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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.
151

Návrh nové evoluce trubkového rámu vozidla Formule Student / Formula Student Tubular Frame New Evolution Design

Slimařík, Dušan January 2012 (has links)
Design of new evolution steel welded tubular frame specified for Formula Student series is the main goal of this thesis. In the first instance, type of frame designs is described. Next part of thesis is devote to rules, which must be respected in designing of new evolution of tubular frame. In main part, construction design and calculations of torsional stiffness using MKP analysis are mentioned. Interesting point of this work is located at penultimate part, which deals with preparation of tubular frame production. This is integral part of the construction process at all. Thesis ends with project summary.
152

Hnací ústrojí nákladního vozidla 8x8 / Drivetrain of a 8x8 truck

Hebnar, Tomáš January 2013 (has links)
This thesis is focused on building a replacement torsion system of drivetrain of 8x8 and 8x4 trucks and subsequent computational analyses of built systems. There were made two analyses. The first one is a computational analysis of the shapes of vibration and The second one is a sensitivity analysis. The sensitivity analysis is studying effect on the size of the natural frequencies under the effect of gear ratio.
153

Dvouválcový čtyřdobý plochý zážehový motor / Two-cylinder four stroke spark ignition flat engine

Dragoun, Jan January 2012 (has links)
This thesis deals with the possibilities for realization of the crankshaft-cylinder four-stroke gasoline engine is flat, usable in the urban vehicle. In the work described stresses exerted on the crank mechanism can balance the crankshaft, torsional stress and strength calculation method of control. In the final part of this work is outlined proposal for implementation of the crankshaft.
154

Rám formulového vozu s návrhem upevňovacích prvků karosérie / Formula Frame Design with Bodywork Fastening Solution

Trněný, Pavel January 2013 (has links)
This masters thesis concernes with design of formula student frame. Part of masters thesis is to a overview of possible solutions. The main criterion in frame design is final torsional stiffness. Another part of frame design is too solution of suspension attachement to frame. In next part of masters thesis is solved bodywork design and it´s fastening to frame. Final part has few informations about frame manufacturing.
155

Torzní tuhost rámu Formule Student / Torsional stiffness of Formula Student frame

Jurnečka, Ladislav January 2014 (has links)
Diploma thesis deals with detection of torsional stiffness with using photogrammetric equipment TRITOP device and subsequent comparison with created computational model in FEM software. Measurement and calculations were accomplished according to tutorials, which are the most effective and giving the most accurate results. Next the optional method of measurement of torsional stiffness in practice is formed for future formula series called Dragon. The reasons of different results and suggestion of optimalization are sum up in the end of the thesis.
156

Dvouválcový řadový vznětový motor s excentrickým klikovým mechanismem pro užitková vozidla / Two-cylinder inline diesel engine with an eccentric crank for commercial vehicles

Černohous, Tomáš January 2015 (has links)
The goal of this master’s thesis is to examine the influence of eccentricity on the behaviour of forces between the piston and cylinder liner and on balancing of the crank mechanism for given parameters of the diesel engine. Another aim of this paper is to propose an appropriate balancing of the crank mechanism followed by stress analysis considering torsional vibration for a chosen value of eccentricity.
157

Dvouválcový zážehový motor s excentrickým klikovým mechanismem pro osobní vozidla / Two-cylinder petrol engine with eccentric crank mechanism for passenger vehicles

Freisleben, Pavel January 2015 (has links)
This thesis deals with forces of the crank mechanism. The aim of this work is to find the right value of the eccentricity of the crank mechanism, which will have a positive effect on the size and course of forces that cause friction losses in the crank mechanism. Next solves this balancing eccentric unit. The last part deals with the design and strength check of the crankshaft considering torsional vibration.
158

Lateral Torsional Buckling of Timber Built-up Beams

Robatmili, Robabeh 11 May 2022 (has links)
Built-up timber beams consist of individual lumber laminations connected together using mechanical fasteners such as nails, bolts and screws. Lateral torsional buckling (LTB) is an important failure mode that needs to be considered in deep beams with long spans and insufficient lateral supports. Due to the mechanical connectors, built-up beams are expected to have a lower moment capacity compared with solid beams with similar dimensions. The behaviour of built-up beams is greatly affected by the stiffness of the fasteners joining the individual laminations and determining the level of partial composite action attained in the beam. The current research aims to investigate the buckling behaviour of timber built-up beams. This is done by initially investigating the important parameters that play a role in the behaviour through an extensive sensitivity analysis. The focus of the analysis is on the contribution of the connections, since the buckling behaviour of individual solid timber beam element has been relatively well-established. Input parameters for the connection properties are obtained from joint level experimental tests. Finally, recommendations for specific fastener patterns and accompanying reduction factors on the buckling capacity relative to equivalent solid sections are developed and proposed.
159

Lateral-Torsional Buckling Instability Caused by Individuals Walking on Wood Composite I-Joists

Villasenor Aguilar, Jose Maria 14 January 2013 (has links)
Recent research has shown that a significant number of the falls from elevation occur when laborers are working on unfinished structures. Workers walking on wood I-joists on roofs and floors are prone to fall hazards. Wood I-joists have been replacing dimension lumber for many floor systems and a substantial number of roof systems in light-frame construction. Wood I-joists are designed to resist axial stresses on the flanges and shear stresses on the web while minimizing material used. However, wood I-joists have poor resistance to applied lateral and torsional loads and are susceptible to lateral-torsional buckling instability. Workers walking on unbraced or partially braced wood I-joists can induce axial and lateral forces as well as twist. Experimental testing demonstrated that workers cause lateral-torsional buckling instability in wood I-joists. However, no research was found related to the lateral-torsional buckling instability induced by individuals walking on the wood I-joists. Furthermore, no research was found considering the effects of the supported end conditions and partial bracing in the lateral-torsional buckling instability of wood I-joists. The goal of this research was to derive mathematical models to predict the dynamic lateral-torsional buckling instability of wood composite I-joists loaded by individuals walking considering different supported end conditions and bracing system configurations. The dynamic lateral-torsional buckling instability was analyzed by linearly combining the static lateral-torsional buckling instability with the lateral bending motion of the wood I-joists. Mathematical models were derived to calculate the static critical loads for the simply supported end condition and four wood I-joist hanger supported end conditions. Additionally, mathematical models were derived to calculate the dynamic maximum lateral displacements and positions of the individual walking on the wood I-joists for the same five different supported end conditions. Three different lean-on bracing systems were investigated, non-bracing, one-bracing, and two-bracing systems. Mathematical models were derived to calculate the amount of constraint due to the lean-on bracing system. The derived mathematical models were validated by comparison to data from testing for all supported end conditions and bracing systems The predicted critical loads using the static buckling theoretical models for the non-bracing system and the static buckling theoretical models combined with the bracing theoretical models for the simply and hanger supported end conditions agreed well with the critical loads obtained from testing for the two wood I-joist sizes investigated. The predicted maximum lateral displacements and individual positions using the bending motion theoretical models for the simply and hanger supported end conditions agreed well with the corresponding maximum lateral displacements and individual positions obtained from testing for both wood I-joist sizes. Results showed that; a) the supported end condition influenced the critical loads, maximum lateral displacements and individual positions, b) the bracing system increased the critical loads and reduced the maximum lateral displacements, c) the critical load increased as the load position displaced away from the wood I-joist mid-span, d) the critical load reduced as the initial lateral displacement of the wood I-joist increased and e) the wood I-joist mid-span was the critical point in the dynamic lateral-torsional buckling instability. / Ph. D.
160

Implementation of smartphone-based experimental exercises for physics courses at universities

Kaps, Andreas, Splith, Daniel Thomas, Stallmach, Frank 02 May 2023 (has links)
A concept for undergraduate mechanics courses at universities is introduced where traditional pencil-paper based exercises are partially replaced by experimental exercises, in which smartphones are used as measurement devices. A detailed guidance for practical realization and implementation of these tasks formats into the course is presented. Three smartphone-based experimental exercises ‘The tilting smartphone’, ‘The oscillation balance’ and ‘Using the Smartphone in a Torsion Pendulum’ are presented. First empirical results with respect to the learning achievement indicate a mid size effect on the understanding of the physical concepts. Compared to the traditional pencil-paper based exercises, the students performance in the experimental exercises is slightly lower, although the motivation to solve these tasks is higher.

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