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Influence of underground installation conditions on crack propagation in polypropylene pipes
Tesař, Jakub ; Gratza, Roman (referee) ; Hutař, Pavel (advisor)
The thesis addresses the issue of buried polymer pipes and the impact of installation conditions on their lifetime. Based on data obtained from standards, the values of external loads acting on the polymer pipe are determined. To apply these values in numerical calculations, the conversion of individual load components is also provided. Various stress values, simulating different burial installation conditions, are applied to a 2D model. The numerical calculation of the 2D model includes the progression of tangential stresses and their comparison with the standard. Furthermore, the influence of installation conditions on the burial depth of the pipe is analyzed. The comparison of models is conducted for both 2D and 3D models against the standard. The comparison verifies that the models are equivalent and closely correspond to the basic calculations according to the standard. The 3D model is then extended to include a crack, and the propagation through the pipe wall under the most critical load conditions is modeled. The concept of linear elastic fracture mechanics is used to estimate the lifetime of the pipe.
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Calculation of the temperature field of an asynchronous motor
Pavlásek, Ondřej ; Mach, Martin (referee) ; Janda, Marcel (advisor)
This bachelor's thesis focuses on thermal calculations of an asynchronous machine. The first part of the thesis addresses the issues related to the asynchronous motor and the occurrence of losses. The next section is dedicated to the thermics of electrical machines, heat, and cooling. Subsequently, a temperature distribution calculation was performed on the TM90-4S motor using the Motorcad program, and these results were compared with measurements on the machine.
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Design of the connection of the friction pad and the outer ring of the clutch bearing
Kopytko, Alexandr ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis focuses on the design of the connection between the friction pad and the outer ring of the clutch release bearing. During the assembly of the friction pad, occasional damage occurs, leading to material degradation and production delays. Given the wide range of polyamides used in this application, the research includes an overview of these materials, their modifications, and methods for joining plastic with metal. The friction pad represents a further step in the improvement of the clutch mechanism; thus, the research also covers the single-plate friction clutch and its development. The connection between the friction pad and the bearing is implemented using clips that ensure a firm mechanical bond. The analysis employs the finite element method (FEM) in Ansys Workbench, utilizing 3D geometry from Creo Parametric. Based on the stress-strain analysis, design modifications of the clip connection were proposed. The outcome of the thesis includes two new models of the friction pad and their modifications, with clip dimensions approaching the manufacturability limits. The conclusion of the thesis compares the newly developed models with the commercially available design, proposing manufacturability and assembly procedures. This comprehensive approach ensures that the new design solution is not only technically feasible but also can be economically viable and practically applicable in industrial production.
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Stress and strain analysis of ulna bone with plate
Šafran, Jindřich ; Burša, Jiří (referee) ; Marcián, Petr (advisor)
A fracture of the elbow joint represents a serious pathological injury. In simple cases, if it is~possible the injury can be treated without invasive surgery. In the case of more complex fractures - comminuted fractures, it is necessary to have invasive surgery and the incriminated area must be reinforced with fixation splints. The present study focuses on~performing a~strain and stress analysis of the proximal ulna, which is fixed with~a~specialized titanium splint. To assess the mechanical interaction between the elements of the system computational modelling using the finite element method was used. In the first part of the study, the orthotic investigation is focused on types of ulna fracture, including its fixation, which is complemented by an anatomical search. In the second part of the thesis, the emphasis is placed on the creation of a geometry model from the received CT data, including its~modification for the creation of a computational model. Based on the available search material models were selected or calculated. In the third part of~the~thesis, the focus is on the complex development of the computational model, including constraints, placement of muscle tendons and it also focuses on the description and consideration of the choice of computational model options. In the results presentation the effects of the identified variants of the computational model were assessed as a function of load and the strain and stress characteristics were plotted. The assessment also emphasized on the mechanical interaction between the~mechanical elements of the fixation splint and screws with the bone tissue.
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Comparison of approaches to the assessment of buckling of variously long and supported columns
Ostratická, Klára ; Pokorný, Jan (referee) ; Šebek, František (advisor)
The bachelor's thesis deals with assessment of the buckling stability. The differences between elastic and inelastic buckling and effects on the critical force are described. The effect of material, supports and length of the column is described in more detail. During buckling, the character of deformation changes, the compressed column starts to bend at a definite point. This point is called bifurcation point and the limit is amount of critical force. The calculation of critical buckling force is carried out analytically for selected examples using the Euler and Johnson methods. The results are numerically checked by the finite element method in Ansys. The results for linear buckling are identical. Examples of nonlinear buckling are also calculated numerically. The difference is found in critical force for contact surfaces without friction and with friction. Defining the critical force can prevent the collapse of the entire structure, thus avoiding catastrophic incidents.
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Stress analysis of the only extant pier of the former Ivančice viaduct
Pelaj, Jakub ; Fuis, Vladimír (referee) ; Vaverka, Jiří (advisor)
The bachelor thesis focuses on the stress analysis of the original Ivančice viadukt pillar. The introductory part describes the theoretical basis necessary for the analysis. The second part deals with the history and assembly of the bridge. The third part dedicates to the creation of three-dimensional structure which serves as a basis for conducting the stress analysis. The following part provides a detailed expanation of the solution process and analytical calculations itself. In the conclusion, the obtained results are verified using numerical calculations a supplement with partial results concerning an additional type of load.
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Stress-strain analysis of cementless femoral stem in total hip arhtroplasty
Čáp, Lukáš ; Borák, Libor (referee) ; Marcián, Petr (advisor)
This master thesis focuses on the issues related to uncemented total hip replacements. The long-term functionality of uncemented implants is significantly influenced by their postoperative (primary) stability. This thesis analysed the influence of the placement of the implanted stem in the femur and the density of the cancellous bone tissue on the strain – stress states of the total hip arthroplasty system during primary stability. Computational modelling using the finite element method was used for the analysis. First, selected sections of anatomy and hip replacements were presented. Then, a literature review related to the solution and evaluation of strain-stress states was made. The total deformation of the system, the equivalent stress according to the HMH criterion in the stem, the overloading of bone tissues according to Frost's hypothesis, and the relative displacement between the stem and bone tissues were analysed for the options of the computational models. The density of the cancellous bone tissue and the method of stem placement affected the magnitude of these variables. The option in which the stem was most in contact with the compact bone tissue resulted in the least overloading of the cancellous bone tissue. The density of the cancellous bone tissue significantly influenced not only its overloading but also the relative displacement between the stem and the bone tissue.
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Strength analysis of hydraulic equipment construction
Burian, Martin ; Klezla, Vojtěch (referee) ; Zeizinger, Lukáš (advisor)
This thesis deals with the strength analysis of two tanks of hydraulic power units using finite element method. Introduction consists of a brief description of these units and description of a current solution. An analysis of force effects and load conditions follows. The next part describes the calculation model and then the calculation results. Based on these results to improve mechanical properties, a proposal is made. The attachment of this thesis is drawing documentation. The thesis was created in cooperation with Bosch Rexroth, spol. s r. o.
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A simplified model of the pad deformation of the journal bearing
Janiš, Tomáš ; Cabaj, Gabriel (referee) ; Pokorný, Jan (advisor)
The presented bachelor thesis deals with the calculation of deflection of a pad of a hydrodynamic radial bearing with tilting pads. This type of bearing is described by its characteristics, which are determined by means of simulations. Knowledge of these characteristics is important for predicting the behaviour of bearings in service and for the design of equipment using these bearings. The bearing characteristics are strongly dependent on the thickness of the lubricating film. This is in fact very thin and is therefore affected by the slightest deflection of the pad. This paper therefore deals with the calculation of pad deflection. With this calculation, the effect of pad deflection can then be included in downstream simulations to determine the bearing characteristics. The inclusion of this effect results in more accurate simulations. For this reason, a computational model of bearing pad deflection is developed. This model is based on the differential equation of the deflection line assuming small deformations. The temperature effects due to lubricant heating and the pressure effects due to bearing pad loading are included in this calculation. The deflection results from these loads are further compared with the results obtained by the finite element method. This comparison did not achieve the required compliance.
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Sensitivity analysis of FE model of a crash test
Jančář, Radek ; Řehák, Kamil (referee) ; Dlugoš, Jozef (advisor)
The deformation of the vehicle as a result of the accident serves as the input for determining the impact speed for the purposes of the expert report. One possibility of calculating the impact speed is by means of a verified finite element analysis (FEA) of the vehicle impact. However, to develop such a sufficiently accurate finite element model requires a significant financial and time investment. Such a model contains a number of key simplifications that are difficult to detect without prior experience. Fortunately, there are at least a few freely available detailed finite element (FE) vehicle models that have been experimentally verified. On these it is possible to investigate the effect of different modelling methods on observed parameters such as overall deformation or overall vehicle stiffness. Specifically, this thesis investigates the effect of geometric resolution level details, material model parameters, and boundary condition settings for the FE model of the Chevrolet Silverado 1500, model year 2014.
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