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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.
51

Rozdělení a aplikace matic flexibilního prototypového nástroje / Matrix classification and aplication in a flexible prototyping tool

Rygl, Ondřej January 2014 (has links)
The price of the tools for making prototypes and small series of products, as well as the cost of additional changes in the tool are quite high and increase the price of the final product. A flexible tool provides an advantageous solution to create a wide variety of molds. In this thesis the area of flexible tooling is introduced. An experimental mechanism has been manufactured and tested. With the help of a methodical approach several solutions for a flexible tool design have been proposed. Based on the evaluation of all given criteria, the most suited version has been designed and manufactured. The tool has been tested and evaluated for the thermoforming process. Improvements and potential applications have been suggested. The results show that the flexible tool has some limitations but has a broad potential use in several applications.
52

Design and Analysis of a Modular River Current Energy Converter

Pradip Krishnaa Murugan (13149063) 25 July 2022 (has links)
<p>This thesis proposes the design and documents analysis for a Modular River Current Energy Converter (MRCEC) to improve the efficiency of hydrokinetic turbine power systems. The MRCEC can produce electricity from low-velocity river flow with increased energy affordability and availability. The MRCEC, for the scope of this thesis, consists of the hydroturbine and maintenance systems. The turbine in the MRCEC system is a cross-flow cycloidal turbine that yields a high power coefficient (0.515) through a novel pitch variance mechanism involving a 3D cam that adapts to varying river flow conditions to maximize operational efficiencies. The cycloidal turbine is a four-section three-blade turbine that uses a unique hydrofoil profile designed for the MRCEC. The cycloidal turbine is housed in a frame supported by a flotation system to harness energy from near-surface currents. The flotation system, in turn, is connected to the service dock which houses the mooring, debris blockage, and maintenance systems. The mooring system allows the MRCEC to be fixed at the working site while allowing for self-adjustment with varying river depths. The debris blockage system prevents debris carried by the river from interfering with an operational hydroturbine. The maintenance system enables the installation, operation, and maintenance functions by integrating a flipping mechanism to invert the turbine for transportation and maintenance purposes. Mechanisms of these systems are designed to appropriate standards, then simulated to validate functionality at all stages of installation, operation, and maintenance.</p>
53

Diseño de un molino para el mejoramiento de la producción de queso en el distrito de Santa Cruz - Cajamarca

Villalobos Sanchez, Paulo Cesar January 2023 (has links)
Teniendo presente que la actividad pecuaria y ganadera es una las actividades primarias de supervivencia de un gran número de la población de las zonas de menor de desarrollo de nuestra patria, y dentro de estas actividades, cabe destacar, donde la cadena láctea como principal actividad de las familias de la sierra y selva, en el año 2016 se tiene que casi el 65% de las unidades agropecuarias se forjan en la sierra, 19% en la selva y 17% en la costa, en actividades de cultivos de pastos, forrajes, producción de leche, crianza de animales y posteriormente transformación en quesos y derivados lácteos, considerada la última como la principal actividad económica rentable de la población rural. En ese orden de ideas, la presente investigación tiene el objetivo proncipal de diseñar un molino con ciertas características para la molienda del quesillo, ( producto de haber cortado la leche con cuajo, ya sea casero o producto industrializado que se usa como cortante), antes de ser prensado y convertirse en queso e incrementar volumenes de producción en el distrito y provincia de Santa Cruz, departamento de Cajamarca, y por ende mejorar el abastecimiento del mercado local y la economía de las productoras, siguiendo el procedimiento del diseño mecánico, permitiendo su desarrollo y crecimiento industrial. Este molino consta de ciertas partes como: el disco como pieza fundamental para moler, eje principal, poleas, fajas de transmisión y rodamientos por lo que se determinaron algunas cargas a las que se encuentran sometido. Una vez conocida el funcionamiento del molino tipo disco, para determinar la velocidad se utilizó la fórmula del movimiento parabólico para determinar el alcance máximo de una partícula de quesillo molido, asi mismo se calculó el torque y dar paso a la potencia para la selección de un motor adecuado. Para su diseño y su futura construcción se necesito de un software CAD/ CAE, para este caso Solidworks 2016. Finalmente se realizó una evaluación económica calculando el TIR y VAN para conocer la viabilidad del proyecto, teniendo una inversión de 2 987, 52 soles para su construcción. / The main activities in the mountain and jungle from Peru in 2016, 64% of the agricultural was developed in the mountains, 20% in the jungle and 16% on the coast , about pasture and forage cultivation , husbandry, milk production and then being cheeses and dairy products, it was the best economic activity of the rural population. Therefore, this research has the objetive of designing a quesillo’s shredder with some requirements, before being pressed. and become cheese to increase production volumes in the Santa cruz province, department of Cajamarca, then we need to improve the supply of the local market and the producer’s economy, we have followed the mechanical design procedure allowing its development and growth industry. Also the parts of the shredder are: the disc as a fundamental piece for milling, the mechanical shaft, pulleys, transmission belts and bearings, it was important to calculate some loads, power, angular velocity and choose the shredder structure correctly to make the cheese’s machine. We knew disk-type shredder how it works, so we used some formulas like a parabolic movement, it was used to calculate the speed and the maximum range of a cheese’s particle,also we calculated the torque and the power to select an electric motor. Finally, we needed a CAD / CAE software, for our case Solidworks 2016, then we made an economic evaluation (IRR and NPV) to know the project viability, having an investment of 2987, 52 soles for its construction.
54

Design of High-Performance, Dual-Motor Liquid-Cooled, Linear Series Elastic Actuators for a Self-Balancing Exoskeleton

Kendrick, John Thomas 16 May 2018 (has links)
As a valuable asset in human augmentation and medical rehabilitation, exoskeletons have become a major area for research and development. They have shown themselves to be effective tools for training and rehabilitation of individuals suffering from limited mobility. However, most exoskeletons are not capable of balancing without the assistance of crutches from the user. Leveraging technology and techniques developed for force controlled humanoid robots, a project was undertaken to develop a fully self-balancing, compliant lower-body robotic exoskeleton. Due to their many beneficial features, series elastic actuators were utilized to power the joints on the exoskeleton. This thesis details the development of four linear series elastic actuators (LSEA) as part of this project. All 12-degrees of freedom will be powered by one of these four LSEA's. Actuator requirements were developed by examining human gait data and three robot-walking simulations. These four walking scenarios were synthesized into one set of power requirements for actuator development. Using these requirements, analytical models were developed to perform component trade studies and predict the performance of the actuator. These actuators utilize high-efficacy components, parallel electric motors, and liquid cooling to attain high power-to-weight ratios, while maintaining a small lightweight design. These analyses and trade studies have resulted in the design of a dual-motor liquid-cooled actuator capable of producing a peak force 8500N with a maximum travel speed of 0.267m/s, and three different single-motor actuators capable of producing forces up to 2450N continuously, with a maximum travel speeds up to 0.767m/s. / Master of Science
55

Structural Design Inspired by the Multiscale Mechanics of the Lightweight and Energy Absorbent Cuttlebone

Lee, Edward Weng Wai 03 November 2023 (has links)
Cuttlebone, the endoskeleton of cuttlefish, offers an intriguing biological structural model for designing low-density cellular ceramics with high stiffness and damage tolerance. Cuttlebone is highly porous (porosity ~93%) and lightweight (density less than 20% of seawater), constructed mainly by brittle aragonite (95 wt%), but capable of sustaining hydrostatic water pressures over 20 atmospheres and exhibits energy dissipation capability under compression comparable to many metallic foams (~4.4 kJ/kg). Here we computationally investigate how such a remarkable mechanical efficiency is enabled by the multiscale structure of cuttlebone. Using the common cuttlefish, Sepia Officinalis, as a model system, we first conducted high-resolution synchrotron micro-computed tomography (µ-CT) and quantified the cuttlebone's multiscale geometry, including the 3D asymmetric shape of individual walls, the wall assembly patterns, and the long-range structural gradient of walls across the entire cuttlebone (ca. 40 chambers). The acquired 3D structural information enables systematic finite-element simulations, which further reveal the multiscale mechanical design of cuttlebone: at the wall level, wall asymmetry provides optimized energy dissipation while maintaining high structural stiffness; at the chamber level, variation of walls (number, pattern, and waviness amplitude) contributes to progressive damage; at the entire skeletal level, the gradient of chamber heights tailors the local mechanical anisotropy of the cuttlebone for reduced stress concentration. Our results provide integrated insights into understanding the cuttlebone's multiscale mechanical design and provide useful knowledge for the designs of lightweight cellular ceramics. Upon the prior curvature analysis of the cuttlebone walls, we discovered that the walls were primarily "saddle-shaped". Thus, the characterization of different curvatures, varying between flat, domed, saddled, or cylindrical surfaces, were explored. A mathematical model was utilized to generate multiple walls with different curvature characteristics. We observed the mechanical performance of these walls via finite-element analysis and formulated different techniques for designing effective ceramic structures through incorporation of curvature. / Master of Science / The cuttlefish is a marine species that instead of having an inflatable swim bladder like fish, is a mollusk capable of swimming by utilizing their skeleton, called the cuttlebone. The cuttlefish can freely traverse the waters by controlling the flow of water in and out of their brittle skeletons, changing their buoyancy. For this reason, the cuttlebone must be very porous yet strong to withstand the deep-water pressures, enticing an interest for closer observation of the structure which may be useful in engineering applications involving ceramic structures. In this study, we examined an actual cuttlebone structure to better visualize its features with high-resolution synchrotron micro-computed tomography (µ-CT) and tabulated its mechanical performance through a variety of tests using computational software. The skeletal design of the cuttlebone consists of multiple layered chambers supported by wavy, pillar-like walls. It was revealed that the cuttlebone is remarkable due to its multiscale design: the asymmetric geometry of the walls are designed to tolerate considerable amounts of energy while a stiff construction; at the chamber level, variation of walls (number, pattern, and waviness amplitude) helps avoid complete destruction of the structure in the event of an excessive force; at the entire skeletal level, various of chamber heights reduces inflicted stress in concentrated regions of the cuttlebone. The wavy walls were also observed to retain a saddle-shaped curviness, versus simple flat, domed, or cylindrical shaped walls. This created an incentive to explore the effects of curvature on the structural integrity of brittle ceramic structures. We developed an effective way for generating walls with different curvatures and observed the mechanical performance of each wall by crushing them in computer simulations. It was identified that adding curvature to brittle walls prolonged the failure period significantly. While the cylindrical walls were found to be rather stiff, saddle-shaped walls, although not capable of withstanding as much force as flat or cylindrical walls, has a more progressive failure behavior meanwhile maintaining high energy absorption, hence the saddled walls of the cuttlebone to allow maintenance and self-repair in damaged regions.
56

Driveline : Moving infantry target (MIT)

Hjortman, Robin, Harrysson, Kristian January 2016 (has links)
This report is part of a bachelor thesis implemented at Saab training systems AB in Huskvarna. It treats the concept development of the driveline on Moving infantry target, MIT. Today Saab has a problem in the shape of that their customers uses the wrong moment when tightening the cog belt of the driveline. As a consequence the cog belt has a high risk of snapping if it is too tight or pluck off if it is too loose. Thereto the electrical motors used in the MIT has gone out of production. The task boiled down to produce a number of proposals that improves the chucking or driveline solution together with finding a new electrical motor to replace the outdated one. A concept study was made containing detailed examinations together with Saab. To answer the problems questions, several product development methods were used, like Quality function deployment and Pugh’s matrix, to reach a final concept. The last concepts were modeled in a 3D-program for an easier comparison between their feasibility. The chosen solution consisted of two motors that via a gearing actuates the respective axle. By replacing the belt drive and choosing more lubrication free gears the maintenance is expected to be improved. In addition the product price is lowered by careful choices of components. The production of a prototype could not be implemented due to lack of time.
57

Ethics in structural design and mechanical design for live entertainment scenery

Vieira, David Vincent 21 October 2014 (has links)
Scenic construction requires a strong understanding of a range of principles related to construction including: materials strength properties, mechanical components, electrical motor systems, fluid power systems, and finishing techniques. A manager of scenic construction, or a Technical Director (TD), is required to take artistic designs and ideas and create magical elements on stage that are safe for performers, installers, operators, and audiences. In order to create these onstage spectacles, a great deal of planning, engineering, and careful fabrication must take place. There are several ways for a Technical Director to gain the knowledge required to effectively work at any level of entertainment production. This mixed-methods research study asks: what are the ethical standards that guide how a TD’s work is completed? The thesis begins with a review of the job of the Technical Director in Live Entertainment and data from a survey conducted of professionals in scenic technology. Results from the survey were analyzed to provide both quantitative data, in the form of statistics, and qualitative response data. Additional discussion addresses a sample of the resources for structural design support available currently to the field, as well as challenges that some professionals confront in their typical practice. The thesis concludes a review of literature around engineering ethics and liability in engineering practice and recommendations for the incorporation of new ethical standards in live entertainment scenic production. / text
58

Utveckling av en universell laddare / Development of a universal charger

Sahlberg, Mikael January 2007 (has links)
<p>Syftet med examensarbetet har varit att undersöka möjligheterna att utveckla, producera och lansera en ny universell laddare. Målet har varit att kunna ladda så många modeller av så många produkter som möjligt, vilket innefattar mobiltelefoner, kameror, datorer och MP3-spelare etc. Arbetet skulle leda fram till ett förslag på produkt.</p><p>Genom att undersöka befintliga patent och produkter, har marknaden granskats och slutsatsen är att det finns en uppsjö av universella laddare på marknaden. Dock finns det få produkter som inger säkerhet, möjliggör multipel laddning och som är stationära. Dessa egenskaper blev grundstenar i den kravspecifikation som utarbetades. Genom en teknisk analys och kundundersökning sammanställdes ytterligare viktiga parametrar.</p><p>Resultatet blev en stationär produkt som kan ladda både en bärbar dator och flera mindre elektroniska produkter. Genom att använda en metod som i rapporten betecknas tappteknik kan rätt laddningsförhållande garanteras. Med hjälp av en mikroprocessor och produktspecifika tappar eller ändadaptrar kan laddning av i princip alla sorters produkter och modeller ske.</p><p>Arbetet har även innefattat konstruktion, CAD och prototypframtagning.</p> / <p>The purpose with this thesis work has been to investigate the possibilities to develop, manufacture and introduce a new universal charger. The aim has been to be able to charge as many models of as many different products as possible, including cell phones, cameras, laptops, MP3-players etc. The work would lead to a product proposal.</p><p>By an examination of existing patents and products, has the market been reviewed. The conclusion is that there already are big amount of universal chargers in the international market. Yet there are only a few products that inspire safety, have a multiple charging function and which are for stationary use. Those properties became fundamentals in the specification. With a technical analyse and a customary review were more parameters included.</p><p>The result is a stationary product that can be used to charge both a laptop and several smaller electronic products. By using a method that is called tip technology can the right charging conditions be guaranteed. With a micro processor and with tips which are specific for each product can mostly all sorts of products and models be charged.</p><p>The work has also included mechanical design, CAD and the build of a prototype.</p>
59

Développement d'un procédé d'enroulement filamentaire adapté aux matériaux composites sandwichs et caractérisation mécanique des matériaux / Development of a filament winding process adapted to sandwich composite materials and mechanical characterization of materials

Haddad, Mohamed 23 October 2017 (has links)
Les matériaux composites, et en particulier les sandwichs, sont très étudiés depuis des décennies. En effet, l'alliance entre légèreté et résistance de ces structures entraîne le développement de leur utilisation. Leur méthode de fabrication et éventuellement leur caractérisation restent des points essentiels dans la plupart des études. Ce travail s’inscrit dans le projet FUI SOLLICITERN qui vise à développer une citerne routière en matériau composite sandwich pour un véhicule d’hydrocurage. Comme première étape, et à partir du principe de l’enroulement filamentaire classique, l’objectif consiste à chercher des conceptions qui sont les mieux adaptées à l’enroulement d’un matériau sandwich sur un mandrin cylindrique, tout en respectant les paramètres de l’enroulement et leur influence sur la structure et les propriétés. La solution optimale étant validée, les matériaux constitutifs ont été étudié en mesurant de nombreuses propriétés mécaniques. L’objectif est de pouvoir aider le bureau d’étude à valider une solution de fabrication et de vérifier que les propriétés sont celles attendues. Pour ce faire, des caractérisations statique et dynamique ont menée sur des échantillons incurvés fabriqués par le procédé optimisé pour notre application. Cette partie comporte notamment différents essais expérimentaux dans le but de valider le comportement de la structure visée avec les dimensions et les combinaisons de matériaux les plus appropriées, en tenant compte du processus de fabrication. La meilleure configuration structurelle est retenue à la fin pour la fabrication de la citerne routière prototype. / Composite materials, and especially sandwich structures, have been studied for decades. Indeed, the association between lightness and resistance of these structures leads to the development of their use. Their manufacturing method and their characterization remain as essential points in most studies. This work is part of the FUI SOLLICITERN project, which aims to design a composite water treatment tank for vehicles intended for this purpose. As a first step, and based on the classical filament winding principal, we aim to search designs that are best adapted to the fabrication of a curved sandwich material on a cylindrical mandrel, while respecting the process parameters of and their influence on structural properties. Since an optimal solution was validated, the constituent materials were studied by measuring mechanical properties. The objective is to help our industrial partner to validate a manufacturing solution and verify that such properties are the expected ones. For that, several static and dynamic characterizations were carried out on curved samples manufactured by the optimized process designed for our application. This part includes various experimental tests in order to validate the structure behavior with the most appropriate dimensions and material combinations, taking into account the manufacturing process. At the end, the best structural configuration is retained for the first tank prototype fabrication.
60

Maîtrise du processus de modélisation géométrique et physique en conception mécanique / Geometrical and physical modeling process control for mechanical design

Charpentier, Frédéric 06 June 2014 (has links)
La conception de produits a pour objectif de définir techniquement un produit en satisfaisant les besoins de l'ensemble des clients du cycle de vie du produit. Les enjeux industriels conduisent à développer des modèles et des outils d'aide à la conception afin de répondre aux besoins clients tout en optimisant le triptyque coût-qualité délais. L'objectif de cette thèse est de proposer une vision globale permettant d'appréhender les différents types de modélisation. Pour atteindre cet objectif, une analyse globale de ces notions est nécessaire afin d'obtenir une représentation commune du système pour les différentes activités de conception et de simulation. L'intérêt de cette approche est de pouvoir mettre en évidence les dépendances et les relations entre ces activités. Cette approche doit permettre d'appréhender les différents niveaux de détails (systémique) lors de la décomposition fonctionnelle et structurelle du produit. Elle doit également permettre de suivre l'élaboration des modèles physiques pour la simulation. Nous proposons une traçabilité du processus de conception et du processus de modélisation permettant de remettre en cause, le cas échéant, les choix de conception et les hypothèses de modélisation. Ce travail est fondé sur des concepts de GeoSpelling comme le " skin modèle ", les opérations et les propriétés. Ils sont enrichis d'autres concepts comme les modèles finis et infinis et les modèles primitif et de simulation. / Product design aims to technically define a product satisfying the needs of all customers during the product life cycle. Industrial issues lead to develop models and tools supporting design to meet customer needs and contributing to costs-quality-and time optimisation. The objective of this thesis is to propose an overall vision making it possible to apprehend the various types of modeling. To achieve this goal, a comprehensive analysis of these concepts is necessary in order to obtain a common representation of the system for the various activities of design and simulation. The advantage of this approach is to highlight the dependencies and relationships among those activities. This approach should allow to apprehend the various levels of detail (systemic) during the functional and structural decomposition activity. It should also enable to monitor the development of the physical models for the simulation. We propose a traceability of the design process and of the modeling process allowing to review as appropriate the design choices and the modeling assumptions. This work is based on concepts of GeoSpelling as the "skin model", the operations and the properties. They are complemented by other concepts as the finite and infinite models and the primitive and simulation models.

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