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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

Výroba příruby přesným stříháním / The manufacturing of a flange by fineblanking technology

Povalač, Tomáš January 2013 (has links)
Aim of the project is to design new flange manufacturing technology. The flange is manufactured from stainless sheet 17 040 with 5 mm thickness and annual production batch of 800 000 pieces. Fineblanking process has been proposed as a new production technology. Technological and construction dimensions have been designed for the proposed technology. The fineblanking process is done by automated machine which consist of unwinding and straightening device, mechanical punch press and winding device. The manufactured part is punch pressed by tool which is located in the punch press in one lift. An economic evaluation compares current manufacturing technology with the proposed technology which is more economically convenient.
32

Napěťově deformační analýza přírubového spoje / Stress and deformation analyses of the flange connection

Lehnert, Ondřej January 2016 (has links)
This master thesis deals with analytical calculation of the various flange connections using theory of thin-walled bodies and axisymmetric assumptions. The calculation is demonstrated by one specific geometry configuration. Numerical finite element method was performed to verify analytical calculation model and also this method enabled more in-depth analysis of the prying effect which has negative influence on the bolt connection tensile load. Output from this analysis is prying point location function in plate thickness dependence and application this function into analytical calculation.
33

Wheel Wear Simulation of the Light Rail Vehicle A32

Robla Sánchez, Ignacio January 2010 (has links)
During the last decade, a novel methodology for wheel wear simulation has been developed in Sweden. The practical objective of this simulation procedure is to provide an integratedengineering tool to support rail vehicle design with respect to wheel wear performance and detailed understanding of wheel-rail interaction. The tool is integrated in a vehicle dynamicssimulation environment.The wear calculation is based on a set of dynamic simulations, representing the vehicle, the network, and the operating conditions. The wheel profile evolution is simulated in an iterativeprocess by adding the contribution from each simulation case and updating the profile geometry.The method is being validated against measurements by selected pilot applications. To strengthen the confidence in simulation results the scope of application should be as wide aspossible in terms of vehicle classes. The purpose of this thesis work has been to try to extend the scope of validation of this method into the light rail area, simulating the light rail vehicleA32 operating in Stockholm commuter service on the line Tvärbanan.An exhaustive study of the wear theory and previous work on wear prediction has been necessary to understand the wear prediction method proposed by KTH. The dynamicbehaviour of rail vehicles has also been deeply studied in order to understand the factors affecting wear in the wheel-rail contact.The vehicle model has been validated against previous studies of this vehicle. Furthermore new elements have been included in the model in order to better simulate the real conditionsof the vehicle.Numerous tests have been carried out in order to calibrate the wear tool and find the settings which better match the real conditions of the vehicle.Wheel and rail wear as well as profile evolution measurements were available before this work and they are compared with those results obtained from the simulations carried out.The simulated wear at the tread and flange parts of the wheel match quite well the measurements. However, the results are not so good for the middle part, since themeasurements show quite evenly distributed wear along the profile while the results from simulations show higher difference between extremes and middle part. More tests would benecessary to obtain an optimal solution.
34

The Effects of Shear Deformation in Rectangular and Wide Flange Sections

Iyer, Hariharan 16 March 2005 (has links)
Shear deformations are, generally, not considered in structural analysis of beams and frames. But shear deformations in members with low clear span-to-member depth ratio will be higher than normally expected, thus adversely affecting the stiffness of these members. Inclusion of shear deformation in analysis requires the values of shear modulus (modulus of rigidity, G) and the shear area of the member. The shear area of the member is a cross-sectional property and is defined as the area of the section which is effective in resisting shear deformation. This value is always less than the gross area of the section and is also referred to as the form factor. The form factor is the ratio of the gross area of the section to its shear area. There are a number of expressions available in the literature for the form factors of rectangular and wide flange sections. However, preliminary analysis revealed a high variation in the values given by them. The variation was attributed to the different assumptions made, regarding the stress distribution and section behavior. This necessitated the use of three-dimensional finite element analysis of rectangular and wide flange sections to resolve the issue. The purpose of finite element analysis was to determine which, if any, of the expressions in the literature provided correct answers. A new method of finite element analysis based on the principle of virtual work is used for analyzing rectangular and wide flange sections. The validity of the new method was established by analyzing rectangular sections for which closed form solutions for form factor were available. The form factors of various wide flange sections in the AISC database were calculated from finite element analysis and an empirical relationship was formulated for easy calculation of the form factor. It was also found that an empirical formula provided good results for form factors of wide flange sections. Beam-column joint sub-assemblies were modeled and analyzed to understand the contribution of various components to the total drift. This was not very successful since the values obtained from the finite element analysis did not match the values calculated using virtual work. This discrepancy points to inaccuracies in modeling and, possibly, analysis of beam-column joints. This issue needs to be resolved before proceeding further with the analysis. / Master of Science
35

Detailed Fem Analysis Of Two Different Splice Steel Connections

Yilmaz, Oguz 01 September 2008 (has links) (PDF)
Beam splices are typically located at moment contraflexure points (where M=0). Most design specifications require these splices to develop a strength either to meet design forces or a minimum value set by specifications. The design forces are typically determined through elastic analysis, which does not include flexibility of splice connections. In this research, two types of splice connections, an extended end plate splice connection and a flange and web plate bolted splice connection, were tested and analyzed to investigate the effect of the partial strength splice connections on structural response. The splices were designed to resist 40% and 34% of connecting section capacities using current steel design codes, respectively. It has been observed from the experiments and FEM analysis results that splice connections designed under capacities of connecting steel members can result in changes in design moment diagrams obtained from analyses without splice connection simulation and can also significantly decrease the rigidity of the structure endangering serviceability. The differences in design moment diagrams can go up to 50 % of elastic analysis without connection flexibility. The vertical displacements can increase to 155% of values obtained from elastic analysis with no splice connection simulation. Therefore, connection flexibility becomes very important to define in analysis.
36

Dokumentation von Versuchen zur mitwirkenden Plattenbreite an Plattenbalken / Documentation of Experiments on Effective Flange Width of T-Beams

Wiese, Hans 11 July 2007 (has links) (PDF)
Als Ergänzung für die Lehrbriefe des Instituts für Massivbau der TU Dresden zu den Grundlagen des Stahlbetons (Teil 1 und 3 sowie Übungen Teil 1 bis 3) werden hier Bilder von Versuchsreihen vorgestellt, die am Lehrstuhl für Stahlbeton, Spannbeton und Massivbrücken der TH/TU Dresden, aus dem das heutige Institut für Massivbau hervorging, innerhalb verschiedener Forschungsarbeiten von 1956 bis 1965 entstanden. Neben dem Einblick in die damaligen Arbeitsweisen und Möglichkeiten sind vor allem die zahlreichen Bruchbilder geeignet, sich in das Tragverhalten des Stahlbetons hineinzudenken. Diese Überlegungen gaben den Ausschlag dafür, das vorhandene Bildmaterial noch einmal zu ordnen und mit kurzen Erläuterungen zu versehen, um es so nochmals für Lehre und Forschung nutzbar zu machen.
37

Stress-Deformation Theories for the Analysis of Steel Beams Reinforced with GFRP Plates

Phe, Pham Van 29 November 2013 (has links)
A theory is developed for the analysis of composite systems consisting of steel wide flange sections reinforced with GFRP plates connected to one of the flanges through a layer of adhesive. The theory is based on an extension of the Gjelsvik theory and thus incorporates local and global warping effects but omits shear deformation effects. The theory captures the longitudinal transverse response through a system of three coupled differential equations of equilibrium and the lateral-torsional response through another system of three coupled differential equations. Closed form solutions are developed and a super-convergent finite element is formulated based under the new theory. A comparison to 3D FEA results based on established solid elements in Abaqus demonstrates the validity of the theory when predicting the longitudinal-transverse response, but showcases its shortcomings in predicting the torsional response of the composite system. The comparison sheds valuable insight on means of improving the theory. A more advanced theory is subsequently developed based on enriched kinematics which incorporates shear deformation effects. The shear deformable theory captures the longitudinal-transverse response through a system of four coupled differential equations of equilibrium and the lateral-torsional response through another system of six coupled differential equations. A finite difference approximation is developed for the new theory and a new finite element formulation is subsequently to solve the new system of equations. A comparison to 3D FEA illustrates the validity of the shear deformable theory in predicting the longitudinal-transverse response as well as the lateral-torsional response. Both theories are shown to be computationally efficient and reduce the modelling and running time from several hours per run to a few minutes or seconds while capturing the essential features of the response of the composite system.
38

Influence des défauts de forme sur les performances d'assemblages : application aux prothèses totales de hanche / Influence of form errors on assemblies performance : application on total hip implants

Grandjean, Julien 29 October 2013 (has links)
La performance des mécanismes est intimement liée à la précision des surfaces qui composent les liaisons. La démarche habituelle de l’analyse de ces surfaces est basée sur des hypothèses fortes concernant leurs comportements. Ainsi, les défauts de forme et de rugosité sont négligés et les surfaces sont supposées infiniment rigides. L’objectif principal de ces travaux est de développer une méthode permettant d’étudier l’influence des défauts de forme sur les performances des assemblages. Elle repose sur une méthodologie et des outils pour l’identification des défauts qui vont optimiser ou pénaliser les exigences fonctionnelles de l’assemblage. Dans ce manuscrit, deux cas d’étude sont proposés.Dans un premier temps, un montage de type bride (centrage court, appui plan) est étudié afin de valider l’ensemble de la démarche développée. Les outils utilisés reposent essentiellement sur la décomposition et composition modale des défauts, le concept de surface écarts, la recherche de zone d’appui stable ainsi que la quantification des déformations de surfaces de contact basées sur des modèles analytiques ou numériques. L’influence des défauts de forme sur la précision de mise en position est quantifiée par un domaine écart de liaison. Une confrontation entre la démarche théorique et un dispositif expérimental permet de valider l’approche. Par la suite, une liaison sphérique est considérée constituant une prothèse totale de hanche en matériau céramique. Pour ce cas d’étude, l’objectif est d’identifier, au regard des typologies de défauts, leurs conséquences sur l’apparition d’un phénomène sonore assimilable à du grincement appelé le squeaking. La démarche reprend les mêmes étapes que celles utilisées avec l’étude de la bride. Différents dispositifs expérimentaux sont mis en place confirmant la pertinence de cette approche. Des mesures spécifiques apportent des éléments d’analyse et de compréhension sur le comportement dégradé de la liaison. Ce travail de thèse s’inscrit dans une collaboration entre 3 laboratoires : SYMME d’Annecy, I2M-IMC de Bordeaux-Talence, et la société Tural localisée à Marignier (74), laboratoire de recherche industrielle qui travaille sur des implants médicaux. / The performance of a mechanism is closely correlated with the accuracy of the surfaces that make up the mechanical joint. The most common approach used to study these surfaces is based on strong assumptions about their behavior. Form errors and roughness are neglected and the surfaces are assumed infinitely rigid. The main objective of this work is to develop an original approach to study the impact of form errors on the assemblies. It is mainly based on a methodology and associated tools to predict which defects will optimize or penalize the functional requirements of the assembly. In this manuscript, two case studies are proposed. In a first step, a plate flange (ball and cylinder joints added to a planar joint) is designed to validate the overall approach. Modal decomposition of defects, sum-surface concept, the determination of a stable contact area and quantification of contact deformation of surfaces correspond to the main theoretical tools used in this framework. The influence of form errors on the positioning accuracy is quantified by a clearance domain. Comparisons between theoretical approach and experimental setup are used to validate the models. Subsequently, a spherical joint is considered corresponding to a total hip implant with ceramic material. The objective of this study is to identify which type of form errors can impact the appearance of the squeaking phenomena. The same procedure is followed as for the first example. In parallel, several experimental devices are designed to validate the relevance of this approach. Specific measurements provide some key elements to understand the behavior of the implant subject to squeaking. This work is part of a collaboration between three laboratories : SYMME Annecy, I2M-IMC Bordeaux, and Tural company located in Marignier (74), an industrial research laboratory working on medical implants.
39

Prediction of DP steel fracture by FEM simulationsusing an advanced Gurson model / Prédiction par éléments finis de la rupture des aciers Dual-Phase en utilisant un modèle de Gurson avancé

Fansi, Joseph 02 July 2013 (has links)
L'actuel investigation numérique du Gurson-Tvergaard-Needleman (GTN) modèle avancé est une extension du travail de Ben Bettaieb et al. (2011). Le modèle a été implémenté à l'aide d'une sous routine (VUMAT) contenu dans le code commerciale d'éléments finis Abaqus/explicit. Le modèle d'endommagement améliore l'original en intégrant les trois mécanismes d'endommagement, la nucléation, la croissance, et la coalescence des cavités. Le modèle d'endommagement intègre les lois de nucléation et de croissance basés sur les phénomènes purement physiques. Ces nouvelles contributions incluant l'influence de l'écrouissage cinématique, ont été validées par les résultats de mesures expérimentales de tomographie à rayon X à haute résolution. Aussi, l'implémentation numérique de l'écrouissage cinématique dans le modèle modifié a contraint de proposer et de réarranger la définition de la triaxialité que l'on trouve habituellement dans la littérature. A coté de cela, un second critère d'initiation à la rupture basé sur l'ultime distance inter-cavités a été inclue afin de localiser et de quantifier avec plus de précision la distribution des déformations peu avant que le matériau ne casse complètement. L'actuel modèle d'endommagement a été appliqué dans des conditions industrielles pour prédire l'évolution de l'endommagement, l'état de contraintes, et l'initiation à la rupture pour différentes géométries de tôles et sur des essais d'emboutissage de tôles minces. / This numerical investigation of an advanced Gurson–Tvergaard–Needleman (GTN) model is an extension of the original work of Ben Bettaieb et al. (2011). The model has been implemented as a user-defined material model subroutine (VUMAT) in the Abaqus/explicit FE code. The current damage model extends the previous version by integrating the three damage mechanisms: nucleation, growth and coalescence of voids. Physically based void nucleation and growth laws are considered, including an effect of the kinematic hardening. These new contributions are based and validated on experimental results provided by high-resolution X-ray absorption tomography measurements. Also, the numerical implementation of the kinematic hardening in this damage extension has obliged to readapt the classical triaxiality definition. Besides, a secondary fracture initiation criterion based on the ultimate average inter-cavities distance has been integrated to localize and quantify with good accuracy the strain distribution just before the material fails apart. The current damage model is applied in industrial conditions to predict the damage evolution, the stress state and the fracture initiation in various tensile thin flat sheet geometries and the cross-die drawing tests.
40

Stress-Deformation Theories for the Analysis of Steel Beams Reinforced with GFRP Plates

Phe, Pham Van January 2013 (has links)
A theory is developed for the analysis of composite systems consisting of steel wide flange sections reinforced with GFRP plates connected to one of the flanges through a layer of adhesive. The theory is based on an extension of the Gjelsvik theory and thus incorporates local and global warping effects but omits shear deformation effects. The theory captures the longitudinal transverse response through a system of three coupled differential equations of equilibrium and the lateral-torsional response through another system of three coupled differential equations. Closed form solutions are developed and a super-convergent finite element is formulated based under the new theory. A comparison to 3D FEA results based on established solid elements in Abaqus demonstrates the validity of the theory when predicting the longitudinal-transverse response, but showcases its shortcomings in predicting the torsional response of the composite system. The comparison sheds valuable insight on means of improving the theory. A more advanced theory is subsequently developed based on enriched kinematics which incorporates shear deformation effects. The shear deformable theory captures the longitudinal-transverse response through a system of four coupled differential equations of equilibrium and the lateral-torsional response through another system of six coupled differential equations. A finite difference approximation is developed for the new theory and a new finite element formulation is subsequently to solve the new system of equations. A comparison to 3D FEA illustrates the validity of the shear deformable theory in predicting the longitudinal-transverse response as well as the lateral-torsional response. Both theories are shown to be computationally efficient and reduce the modelling and running time from several hours per run to a few minutes or seconds while capturing the essential features of the response of the composite system.

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