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Parameter Identification for Elastic-plastic Material Models from Experimental Data
Jeník, Ivan ; Šebek, František (referee) ; Kubík, Petr (advisor)
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.
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Minimization of residual stresses for rolled long products
Kubík, Petr ; Raudenský, Miroslav (referee) ; Petruška, Jindřich (advisor)
This thesis deals with simulation of cooling of rail during its passing through cooling device which has been designed by the heat transfer and fluid flow laboratory. Inputs of the computational model have been set up to get best possible correspondence between outputs of the computational model and results of experimental measurement. The solution with using of model of austenitic stainless steel is provided in first part of the thesis. The solution with considering model of carbon steel is performed in next part. Using of model of carbon steel allows including evolution of latent heat during phase changing. A fields of residual stress has been calculated for different cooling conditions in the last part of this thesis.
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Design of delivery van.
Kubík, Petr ; Paliatka, Peter (referee) ; Rubínová, Dana (advisor)
The diploma work is aimed at a complex design of a delivery van of the near future. The need for a delivery van to be used as a working tool is constantly evolving. This is namely caused by the expansion of on-line shops & the need to save on running cost of a business. The delivery van is especially designed for use in city traffic. The innovation reveals a single person cabin with panoramatic view, ecological propulsion of the vehicle and the technical solution to the suspension of wheels which allow the turning of all 4 wheels to an angle ranging from -55° to +90°. As a result the vehicle has the ability to perpendicularly drive up to a pavement, fitting in a very narrow space. In addition, it can freely drive forward or backward in a sideway direction. The loading space of the delivery van and its floor is modified as such to allow for one man manipulation, making loading & unloading of goods a simpler task.
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Calculation of natural frequencies of a bar system using finite element method
Svoboda, Petr ; Kubík, Petr (referee) ; Návrat, Tomáš (advisor)
The task of the presented bachelor thesis has been to program an algorithm of the finite element method to calculate natural frequencies of beam systems. To solve this problem a freely available SW products (Python, libraries NumPy, SciPy, Fortran compiler etc.) should have been primarily used and thereby to check possibilities of freely available SW product application in science purposes in the field of the Continuum Mechanics tasks. For a functionality verification of the program the ANSYS code is to be used.
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Stress, deformation and reliability computational analysis of the adjustable tandem trike frame
Ščotka, Martin ; Kubík, Petr (referee) ; Vrbka, Jan (advisor)
This bachelor thesis deals with stress, deformation and safety analyses of adjustable frame of tandem tricycle. Starting with brief introduction of cycling, especially alternative cycling followed by indicating of whip assumptions and computational model of the frame. The final calculations have been done in three basic modes: direct motion, braking and cornering. Inner Stress Resultant has been summed, reduced pressure in a dangerous point has been expressed and safety issue has been figured up as well. Mathematical software MAPLE has been used to solve the assignment. Model is provided in software Autodesk Inventor
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Proposal of a program for solving of problems of simple tension/compression of bars and strut frames
Martínek, Tomáš ; Kubík, Petr (referee) ; Polzer, Stanislav (advisor)
The aim of this work is a program that will solve problems from the simple tension /compression bars and strut frames in the range of bachelor. The work consists of two programs developed in the Borland Delphi development environment. The programs allow the user to define a bar (strut frames) on the basis of the geometrical parameters and constraints, determine the rate of statical indetermination, make the necessary calculations and, if necessary, indicate the condition of deformation (a program for solving bars). The written part of the work serves as a manual.
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