|
|
Computational analysis of cross roll straightening of rods
Štourač, Vít ; Šebek, František (referee) ; Petruška, Jindřich (advisor)
Today is on products from the perspective of quality placed an increasing emphasis. This work is focused to the analyze of cross roll straghtening of long semifinished products with a circular cross-section. This process increased quality of semifinished products from the perspective of their curvature, because they do not reach the required limit values. Curvature of the semifinished product is due to residual stress, which is during straghtening using plastic deformation of the material redistributed and the semifinished product is leveled. This work analyzes the effect of rotation of straightening rolls on the distributiom of contact pressure between the straightening semifinished product and the roll of straightener. Author then analyzes effect of input parameters of program to straightening at the final curvature of the semifinished product. With the experience gained, then try to adjust some input parameters.
|
|
|
Mechanical Analysis of the Influence of Fabrication Tolerances on Contact Conditions between the Acetabular Cup and the Femoral Head in Total Hip Replacement
Koukal, Milan ; Horyl, Petr (referee) ; Repko, Martin (referee) ; Janíček, Přemysl (referee) ; Florian, Zdeněk (advisor)
In endoprosthesis surgery there are typically a high percentage of implant defects, these can lead to failure of the whole prosthesis. One type of total hip replacement function loss is acetabular cup loosening from the pelvic bone. This disertation examines manufacture perturbations as one of the possible reasons for this kind of failure. Both dimension and geometry manufacturing perturbations of ceramic head and polyethylen cup were analyzed. We find that perturbations in the variables analysed here affect considered values of contact pressure and frictional moment. Furthermore, contact pressure and frictional moment are quantities affecting replacement success and durability. From obtained results it can be recommended to fit head and cup with a clearance of between 0 mm and 0.05 mm. It can not be recommend using interference type of fit because of strong deterioration of the contact conditions. Roundness perturbation of ceramic head should not exceed 0.025 mm.
|
|
|
Analysis of vibratory roller with new type of steering kinematics
Votroubek, Jan ; Rada, Zdeněk (referee) ; Škopán, Miroslav (advisor)
Diploma thesis includes design of bearings of steering joints of tandem vibratory pivot-steering roller Ammann AV 95-2, design of bearings of steering joints of tandem vibratory with new type of steering kinematics and calculation and comparison of contact pressures between drum and soil for different angles of turn of front and rear drum for different types of tandem vibratory rollers. Comparison of contact pressures is realised for pivot steering roller AV 95-2, articulated tandem roller AV 80 X, articulated tandem roller with modified configuration of steering-joints and tandem roller with new type of steering kinematics.
|
|
|
Sliding and Lifting Platform
Kučo, Stanislav ; Suchomel, Petr (referee) ; Škopán, Miroslav (advisor)
This thesis describes a project of a mobile stage device that will be used for a concert tour of Lucie. The first part characterizes the given task and expounds description and function of the device itself. The second part focuses on the design concept of supporting frames. This is followed by design and calculation of all mechanisms, actuators and construction of individual moving parts of a sliding and lifting platform. The last part verifies stability of the whole construction in accordance with appropriate standards. The thesis also contains technical documentation, which is to be found in appendix.
|
|
|
Thermal contact resistance of planar surfaces
Mateášik, Timko Marek ; Horák, Marek (referee) ; Mašek, Jakub (advisor)
Bakalárska práca rieši tepelné prechodové odpory rovinných povrchov v kontakte pre účely projektu tepelného spínača. Zameriava sa hľadanie vhodného matematického modelu na predikciu tepelných prechodových odporov ako možného riešenia pre optimalizáciu tepelného spínača. Práca sa skladá z teoretickej a praktickej časti. Teoretická časť stručne uvádza pozadie projektu a dôvod vzniku tejto práce. Ďalej rieši ako sú tepelné prechodové opdory denované a faktory, ktoré ich ovlivňujú. Následne uvádza prehľad existujúcich modelov na predikciu tepelných prechodových odporov, vhodnú selekciu modelov pre možné použitie a ich popis. Praktická časť sa zaoberá návrhom a výrobou medených vzoriek pre experimentálne merania, ich následnými úpravami a povrchovými meraniami. Ďalej rieši spôsoby merania, podmienky merania a samotné merania tepelných prechodových odporov. Za použitia modelov z teoretickej časti sú vykonané teoretické merania a za použitia testovacej komory experimentálne merania. Merania sú navzájom porovnané. Na základe výsledkov z meraní sú urobené úsudky, ktoré budú požité v budúcnosti pri vývoji vesmírnych komponentov.
|
|
|
Design of a test condition for determining the wear at the contact of a railway wheel and rail
Rec, Matouš ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This diploma thesis focuses on the issue of a wear of a railway wheel and a rail. The wear of the components depends on a number of parameters including the contact stress, the contact pressure and the contact surface dimensions. Among the factors determining these parameters belongs primarily the wheel driving gauge, the rail profile and the load of the contact area. Furthermore, the material from which the wheels and rail are made, the roughness and hardness of the functional surfaces and the residual stress in the material have a significant impact on the wear. All the parameters mentioned above are designed for the production of the railway wheels and rails and therefore they meet the standards for the production of these components. However, the existence of the changeable parameters has also a significant impact on the wear. These parameters include the presence of contaminants, or lubricants in contact, the changing driving gauge due to the wear, the slip ratio or the friction coefficient. With the wear being an inevitable process during the application it cannot be eliminated but only controlled. Applying the lubricant into the contact when passing through the arc in order to achieve an ideal coefficient or the maintenance grinding for restoring the driving gauge can serve the purpose. If properly optimized, the importance of the wear research lies in the financial savings. Being the crucial factor for optimization of the intervals between the maintenance grinding, the research is also beneficial. A high-quality wear prediction can be seen as the key field in order to increase the safety of the railway vehicles operation as well. Therefore, the wear research is made using several methods, such as the computational models, the multi-body dynamics software and the technical experiments. This thesis introduces a conceptual design of the test, enabling the wear research via experimental approach. The final device is capable of a simulation of both volume and fatigue wear during the states the railway wheel and railway undergo including riding on the straight track, passing through an arc or a wheel slip during braking.
|
|
|
Study of behaviour of EHD lubricated contact of machine parts within non-smooth surfaces
Zapletal, Lukáš ; Maňas, Pavel (referee) ; Vaverka, Michal (advisor)
Master’s thesis deals with development of software application to calculate contact pressure in eleastohydrodynamic lubricated contact in order to use previously obtained data of the lubricating film thickness. The introduction contains a short overview of methods used for the study of film thickness and contact pressure. Custom work includes a contact pressure solution derived from a film thickness, a description of the developed software and analysis of algorithms used for its compilation. The last part deals with the verification of algorithm, application of software for calculating the contact pressure on the rough surface and analysis of the results. The conclusion includes a summary and possible application of software in practice.
|
|
| |
|
|
Biomechanical study of the effect of various leg length to stress skeleton
Novotný, Lukáš ; Marcián, Petr (referee) ; Florian, Zdeněk (advisor)
The key role of this thesis deals with providing light on the influence of unequal length of limbs in particular with legs and the stress it might leave on human body parts, possibilities and ways of its reparation. As per the research conducted in the first chapter which allows to get an insight and summary about the issues and also provides information related to unequal length of lower limbs and hardships involved. The following part explains the basics of anatomy related to unequal length of legs and solution of force interaction in the hip joint. Suitable attention is dedicated to the influence of unequal leg length and equalization of unequal length legs. A separate part of the thesis is devoted to the effect of unequal lower limb on contact pressure between the femoral head and the hip joint. Computational analysis of the contact pressures using final elements method in computing software Ansys Workbench 16.2 proved a negative impact of uneven length of lower limbs to stress on the hip joint.
|
|
|
Calculation of contact pressure from experimentally evaluated lubricant film thickness
Kozel, Lubomír ; Hartl, Martin (referee) ; Vaverka, Michal (advisor)
This diploma thesis is engaged in calculation of contact pressure from thickness of lubricating film using Finite Element Method (FEM). Within my diploma thesis were performed the calculations concerning to non-conformal surfaces with a view to elastohydrodynamic lubrication. The simulations were done for disk and ball contact, respectively with burnished finish and also with surface which contains small dent. Flow diagram was designed so that the creation of geometry, boundary conditions and results saving is controlled parametrically. With using parameters it is possible to repeat the calculation when the resolution, geometry, etc. will be changed.
|
guest ::
