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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.
141

Návrh speciálních asfaltových směsí SAL určených pro opravu cementobetonových krytů / Design of special asphalt mixtures SAL for the repair of cement concrete pavements

Kalfeřt, Martin January 2014 (has links)
In this thesis layer with increased resistance to crack propagation (SAL) are designed. The theoretical part describes the SAL layer, further the input materials, their production and design of various mixtures. The following is a description of the tests, which include tests of permanent deformation, crack propagation, low-temperature characteristics, test, flexural strength and relaxation. After the test results and conclusion are stated.
142

Stanovení zbytkové napjatosti metodou vrtání otvoru s využitím MKP / Assesment of residual stress with drilling hole method using FEM

Civín, Adam January 2008 (has links)
Residual state of stress in structural materials affect positively or negatively behaviour of component parts. The goal of this scope is not to deal with possible process of creating residual stresses neither about elimination of residual stress, but is focused how to determine magnitude of residual stress by hole-drilling method. We need to know magnitude and direction (angular orientation) of principal stresses to determine how residual state of stress affects behaviour of specimen. The most widely used modern technique for measuring residual stresses is hole-drilling strain-gage method. Hole-drilling method is in scope of this paper and is restricted only for measuring uniform residual stresses of steel specimens with finite dimensions. Structural, linear, elastic and isotropic material model is used with material properties =0,3 and E=2,1[10]^5 MPa. For correct application of this method we need to determine calibration coefficients “a“ and “b“ first. These coefficients are used to determine magnitude and direction of residual stresses in specific depth and diameter of drilled hole for materials with finite dimensions. Geometry and shape of model is simply represented by block with planar faces. Note that numerical determination of calibration coefficients is useful only for one type of strain gauge rosette RY 61 S. Main goals of this thesis are motivation and request to clearly report effectiveness, accuracy and applicability of calibration coefficients in relation to thickness of specimen, dimensions of drilled hole, condition of “through” or “blind” hole and number of drilled increments. High quality and accuracy of created numerical model is necessary too. Numerical simulation of residual stresses by MKP needs to be done to obtain requested results. All results are presented by 3D, 2D graphs and tables and compared with analytical results or results from other authors. Although is this publication focused on numerical modeling using FEM, hole-drilling method has many significant restrictions. The most substantial of them is influence of eccentricity of drilled hole, creation of stress concentration near drilled area and subsequent plastification, influence of geometrical inaccuracy of hole, etc. All these aspects have significant influence of determining calibration coefficients and can not be included into numerical simulation. These problems are closely discussed in background research. All obtained results should be helpful for practical use of calculated calibration coefficients to determine uniform residual stresses of specimens with various thickness and drilled hole. All these results are also applicable only for one type of strain gauge rosette, which is RY 61 S.
143

Návrh a optimalizace prostoru hydrostatické kapsy / Design and optimization of hydrostatic pocket space

Minář, Petr January 2011 (has links)
This diploma thesis deals with an optimization of hydrostatic slide of the large-portal gantry machine FRU (TOS Kuřim). First part of the thesis concerns with an analysis of the current practice in hydrostatic guides in the field of heavy gantry machines, an usage of alternative materials for a construction of carrying parts of machines, and possibilities of current simulation methods. Aim of the second part of this thesis is a brief clarification of the principle of mathematical optimization, and creation of general methodology of construction optimization by means of system analysis. Optimization calculations were processed by ANSYS Workbench 11.0. There is achieved adjusted and optimized design of the hydrostatic slide as the result of the thesis. Moreover, the comparison of key deformations was added. Created methodology is applicable in both an area of construction of gantry machines, and a wide spectrum of construction fields.
144

Řešení montážních deformací bloku motoru / Solution of Engine Block Deformations during Assembling

Foltis, Aleš January 2012 (has links)
Size and distribution of mount deformation are the main topics discussed in this thesis, using different static loading. The thesis’ primary focus is to show how deformation and stress of the engine block with cylinder liner are affected in the assembly order of the cylinder head. The calculation and evaluation of the solution are calculated by using method finite element, software Ansys. In addition other methods are discussed which can also measure the deformation of the engine block.
145

Pevnostní kontrola zařízení Vodní výklopník a optimalizace jeho konstrukčního řešení / Design optimisation and strenght checking of Water tiltable devices

Mach, Jan January 2013 (has links)
This master’s thesis is about possibility of fruit and vegetable process from agricultural raw material to food. The first part of thesis include information about machinery, devices and process line and describe how this devices work. The second part solve water tiltable device, this part explain what water tiltable device do, how work and describe structure of each subassembly. Next step solve the device by kinematics aspect and aspect of load analysis. Calculation is included in annex one. Results of annex one are used for FEM (finite element method) simulation of frame. Output of FEM simulation can be used for finding safety factor of displacement and strain, output data are used for optimization of device.
146

Identifikace parametrů elasto-plastických modelů materiálu z experimentálních dat / Parameter Identification for Elastic-plastic Material Models from Experimental Data

Jeník, Ivan January 2015 (has links)
This master's thesis deals with the identification of the material flow curve from record of tensile test of smooth cylindrical specimen. First, necessary theory background is presented. Basic terms of incremental theory of plasticity, tensile test procedure and processing its outputs are described. Furthermore, possibilities of mathematical expression of the elastic-plastic material constitutive law, thus mathematical expression of the material flow curve itself. Mechanism of ductile damage of material is explained briefly as well. Overview of recent methods of the flow curve identification is given, focused on cases, when the stress distribution in a specimen is not uniaxial. That is either kind of analytic correction of basic formulas derived for uniaxial stress state, or application of mathematical optimization techniques combined with numerical simulation of the tensile test. Also unusual method of neural network is mentioned. For 8 given materials, the flow curve identification was performed using different methods. Namely by analytic correction, optimization, sequential identification and neural network. Algorithms of the last two methods were modified. Based on assessment of obtained results, application field and adjusting the parameters of single algorithms was recommended. It showed up, that an effective way to the accurate and credible results is the combination of different methods during flow curve identification procedure.
147

Modelování postkritických stavů štíhlých konstrukcí / Modelling of postcritical states of slender structures

Mašek, Jan January 2016 (has links)
The aim of the presented thesis is to create a compact publication which deals with properties, solution and examination of behavior of dynamical systems as models of mechanical structures. The opening portion of the theoretical part leads the reader through the subject of description of dynamical systems, offers solution methods and investigates solution stability. As the introduction proceeds, possible forms of structure loading, damping and response are presented. Following chapters discuss extensively the possible approaches to system behavior observation and identification of nonlinear and chaotic phenomena. The attention is also paid to displaying methods and color spaces as these are essential for the examination of complex and sensitive systems. The theoretical part of the thesis ends with an introduction to fractal geometry. As the theoretical background is laid down, the thesis proceeds with an application of the knowledge and shows the approach to numerical simulation and study of models of real structures. First, the reader is introduced to the single pendulum model, as the simplest model to exhibit chaotic behavior. The following double pendulum model shows the obstacles of observing systems with more state variables. The models of free rod and cantilever serve as examples of real structure models with many degrees of freedom. These models show even more that a definite or at least sufficiently relevant monitoring of behavior of such deterministic systems is a challenging task which requires sophisticated approach.
148

Dynamická analýza lehké mostní konstrukce / Dynamic analysis of lightweight bridge construction

Krzywoň, Filip January 2016 (has links)
The thesis compares the dynamic response of lightweight footbridge structure. Two finite element models were made. One in Ansys 15.0 software, and another in RFEM 5.05 structural software. The results of the models were compared to each other. The response to dynamic excitation from pedestrians was evaluated in accordance to ČSN EN 1990/A2.
149

Studie vlivu úprav konstrukce panelové budovy / Study of Influence of Structure Changes of Panel Building

Malý, David January 2016 (has links)
This thesis deals with influence on structure changes of panel building. It is about type B70/R, to which was collected necessary design documentation. Static analysis is performed by ANSYS software. 29 models was created to focus on stress and displacements. Verification of selected wall according to Eurocode is also included.
150

Optimalizace konstrukce saní CNC horizontálních vyvrtávacích strojů / Optimizing design of the slide CNC horizontal boring machines

Valenta, Tomáš January 2016 (has links)
This master's thesis deals with proposals for solutions to increase the stiffness of the slide for CNC horizontal boring standing in order to optimize the design of the slide. Selected problem was solved by sensitivity analysis using desegin of experiment in conditions of linear regression analysis. Data for the sensitivity analysis were obtained by using computational modeling using finite element method. The solution provides a view of the degree of influence on the deformation of the examined elements of the slide. Based on these results were selected elements with the greatest influence and created three ideological designs for improvement. Of these designs, was chose an optimal variant by PATTERN method acoording on the technical, economic and technical-economic aspect. This work offers a new look for the innovating the design to increase rigidity.

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