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Residual fatigue life estimation of railway wheelset
Pokorný, Pavel ; Zouhar, Michal (referee) ; Náhlík, Luboš (advisor)
The first part of this master's thesis deals with the high cycle fatigue of materials, especially on growing cracks using linear elastic fracture mechanics. Much of this work is focused on the concept of stress intensity factor. This concept is nowadays one of the most widely used concepts for describing a body with crack. The first part ends with theoretical approaches to determine the residual fatigue life of the body with a crack. The second part of this master's thesis is focused on the determination of residual fatigue life of a specified railway wheelset. An existence of crack-like defect is assumed at the railway wheelset. The goal of this master's thesis is to estimate how long it will take to grow from initial defect to a critical crack length. The last part of this master's thesis is devoted to addiction order load cycles on crack growth rate.
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Secure Company System with a Corporate Social Responsibility Approach
Zouhar, Michal ; Tesař, Rostislav (referee) ; Jurová, Marie (advisor)
The diploma thesis is focused on the emergence of danger at work. Related to this is the identification of risks and their management. It defines all emerging risks and their preventive measures. The main task of this activity is to minimize accidents in the workplace. Subsequently, the current level of occupational safety was assessed using a questionnaire obtained from the State Office of Labor Inspection. The work is divided into 4 categories. The theoretical part of the diploma thesis describes the key concepts that are necessary for the elaboration of a diploma thesis. Terms such as risk, threat, risk identification and risk assesment methods are explained. The conclusion of the theory includes BOZP, work-related injuries and a description of what the Safe Company certification means.The analytical part is an analysis of the current situation, BOZP assessment and risk management analysis of the main production process. The last practical part of the diploma thesis is focused on preventive measures in the main production process using FMEA analysis and proposing BOZP improvements.
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Design of Process Management of a Contract in a Manufacturing Enterprise
Zouhar, Michal ; Šmerda, Josef (referee) ; Jurová, Marie (advisor)
The goal of this thesis is to describe the process management of orders in Araplast company. First part of this thesis is dedicated to the theory. Second part is dedicated to the company called Araplast, to the order of steps during the process of production and also to the technologies that are used during the production of traffic signs. Last part is focused on analysis of production and it is also dedicated to the proposal of improvement.
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Description of Failure of the Multilayer Polymer Structure
Zouhar, Michal ; Klusák, Jan (referee) ; Kučera, Jaroslav (referee) ; Hutař, Pavel (advisor)
The aim of this thesis is to describe behavior of cracks in layered polymer materials. Quasi-brittle fracture (through the initiation and subsequent crack propagation mechanism) under low stresses is the most common mode of failure of polymer materials. In this case plastic deformations are localized in the vinicity of the crack tip and linear elastic fracture mechanics description of the crack behavior can be used. The knowledge of fracture parameters change during the crack propagation in multilayer body is a key point for establishing of the maximum load and consequently for the assessment of the residua lifetime. In contrast to homogeneous bodies the estimation of stress intensity factors for multilayer (composite) structure is numerically more elaborated and the fracture mechanics approach is complicated by the existence of interfaces between single layers, where material parameters are changed by a step. Special attention is paid to the configuration of a crack growing close to the material interface and along the interface. For the crack with tip on the material interface the effective values of stress intensity factor based on the crack stability criteria are estimated. It is shown that under special conditions (depending mainly on the elastic mismatch of materials) the existence of material interface has positive influence on the lifetime of the multilayered structure.
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Grinding Angle Box Unit for Vertical Boring and Turning Machine
Zouhar, Michal ; Kukleta, Pavel (referee) ; Foller, Bronislav (advisor)
My diploma thesis solves project of grinding angle box unit for vertical boring and turning machine which extends technological possibilities of vertical lathe SKD 40/47D. The submitter ČKD Blansko Holding, a.s. demanded to work out assembly drawing, 3 construction drawings and necessary calculations. Spindle drive of grinding unit is implemeted by the aid of engine which is deposit in the sliding machine. Chucking equipment is realised with standart system which is used by ČKD Blansko.
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Stress - strain analysis and creep assessment of the thick-walled tubular structures.
Zouhar, Michal ; Petruška, Jindřich (referee) ; Hlavoň, Pavel (advisor)
This thesis deals with the stress-strain analysis of thick-walled pipe parts. The dimension series (characterized by the D/d ratio) of three components are solved, then a direct tube, a torus with constant wall thickness (arcus) and a torus with variable wall thickness (bend). At first, the internal pressure amount, when a fully plastic state for these components is created, is solved. The amount of the limit pressure is determined analytically, numerically and by appropriate normative relations. The results and stress diagrams of individual solutions are mutually compared. Furthermore, these components are solved in the creep and are exposed to the maximum allowable normative internal pressure for 200,000 hours according to the standard – the operating time of components. The place of the maximum equivalent creep strain and the place of the maximum equivalent stress is examined. In these places the principal stresses are depicted depending on the D/d ratio. The results and stress diagrams of individual dimension series are mutually compared. From the available literary sources the condition of the limit state reach is chosen, according to which the evaluation of the limit state reach for individual components is carried out.
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Compressive testing of pillars: numerical study
Petráčková, Klára ; Zouhar, Michal (referee) ; Náhlík, Luboš (advisor)
Determination of mechanical properties of thin films, which are used e.g. in electronics, is not simple due to the required very sophisticated equipments. Also the interpretation of results is rather difficult. This bachelor’s thesis is focused on determination of important factors which affect the microcompressive testing results. For microcompressive testing, the pillars made from studied thin film attached by the bottom to a substrate are used. There can be another thin interlayer between studied film and the substrate. The pillar is made by focused ion beam (FIB). Pillar is loaded by a nanoindenter with flat tip while the deformation response is measured. The goal of the thesis is numerical simulation (using the Finite Element Method) of the microcompressive testing and determination of individual specific geometric factors of tested pillars on Young’s modulus of the thin film. Data from microcompressive testing of aluminium thin film attached to silicon substrate with tungsten interlayer were available for numerical simulation. We have estimated influence of specific pillar geometry on data using compressive testing and improved evaluation of Young’s modulus. We have presented a recommendation for more accurate evaluation of Young’s modulus determined from experimental data involving inaccuracy following the pillar shape. The results and methods presented in this thesis can be useful in future development of compressive testing technique for determination of mechanical properties of metal thin films.
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Secure Company System with a Corporate Social Responsibility Approach
Zouhar, Michal ; Tesař, Rostislav (referee) ; Jurová, Marie (advisor)
The diploma thesis is focused on the emergence of danger at work. Related to this is the identification of risks and their management. It defines all emerging risks and their preventive measures. The main task of this activity is to minimize accidents in the workplace. Subsequently, the current level of occupational safety was assessed using a questionnaire obtained from the State Office of Labor Inspection. The work is divided into 4 categories. The theoretical part of the diploma thesis describes the key concepts that are necessary for the elaboration of a diploma thesis. Terms such as risk, threat, risk identification and risk assesment methods are explained. The conclusion of the theory includes BOZP, work-related injuries and a description of what the Safe Company certification means.The analytical part is an analysis of the current situation, BOZP assessment and risk management analysis of the main production process. The last practical part of the diploma thesis is focused on preventive measures in the main production process using FMEA analysis and proposing BOZP improvements.
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Design of Process Management of a Contract in a Manufacturing Enterprise
Zouhar, Michal ; Šmerda, Josef (referee) ; Jurová, Marie (advisor)
The goal of this thesis is to describe the process management of orders in Araplast company. First part of this thesis is dedicated to the theory. Second part is dedicated to the company called Araplast, to the order of steps during the process of production and also to the technologies that are used during the production of traffic signs. Last part is focused on analysis of production and it is also dedicated to the proposal of improvement.
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Pressure pipe damage: Numerical estimation of point load effect
Zouhar, Michal ; Hutař, Pavel ; Ševčík, Martin ; Náhlík, Luboš
The most relevant loading conditions for real polymer pipe systems are not only internal pressure, but also loading caused by sand embedding including bending or different kinds of point loads. It has been shown that service lifetime of buried pipes can be reduced especially due to stress concentration caused by external point loads. If the pipe is loaded locally the stress is concentrated here and a crack can initiate at this position or the existing crack can be affected by corresponding stress redistribution. In the paper the effect of the hard indenter, Poisson's ratio, hoop stress level and pipe wall thickness on the crack shape was estimated using numerical simulations of the creep crack propagation based on finite element method. Relation between crack length and crack width was found and expressed by simple relationship. A deeper understanding of the point load effect in order to prevent unexpected failure of the pipelines is of paramount importance for pipeline design.
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