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A review study of metamaterial structures for applications in implantology
Tonhajzer, Michal ; Lošák, Petr (referee) ; Marcián, Petr (advisor)
This bachelor thesis deals with the influence of geometrical parameters variation on the stress-strain states and elastic characteristics of auxetic meta-materials. The research part of the thesis summarizes the basic properties of materials, methods of their determination, specifics in the response of auxetic meta-materials to external loads, occurrence and different types of auxetic structures. The next part of the thesis is devoted to the potential use of auxetic meta-biomaterials in implantology. In the computational part of the thesis, a parametric computational model of a particular auxetic meta-material structure was developed, on which a stress-strain analysis was subsequently performed and the influence of changing geometrical parameters on the material mechanical properties, stress and strain was assessed. Based on the results, two structures were created with parameter combinations chosen to eliminate undesirable effects while maintaining the desired properties. A detailed stress-strain analysis was performed on these two structures and the results were compared with a reference structure. Computational modelling was carried out using the finite element method in ANSYS Workbench 2023 R2.
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Evaluation of stress and deformation of a bimetallic beam under changed temperature
Jurkovič, Vítězslav ; Horníková, Jana (referee) ; Burša, Jiří (advisor)
This bachelor’s thesis deals with stress-strain analysis of a selected bimetallic strip. First, a literature search is carried out on used bimetallic strips, including introduction of used materials and criteria for their selection. Next, an analytical calculation of free deformation of the strip at the chosen temperature is performed using rod assumptions. The following is a comparison with the results obtained using finite element method in the Ansys Workbench system. The analysis of the same strip with limited deformation is then performed using the finite element method. In this way, a stress analysis of the complete deformation constraint is performed first, including verification of the results using substitute of the deformation boundary by a force one. The following is a deformation analysis when the deformation is constrained by the selected valve spring with existing clearance, including the determination of the compression of spring. The outputs of this thesis are the results of the free deformation of strip at given temperature change, the analysis of the resulting stresses in strip due to the constrained deformation and the calculation of compression of valve spring at temperature changes.
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Engineering optimization of the pressing process of the turbo molecular pump rotor
Baklík, Jiří ; Čekán, Václav (referee) ; Vosynek, Petr (advisor)
This thesis deals with the issue of press fitted joints and the optimization of the rotor pressing process of the mechanical turbomolecular pump nEXT300T. The press fitted assembly consists of three main parts (blade discs, hollow shaft, main shaft). The blade discs are press-fitted onto the hollow shaft, then this assembly is press fitted onto the main shaft. The optimization was performed by computational modeling based on the finite element method, using ANSYS Mechanical 2024 R1. The pressing process has been optimized to reduce production costs. The assembling process is more expensive due to liquid nitrogen, which is currently used for cooling the press fitted parts. Design of the pressing temperatures was carried out. For heating a temperature of 130 °C was determined. For cooling a temperature of-65 °C was chosen, this can be achieved using an industrial freezer. Due to the change in pressing temperatures, tolerance fields of the components were designed to ensure that the assembly can be assembled and that the press joint will not be lost under operating load. For the connection between the blade discs and the hollow shaft, a radial interference of 0,0585-0,0695 mm is required for functionality. For the connection between the hollow shaft and the main shaft, a radial interference range of 0,01-0,02 mm is functional.
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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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A review study of dental mini-implants
Pernický, Vojtěch ; Hrubanová, Anna (referee) ; Marcián, Petr (advisor)
This thesis focuses on the study of dental mini-implants, which are becoming a popular choice for replacing missing teeth and retaining overdentures. The insertion of mini-implants is a less invasive procedure that minimizes damage to bone tissue, which shortens the patient's recovery time. One of the key advantages is the possibility of immediate loading of the implant. However, the smaller diameter of these implants means a smaller surface area for osseointegration, which can negatively affect their stability and functionality. This thesis deals with the analysis of deformation and stress states by using computational modeling. The results of this analysis are compared with standard implants to evaluate the mechanical behaviour of mini-implants and their interaction with bone tissue. Based on the results of the analysis, it can be said that the diameter of the implant significantly influences its deformation-stress states.
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Stress-strain analysis of hip spacer
Janáčik, Lukáš ; Valášek, Jiří (referee) ; Marcián, Petr (advisor)
This thesis focuses on the stress-strain analysis of the hip joint with a spacer using computational modelling in the form of the finite element method in ANSYS Workbench. The thesis also includes a review of available literature and a brief evaluation of its contributions to the issue. Computational models were created for five variants of geometries of spacers, two different material models of the spacer cores, and two material models (homogeneous and non-homogeneous) of the cancellous bone tissue. The bone cement was evaluated against the limit of brittle strength using the Mohr-Coulomb criterion, which considers different allowable stress values in tension and compression. Core of the spacer was evaluated against yield strength of a material and bone tissue was compared to allowed value of stress intensity before its fracture. The maximum load that the system with a given spacer variant can carry before reaching the first and second limit states was evaluated. Based on the results, it can be determined that the highest load is carried by the intraoperative spacer V2 with either a titanium or steel core, or without a core.
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Stress-strain analysis of skull implant with fixators
Machala, Karel ; Votava, Tomáš (referee) ; Marcián, Petr (advisor)
A skull implant with fixators is used for the reconstruction of a damaged area of the skull, where a defect has occurred due to traumatic injury or disease. Nowadays, the production of a skull implant is preoperatively planned and employs modern technologies to achieve a patient-specific, customized approach. However, the manufacturing process of accurately fitting skull implants is associated with the challenge of achieving geometric precision and potential complications. The mechanical behaviour of the skull implant within the defect is a crucial factor that influences its functionality. This bachelor's thesis presents a comparison of distinct models of skull implant geometry at the interface between the implant and bone tissue, based on stress-strain analysis. Stress-strain states are determined using computational modelling utilizing the finite element method. Three variations of skull geometry models with the skull implant, considering different interfaces between the implant and bone tissue, were analysed. Additionally, for result comparison, a reference model of a skull without a defect was solved and analysed. The values of implant displacement were higher in cases where a gap was created at the interface between the implant and bone tissue. The stress values on the fixators were higher for the model variations with a gap created at the interface between the implant and bone tissue.
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Stress-strain analysis of the process of continuous steel casting
Cabaj, Gabriel ; Petruška, Jindřich (referee) ; Návrat, Tomáš (advisor)
The thesis is focused on the development of a computational model for determination of stress and strain of a round billet in the process of continuous steel casting. The supplied material characteristics, the geometry of the continuous casting machine and the temperature distribution in the billet are applied as input data for stress and strain analysis. The computational model based on the finite element method is developed in the commercial software ANSYS. The thesis can be divided into three parts. The first part includes background information related to the continuous casting of steel and a research analysis of the computational modeling of this process. The second part describes the development of the planar and three-dimensional computational model in detail. Finally, the obtained stress and strain results are analyzed and general conclusions, and recommendations for further development are proposed.
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