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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

Designing Active Smart Features to Provide Nesting Forces in Exactly Constrained Assemblies

Pearce, Eric 07 May 2003 (has links) (PDF)
Ever since the design and manufacture of products moved from the craftsman era where individual craftsman designed and manufactured the entire product, to the mass production era, where skilled laborers were crafting interchangeable parts or in some cases single features on interchangeable parts, variation in assemblies has been a major concern to designers, manufacturers, and in a more subtle way, customers. Variation, in the end, affects quality, performance and the cost of products. One particular type of design that is particularly robust to variation is an exactly constrained design. Several researchers have recently explored the topic of exact constraint design. An exactly constrained design is one in which each degree of freedom is constrained by a single constraint until the desired degrees of freedom for the design is attained. One attractive advantage of exactly constrained designs is that they are robust to variation. However, exactly constrained designs often require nesting forces to maintain the configuration of the design. This research develops a method for designing features that will supply robust nesting forces such that the advantages of the exactly constrained design are preserved. The method developed in this work takes advantage of a proven method for tolerance analysis and enhances this method to include the analysis of these features that supply nesting forces. Along with the enhancement, principles are developed that aid this analysis. All the examples provided in this work are verified using comparisons to Monte Carlo simulations. The comparisons show good results, typically less than 2% difference from the Monte Carlo simulations, verifying that this method accurately predicts variation and allows for the robust design of features that supply the nesting forces in exactly constrained assemblies.
2

Intégration de modèles de jonctions dissipatives dans la conception vibratoire de structures amorties / Integration of dissipative joints models in the vibratory design of damped structures

Hammami, Chaima 14 October 2014 (has links)
La dissipation dans les systèmes mécaniques joue un rôle important dans la limitation des niveaux de vibrations qui peuvent causer des difficultés allant de l'inconfort jusqu'à la ruine des structures. L'amortissement intrinsèque des matériaux utilisés pour la fabrication de structures aéronautiques étant très faible, les jonctions représentent une des sources principales de dissipation. Dans le cadre du projet FUI MAIAS (Maitrise des Amortissements Induits dans les ASsemblages), les travaux présentés ici portent sur la maximisation de l'amortissement induit. Une grande partie des travaux de littérature s'intéressent à l'étude de jonctions élémentaires. On cherche donc ici à étudier la conception de jonctions dissipatives intégrées dans une structure globale. Pour limiter les applications, on se restreint plus particulièrement aux jonctions boulonnées rencontrées en construction aéronautique et à l'utilisation de matériaux viscoélastiques pour générer la dissipation.Une notion de couplage pour la mesure de la capacité des liaisons à dissiper est introduite pour s'assurer de leurs contributions au comportement vibratoire. En utilisant le couplage en tant que mesure de sensibilité des jonctions aux propriétés des matériaux viscoélastiques, en plus de l'étude de la tenue fonctionnelle d'une liaison boulonnée, une approche de conception de jonction boulonnée dissipative est alors développée. Une étude expérimentale est ensuite effectuée pour la valider. Lors de la compagne d‘essais, des défauts de forme ont été détectés dans la structure. L'influence de ces défauts, susceptibles d'exister dans les structures réelles, sur l'amortissement est alors décrite. L'intégration pour un grand nombre de modèles physiques, détaillés au voisinage des jonctions, dans un modèle d'ensemble est généralement une problématique. Une représentation simplifiée s'avère être alors nécessaire. Une réduction de modèle peut être alors appliquée sur la partie linéaire du système. Cependant, pour les non-linéarités localisées au niveau des jonctions, une construction de méta-modèle caractérisant les efforts transmis dans les liaisons est alors proposée. Différentes stratégies de construction de méta-modèle, reproduisant les déformations et les efforts principaux de liaisons, sont proposées et étudiées en supposant des liaisons à comportement viscoélastique. Un modèle cylindrique à dix jonctions boulonnées, plus représentatif de l'architecture réelle des structures aéronautiques est étudié pour illustrer le cas des liaisons répétées dont le chargement réel de chacune est beaucoup plus complexe que les structures simples couramment étudiées. / Dissipation in mechanical systems plays an important role in limiting vibrationlevels. The present work deals with maximizing damping induced by junctions and treatsjunctions integrated into an overall structure. After introducing the physical models used inrepresenting viscoelastic behavior, a first example introduces the concept of coupling. Coupling,estimated by preliminary calculations of elastic natural frequencies sensitivity, ensures thatjunctions sufficiently contribute to the global behavior to induce damping. To study this couplingas well as obtain accurate damping predictions by complex modes calculation, model reductionmethods, adapted to parameterized problems, are needed and different strategies are detailedand validated. A structure representing aeronautic construction is then used to illustrate theproposed damping design process. The study highlights the functional importance of thecohesive zone under the bolt and the possibility of using the residual flexibility of the joint tointroduce a viscoelastic layer enabling high damping. Experimental modal tests confirm thevalidity of the design and the predicted trends, but also show the influence of manufacturingdefects which limit the induced damping. The manuscript finally addresses the need forrepresentative models of detailed joints in overall models. Although model reduction is possibleand desirable, the construction of meta-models representing the main forces transmitted by thejoints is useful in modeling and necessary for the operation of elementary tests. Generalstrategies for defining principal deformations and loads are introduced and their validity isillustrated.
3

Developing A Dialogue Based Knowledge Acquisition Method For Automatically Acquiring Expert Knowledge To Diagnose Mechanical Assemblies

Madhusudanan, N 12 1900 (has links) (PDF)
Mechanical assembly is an important step during product realization, which is an integrative process that brings together the parts of the assembly, the people performing the assembly and the various technologies that are involved. Assembly planning involves deciding on the assembly sequence, the tooling and the processes to be used. Assembly planning should enable the actual assembly process to be as effective as possible.Assembly plans may have to be revised due to issues arising during assembly. Many of these revisions can be avoided at the planning stage if assembly planners have prior knowledge of these issues and how to resolve them. General guidelines to make assembly easier (e.g. Design for Assembly) are usually suited for mass-manufactured assemblies and are applied where similar issues are faced regularly. However, for very specific issues that are unique to some domains only, such as aircraft assembly, only expert knowledge in that domain can identify and resolve the issues. Assembly experts are the sources of knowledge for identifying and resolving these issues. If assembly planners could receive assembly experts’ advice about the potential issues and resolutions that are likely to occur in a given assembly situation, they could use this advice to revise the assembly plan in order to avoid these issues. This link between assembly experts and planners can be provided using knowledge based systems. Knowledge-based systems contain a knowledge base to store experts’ knowledge, and an inference engine that derives certain conclusions using this knowledge. However, knowledge acquisition for such systems is a difficult process with substantial resistance to being automated. Methods reported in literature propose various ways of addressing the problem of automating knowledge acquisition. However, there are many limitations to these methods, which have been the motivations for the research work reported in this thesis. This thesis proposes a dialog-like method of questioning an expert to automatically acquire knowledge from assembly experts. The questions are asked in the context of an assembly situation shown to them. During the interviews, the knowledge required for diagnosing potential issues and resolutions are identified. The experts were shown a situation, and asked to identify issues and suggest solutions. The above knowledge is translated into the rules for a knowledge based system. This knowledge based system can then be used to advise assembly planners about potential issues and solutions in an assembly situation. After a manual verification, the questioning procedure has been implemented on computer as a software named EXpert Knowledge Acquisition and Validation (ExKAV). A preliminary evaluation of ExKAV has been carried out, in which assembly experts interacted with the tool using the researcher as an intermediary. The results of these sessions have been discussed in the thesis and assessed against the original research objectives. The current limitations of the procedure and its implementation have been highlighted, and potential directions for improving the knowledge acquisition process are discussed.
4

Stavebně technologický projekt rekonstrukce areálu bývalého mlýna v Židlochovicích / Constructive technological project of reconstruction

Tacina, Marek January 2015 (has links)
The subject of my thesis is to implement the gross carrying construction of the new bakery Karlovy pekarny in Židlochovice. In this paper dealt with the technical report, the situation of buildings, building equipment, budget, schedule, technological procedure of construction (bored piles and assembled skeleton), mechanical design and assembly KZP.
5

Vybrané části stavebně technologického projektu muzea motorsportu / Selected parts of constructional and technological project of motorsport museum

Kubrtová, Zuzana January 2016 (has links)
In this thesis I will deal with structural and technological preparation ELIZABETH - MUZEUM MOTORSPORTU. As a specific phase of construction, which I will focus, I chose a solution glass facade, designed by Schüco. This is the glass panels mounted in an aluminum frame. My work includes technical report, technological prescription for the installation of facades, design mechanical assemblies, time and financial plan, control plan and test plan.
6

Stavebně technologický projekt haly Argos Elektro v Ostravě / Construction technological project of Argos Elektro hall in Ostrava

Vrána, Tomáš January 2017 (has links)
This thesis deals with the construction and technological project for construction of a storage and office buildings Argos Elektro in Ostrava. The thesis contains a technical report object, construction schedule, report building equipment, design mechanical assembly, technological specification for the shell construction, technological prescription for pilots, inspection and test plans, risks and safety measures, structural details and itemized construction budget.
7

Bytový dům Ivančice - stavebně technologický projekt / Apartment building in Ivančice - construction technology project

Fejfar, Michal January 2018 (has links)
The subject of the master´s thesis technological project of the Ivančice residential building in Ivančice. The building has one underground and four aboveground floors. The master´s thesis contains a technical report for the building technology project, broader transport routes, a timetable, a financial plan, time schedule, design of construction site installations, design of mechanical assemblies, technological prescription for construction of celling white tank, inspection and test plan, crane and design.

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