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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.
1

Stratégie multiparamétrique et métamodèles pour l'optimisation multiniveaux de structures / Multilevel optimisation of structures using a multiparametric strategy and metamodels

Laurent, Luc 02 December 2013 (has links)
Bien que de plus en plus employée au sein des bureaux d'études dans le cadre de la conception mécanique, l'optimisation reste à l'heure actuelle encore relativement peu utilisée dans le cadre des assemblages de structures. La résolution mécanique de ce type de problèmes nécessite la mise en oeuvre de méthodes numériques de résolution capables de prendre en compte des non-linéarités de type frottement et contact. Ces méthodes sont, en raison du temps de calcul, généralement incompatibles avec la recherche d'un optimum global nécessitant un nombre important de résolutions. C'est pour pallier à ce problème que ce travail propose l'emploi d'une approche d'optimisation bi-niveaux de modèles faisant intervenir deux outils: (1) la stratégie multiparamétrique, basée sur la méthode LaTIn, assure d'importantes réductions des temps de calcul associés aux multiples résolutions du problème mécanique et (2) un métamodèle de type cokrigeage construit à partir d'un nombre limité de réponses et gradients calculés par le solveur mécanique. Ce métamodèle est alors capable de fournir à coût extrêmement faible des réponses approchées de la fonction objectif. Une optimisation globale est ensuite réalisée sur ce dernier, assurant l'obtention d'un optimum global. Le métamodèle de cokrigeage est étudié en détail sur des exemples analytiques et mécaniques comportant divers nombres de paramètres. Par ailleurs, une étude complète de l'emploi de la stratégie multiparamétrique est proposée et de nombreux exemples d'assemblages sont considérés, permettant ainsi d'illustrer les performances significatives de la procédure d'optimisation proposée. / Optimisation strategies on assembly design are often relatively time expensive because of the large number of non-linear calculations (due to contact or friction problems) required to localize the optimum of an objective function. In order to achieve this kind of optimization problems with an acceptable computational time, this work propose to use a two-levels model optimization strategy based on two main tools: (1) the multiparametric strategy based on the LaTIn method that enables to reduce significantly the computational time for solving many similar mechanical assembly problems and (2) a cokriging metamodel built using responses and gradients computed by the mechanical solver on few sets of design parameters. The metamodel provides very inexpensive approximate responses of the objective function and it enables to achieve a global optimisation and to obtain the global optimum. The cokriging metamodel was reviewed in detail using analytical test functions and some mechanical benchmarks. The quality of the approximation and the building cost were compared with classical kriging approach. Moreover, a complete study of the multiparametric strategy was proposed using many mechanical benchmarks included many kinds and numbers of design parameters. The performance in term of computational time of the whole optimisation process was illustrated.
2

Exploring the Common Design Space of Dissimilar Assembly Parameterizations for Interdisciplinary Design

Larson, Brady M. 17 April 2008 (has links) (PDF)
The use of parametric CAD models in engineering, analysis, and optimization has greatly enhanced the effectiveness and efficiency of the product development process. Parametric models provide an attractive avenue for expansive design exploration. There still exists, however, a great challenge for products requiring design input from multiple disciplines. The collaboration of engineering disciplines can be hampered by many factors including: competing design objectives, communication of design changes, the use of different design and analysis software, and different geometry definitions. These obstacles become compounded when developing products at the assembly level. The use of solid parametric assembly models is not readily employed for products developed by groups from differing engineering disciplines. This is due to the huge cooperative effort required to create, analyze, and iterate on the geometry of the assembly model. The objective of this thesis is to present a method for separate disciplines to be able to analyze multiple parameterizations of the same CAD assembly to help develop a master parametric assembly, and to define the design space to be explored during analysis and optimization. This is done through a custom application developed using the Application Programming Interface of Siemens' NX CAD software. The custom application allows the user to monitor the affects of manipulating the driving parameters of an assembly by observing user specified geometry, features, or parametric expressions. The application also allows switching from one set of parametric design rules controlling the assembly to another in a matter of seconds. Manipulating and observing key geometry from different parameterizations allows engineering teams to discover the impact of each discipline's driving equations and geometry on another discipline. This will have a profound impact on multidisciplinary design teams in developing a robust parametric assembly, while still taking consideration of the requirements of each discipline. The collaborative efforts in the development of parametric assembly models used by multidisciplinary design teams are vastly improved through the method and application developed herein. This research will also show both the enhancements that could be made to existing CAD software, as well as the benefits of custom design tool development within the CAD environment.
3

Future Assembly Layout Design for assembly of large robots : A state-of-the-art literature review and a Fuzzy AHP analysis for ABB values

Karlqvist, Vanessa January 2020 (has links)
Global competition is growing for companies everywhere and the demand for new and improved products are rising for each day that passes. The globalization brings new opportunities as well as new challenges since companies need to stay up to date and implement new technologies to stay competitive. Not only do customers want up to date products, they also want high quality, low price and individualized products, customized for their needs. This puts high demand on manufacturing companies to adapt their businesses, increase product diversity and to being able to introduce new variations and new products quickly.  Since the drastic evolution of technology has increased the competitiveness of industrial companies, and the mass customization demands have increased, the necessity to investigate potential system alternatives towards improving production processes, with the help from the new technology, is required. One way of doing this is to revaluate one's assembly layouts since the layout design decision is highly connected to the product portfolio and the production volumes. The specific objective of this thesis is to broaden the case company’s, ABB, knowledge on ways their assembly of large robots can be improved with the focus on potential future assembly solutions. The overall aim of this thesis work is to identify state-of-the-art possible layout design alternatives, evaluate their performances and finding a method of choosing the final layout approach. This is answered by research questions connected to plant layout selection methodology, plant layout options and finally recommendations for the case company. The methodology chosen for deciding the recommended layout is the fuzzy Analytical Hierarchy Process which is a multi-criteria decision-making tool suitable for decision problems with a hierarchical structure, having main attributes and sub attributes connected to each main attribute. Twenty-four attributes were created and ten layouts based on company observations and a literature study. The layout with the highest score was a layout based on a modernized version of the common fixed position layout. The overall recommendation for the case company was to focus on having a layout in the future with focus on a high technology level as well as high flexibility, for also receiving high performance.
4

On The Mechanical Design of Power Dense Axial Flux Permanent Magnet Synchronous Motors for Aircraft Propulsion Applications

Duperly, Federico January 2024 (has links)
Traffic congestion in large urban and metropolitan areas is a substantial problem plaguing these areas. Not only are commuters losing valuable time, but greenhouse gas emissions are substantially worse because of congestion. Considerable research and development into next generation electrified aircraft is ongoing to introduce air mobility as a viable new means of transporting people and goods across long commutes. This development extends into commercial aviation as a whole as a means of reducing the industry’s carbon footprint with new aircraft designs that employ electrified propulsion systems. Many electrified aircraft projects are currently underway, ranging from small commuter aircraft all the way to large twin-aisle aircraft, and part of the development scope for alot of these projects is creating highly robust and power dense electric machines that replace the current state-of-the-art. The axial flux permanent magnet synchronous machine is an exciting candidate for aircraft propulsion due to its exceptional torque density and compact axial nature. In this thesis, the mechanical design for three generations of axial flux permanent magnet synchronous machines is discussed. These machines serve as development phase prototypes for machines that are ultimately intended for propulsion applications in commercial aviation, particularly for eVTOL aircraft. The motivation for electrification in the commercial aviation industry is discussed, followed by an overview of the development landscape for electrified propulsion systems in commercial aviation, focusing primarily on electric machines that are currently state-of-the-art or are set to be in the near future, as well as what is required for future electric machines in terms of power output and power density. The axial flux architecture is then presented, including a high-level comparison to the radial-flux architecture, an overview of the various axial flux machine designs and topologies, and a discussion of the inherent mechanical design challenges associated with the axial flux architecture. The yokeless and segmented armature axial flux permanent magnet synchronous machine design was selected for the machines developed as part of the research for this thesis, and the discussion of the mechanical design of these machines is broken up into the two core sub assemblies: stator assembly and rotating assembly. High-level design methodologies are introduced for both sub-assemblies, which is further broken down into different approaches pertaining to each generation. The first and second generation designs are presented at a high level, followed by deep-dives into the complete mechanical design for the third generation stator, the bearing selection, arrangement, and analysis for the third generation rotating assembly, and adhesive characterization trials used to guide adhesive selection for rotor magnetics retention in the second and third generation machines. The current status of the machines and any outcomes from testing that has been conducted thus far, particularly with respect to performance, is presented at the end. / Thesis / Master of Applied Science (MASc)
5

Stavebně technologický projekt přípravy a realizace polyfunkčního objektu v Brně / Construction Project for Implementation of Multifunctional Building in Brno

Čačaný, Lukáš January 2022 (has links)
The main subject of this diploma thesis is a construction technological project of preparation and realization multifunctional building in Brno on Trugeněvova street. It is a new construction of the main building. It provides a technical report on the construction technology project, transport relations for the transport of materials and machinery to the construction site, following technical report of construction site equipment, construction technology study, design of machinery and last but not least elaboration of technological regulation for the execution of monolithic structures. Furthermore, the chapters on health and safety protection at work on the construction site, as well as the LEED certification system and the financial and time plan of the selected stage are elaborated.
6

Assembly station development by flow analysis and systematic layout planning : Mapping of the current state of production, evaluation of alternatives and development of concepts for improved flow and flexibility

Abrahamsson, Oskar January 2021 (has links)
Modul system HH deliver modular storage systems and electrical solutions that can be combined according to the customer's wishes. This thesis combines argues for the importance for companies to keep improving their organization and production to remain competitive. By relating to a holistic view of the development of production environments, the project focuses on improvements for efficiency and social sustainability in the development of production. The project became relevant as the company has discovered difficulties in balancing production in the event of capacity changes and wants to develop rational flows and increase its flexibility. The project is limited to exploring three assembly stations and the operations and flows that belong to the assembly. The project spiral's iterative 3-step development process was chosen for strategic planning. This methodology allowed the work to continue forward despite the lack of data. The first step deals with planning and processes where technology and users were examined. In this planning phase, a Gantt schedule was used in the ClickUp program to plan the project and to-do lists and deadlines could be set. A literature study was conducted to strengthen arguments and raise new ideas. The theoretical overview focuses on areas around production development with a focus on the development of layouts/assembly stations, psychosocial work environment and organizational management. In the second phase of the project, requirements and wishes were mapped. This was done together with the company, the results from this step were then used to evaluate concepts before detailed development. The project also has several parts of the framework that Muther & Wheeler developed called Systematic layout planning. It provided the tools to understand important connections through relationships and proximity analysis. These methods were also used to evaluate the results. Interviews, observations, and 3D modelling were also performed in this phase to gather information and to understand different production structures. Semi-structured interviews were performed with product managers, production designers, production planners. From these methods, I was together with some employees able to conclude that customer order-driven product development is the focus. That production places demand on rapid implementations in production and that modularity means great flexibility needs and fast lead times. We also found opportunities to minimize repetitive and time-consuming steps through development based on the operator's point of view. Concepts were developed through a development process based on proximity analysis, time studies and results from more subjective interviews. The concepts were then evaluated through an evaluation matrix based on formulated future requirements and wishes. The winning concept was developed in more detail and developed iteratively together with staff from the company. The final concept combines a new, more compact layout that considers proximity requirements between stations as well as flows of materials and operators. The final layout also introduces new types of material buffers and action proposals for improved collaboration and communication for increased flexibility.
7

Skladová a expediční hala včetně rekonstrukce-stavebně technologický projekt / Storage and dispatch hall including the reconstruction - building-technology project

Toman, Jan January 2014 (has links)
Subject of this thesis is construction technology project storage and dispatch hall in Třebíč. This thesis contains technical report, construction site equipment project, time and financial plan, bill of quantities, technology study of the major technology stages, mechanical assembly design, technological specification, quality inspections.
8

Výrobní hala nástrojárny firmy TOKOZ - stavebně technologický projekt / Production hall of toolmaking company TOKOZ - Construction and technology project

Chytal, Roman January 2015 (has links)
The thesis is focused on building technology solutions construction production hall toolmaking of company TOKOZ,a.s. in Žďár nad Sázavou. This thesis contains technical report, construction site equipment project, time and financial plan, bill of quantities, technology study of the major technology stages, mechanical assembly design, technological specification, quality inspections and risks in the implementation of ground works.

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