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Stress-strain analysis of the LKDS800 frame
Tománek, Jiří ; Vlk, Miloš (referee) ; Vosynek, Petr (advisor)
This diploma thesis deals with frame of the two-point crank press LKDS800, which was designed by company ŽĎAS a.s. Frame is welded construction creating the base of the press which has mass approximately 90 tonnes. Aim of this study was to perform strain-stress analysis of the frame. From obtained results perform optimization of mass this frame leading to reduce material costs and machining. In the process is frame loaded by nominal forces from the shearing process, under its own weight and inertia forces caused by moving components. As a result of the dynamic loading in welded joints there are risks of fatigue fracture. The manufacturer of the press is required to find the most loaded welded joint and it to assess the fatigue life.
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Design and realization of measuring device for determination of human arm force depending on elbow joint angle.
Zezula, Miroslav ; Vlk, Miloš (referee) ; Krejsa, Jiří (advisor)
The goal of this bachelor’s thesis is design and realization of measuring device for determination of human arm force depending on elbow joint angle. Used measuring method allows to measure this relationship during one continuos movement from one limit position to another. Simplicity of single measurement run allows to obtain a large set of values and evaluate it statistically. This thesis contains a detailed technical description of the measuring device. Actual force and position of hand are measured by electric transducers. Measured values are captured using Spider8 data acquisition system. Based on experiences from first test measurement, the measuring device is modified and drive unit is added. This drive unit is automatically started by a signal from data acquisition system.
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THE UNCERTAINTIES DEFORMATION AND STRESS USING THE STRAIN GAUGES
Dokoupil, Pavel ; Vlk, Miloš (referee) ; Koška, Petr (referee) ; Habán, Vladimír (advisor)
The dissertation thesis deals with the determination of uncertainty of strain measurement and the stress using resistance strain gages. You can find two methods to define the uncertainty in the thesis, GUF and MMC, and both are applied for measurements carried out with resistance strain gages. Definition of the measurement uncertainty was set for the strain measured by uniaxial and biaxial strain gages. The uncertainty of the stress was defined for linear strain gages, T Rosettes and Rosettes. There were universal mathematic-technical models defined to measure strain and stress, these models can be used either for standard and special measurements i.e. high-temperature, or for measurements in radiation field. Each part of the strain uncertainty and stress is analyzed from the point of view of a size of uncertainty and a form of probability of the function that strain and stress can adopt. The maximum focus was dedicated to the mistakes influencing measured strain like strain gage properties, installation and operating influences, external influences, time effects and the influence of the measured object. There are two mistakes influencing the stress described and analyzed in the thesis, the mistake of the Young’s modulus of elasticity and the mistake of the Poisson’s ratio. The thesis is conceived as a complex of information related to the measurement uncertainties using the resistance strain gages and methods of defining the measurement uncertainty in a way that the experimenter can apply the gained info and methods in the required measurements. The final chapters give representative examples to define measurement uncertainties for uniaxial and biaxial stress applying GUF and MMC method. The thesis also includes the experiment that compares measured values of strain, stress and measurement uncertainties, using several different types of strain gages at different temperatures, with theoretical calculation of strain and with stress. The experiment was carried out using the displacement sensor that works on an elementary principle of bending load.
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Comparison of strains determined by finite element method and by optical measurement system
Zajíček, Vít ; Hlavoň, Pavel (referee) ; Vlk, Miloš (advisor)
This thesis focuses on the comparison of numerical simulation and optical measurement of deformation of the turbinehousing made by Honeywell company. The numerical calculation performed by finite element method to simulate transient thermal load on the measured entity. Numerical result of the strain state of the body caused by temperature gradients. To verify the simulation is used an experimental digital correlation method VIC-3D. The thesis also mentioned the theoretical foundations of digital correlation methods and thermal analysis.
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Analysis of load capacity of selected welded structural joints under static and cyclic load
Peč, Michal ; Vlk, Miloš (referee) ; Vosynek, Petr (advisor)
Welding is a widely used method of connecting components because of its efficiency, great value and almost endless possibilities of join types. A great variability of geometrical configurations of welds is problematic due to the assessment of the weld joint. Depending on this topic this thesis was focused on the assessment of weld joints statically and cyclically. Work in the first part deals with the search of methods for evaluation of welds and depending on identified options is subsequently selected American standard AISC assessment of welded joints. The method is applied into FEA analysis and simple welded joints are evaluated. Using FEM are computed three examples on which a comparative analysis was performed. Comparisons were made with the analytical solution based on changes in the parameters of the computational model. The change is primarily related to material properties, mesh size and division of the weld on segments. On the basis of knowledge from analysis of simple joints, method was extended to more general welded joints with the possibility of determining the maximum loading force.
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Design of the computational lifetime prediction methodology for the roll bearing
Vaculka, Miroslav ; Vlk, Miloš (referee) ; Vrbka, Jan (advisor)
This master’s thesis deals with a fatigue analysis of a roller bearing. The fatigue analysis consists of determining service-life of a roller bearing using a stress-strain analysis with finite element method and subsequent numeric calculation using software fe-safe with application of Brown-Miller multiaxial fatigue criterion. Service-life of a roller bearing is determined by number of cycles to failure in the form of pitting formation which is consequence of contact fatigue. According to calculations was found an inappropriateness of Brown-Miller criterion for high-cycle contact fatigue. Test of other available criteria was performed. Principal-Strain criterion provided the best match with ISO 281 standard.
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Comprehesive Theoeretical Analysis of Ring-Core Method for Residual Stress Determination
Civín, Adam ; Holý, Stanislav (referee) ; Plánička, František (referee) ; Frydrýšek,, Karel (referee) ; Vlk, Miloš (advisor)
Comprehensive analysis of the ringcore method used for the determination of the residual stresses in mechanical components is presented in this thesis. Principles, advantages, disadvantages and applicability of this semidestructive experimental method are discussed too. At the same time the ringcore method is compared with the hole drilling method, which is used more frequently. All aspects of the ringcore method are analyzed by the finite element method. FE simulations, performed on the universal numerical model, verified principles of the integral method and the incremental strain method. FE simulations also provided basic information for the uncertainty analysis, which significantly affects the accuracy of the residual stress measurement. The main goal, which the present work deals with, is to create a global overview of all ringcore methods´ aspects elaborated in a clear and complex form.
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Evaluation of Financial Situation in Selected Corporation
Urbanová, Dagmar ; Vlk, Miroslav (referee) ; Zemánková, Lenka (advisor)
The thesis deals with Evaluation of the Financial Situation of the Selected Company through indicators of financial analysis. First part of this thesis is focus on theory, therefore to defined the basic concepts and desribed the various methods indicators necessary for the processing of financial analysis. Then financial analysis is being carried out according to mentioned indicators for the years 2011 - 2015. At the end of this thesis are new measures, which will help to improve the identified problems.
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