IPL designs, one with a single, and one with two separate layers of silicone rubber, were evaluated. It turned out that the dual layer configuration can handle a 24 % higher process pressure, while using a 9 % thinner interpolation layer, to produce parts similar to the single layer configuration.Huber Kunststoff und Technik GmbHSGL Carbon SEPutzin Maschinenbau Gmb

    ANISOTROPIC MATERIAL BEHAVIOR OF 3D PRINTED FIBER COMPOSITES

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    Literature has shown that 3D printed composites may have highly anisotropic mechanical properties due to variation in microstructure as a result of filament deposition process. Laminate composite theory, which is already used for composite products, has been proposed as an effective method for quantifying these mechanical characteristics. Starting with the analysis of comparing the printing orientation of premanufactured carbon fiber reinforced filament, the mechanical properties of 3D printed objects were examined. The mechanical properties changed not only as a result of machine choice, but how the sample is oriented along the printing bed. The analysis continued with looking at the dynamic properties of 3D printed composites. Results showed that the direction of the extruded strands altered the modal frequencies even for a sample with the same geometry. With the direction of the extruded strands affecting the mechanical properties, the composition of these strands is also shown to affect the mechanical properties of 3D printed composites. For commercially available fiber reinforced filaments, it was found through microscopic analysis that the fiber content stated by the manufacturer is inaccurate. In order to apply Classical Laminate Composite Theory (CLCT) the fiber volume fraction and aspect ratio need to be known. This lead to the creation of custom filament with the desired fiber content and geometry. The Halpin-Tsai model was used to predict the mechanical behavior of short fiber reinforced composites. Finally, the mechanical properties of continuous fiber composites were examined. The continuous fiber samples showed that fiber orientation had an vast effect on mechanical properties. A well oriented composite notably outperformed other fiber orientations with a drastic drop in Young\u27s modulus even with slight misalignment in fiber direction, but also resulted in brittle responses which may not be preferable. CLCT is applied using the simulation software ansys workbench. The results showed considerable correlation for each orientation and can be an accurate predictor of mechanical characteristics for 3D printed continuous fiber composites

    Modeling and Programming Shape-Morphing Structured Media

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    Shape-morphing and self-propelled locomotion are examples of mechanical behaviors that can be "programmed" in structured media by designing geometric features at micro- and mesostructural length scales. This programmability is possible because the small-scale geometry often imposes local kinematic modes that are strongly favored over other deformations. In turn, global behaviors are influenced by local kinematic preferences over the extent of the structured medium and by the kinematic compatibility (or incompatibility) between neighboring regions of the domain. This considerably expands the design space for effective mechanical properties, since objects made of the same bulk material but with different internal geometry will generally display very different behaviors. This motivates pursuing a mechanistic understanding of the connection between small-scale geometry and global kinematic behaviors. This thesis addresses challenges pertaining to the modeling and design of structured media that undergo large deformations. The first part of the thesis focuses on the relation between micro- or mesoscale patterning and energetically favored modes of deformation. This is first discussed within the context of twisted bulk metallic glass ribbons whose edges display periodic undulations. The undulations cause twist concentrations in the narrower regions of the structural element, delaying the onset of material failure and permitting the design of structures whose deployment and compaction emerge from the ribbons' chirality. Following this discussion of a periodic system, we study sheets with non-uniform cut patterns that buckle out-of-plane. Motivated by computational challenges associated with the presence of geometric features at disparate length scales, we construct an effective continuum model for these non-periodic systems, allowing us to simulate their post-buckling behavior efficiently and with good accuracy. The second part of the thesis discusses ways to leverage the connection between micro/mesoscale geometry and energetically favorable local kinematics to create "programmable matter" that undergo prescribed shape changes or self-propelled locomotion when exposed to an environmental stimulus. We first demonstrate the capabilities of an inverse design method that automates the design of structured plates that morph into target 3D geometries over time-dependent actuation paths. Finally, we present devices made of 3D-printed liquid crystal elastomer (LCE) hinges that change shape and self-propel when heated.</p
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