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Increasing the fatigue life of the firearm firing pin using the explicit solver
Adamec, Tomáš ; Petruška, Jindřich (referee) ; Šebek, František (advisor)
Firing pin is a critical component in terms of firearm function. Tip of firing pin can break off due to repeated impact loading, which results in malfunction of the whole firearm. This master's thesis aims to propose changes in geometry of the firing pin so that new firing pin will be more durable against fatigue failure. Geometry and characteristics of the original firing pin are provided by company Česká zbrojovka, a.s. To determine the amount of fatigue damage for specific configuration of firing pin, computational model, which simulates impact loading of the firing pin during dry fire, is created. Finite element method with explicit formulation is used for the calculation. Parameters of geometry, which are assumed to have highest influence on fatigue life, are chosen based on the analisys of the original firing pin. These parameters are changed in further calculations, resulting in new configuration of the firing pin, which is approximately 15 % more durable against fatigue failure.
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Determination of Fatigue Characteristics of Concrete Using Fracture-Mechanics Parameteres
Šimonová, Hana ; Králik,, Juraj (referee) ; Terzijski, Ivailo (referee) ; Bílek,, Vlastimil (referee) ; Keršner, Zbyněk (advisor)
The topic of this PhD. thesis is the issue of determining fatigue characteristics of selected cement-based composites. First, the history of fatigue of metal is mentioned, and some basic notions related to fatigue are clarified. The thesis also summarizes current research in the field of cement-based composites fatigue, and failure mechanisms of plain concrete during static and dynamic tests are described. Furthermore, the thesis deals with the evaluation of static and dynamic experiments’ results with extensive series of C30/37 and C45/55 class concrete specimens. In order to achieve relevant fatigue test evaluation which takes into account the age of the specimens, a new correction procedure of the data measured based on the approximation of the basic fracture-mechanics parameters of tested materials over time was suggested and verified. The annexes of this thesis present complete data obtained during static and dynamic experiments.
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Advance evaluation of fatigue resistance of selected construction materials
Benešová, Anna ; Květoň, Josef (referee) ; Seitl, Stanislav (advisor)
This thesis deals with the analysis of S–N curves of models according to Basquin, Kohout and Věchet and Castilla–Canteli using Weibull and Gumbel solution. These curves are interpolated by measured data of cyclically loaded civil engineering materials like concrete and steel. For each material, the accuracies of individual models are determined and in the conclusion, the suitability or unsuitability of individual models for selected materials is compared and evaluated.
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Analysis of fatigue damage accumulation of test specimens made from S690 and S960
Al Khazali, Mohammad ; Malíková, Lucie (referee) ; Seitl, Stanislav (advisor)
This thesis study and examines the behavior of high strength steels (HSS) during fatigue utilizing S-N curves of models based on the Palmgren-Miner Rule and some invented hypotheses, such as Haibach's model, Corten-Dolan's model and Serensen-Kogajev model. Firstly, a detailed mechanical testing will be done and discussed to ensure creating a proper understanding of the two types of steel that will be the focal point of the research. The curves created are interpolated using measured data form cyclically loaded of the steel to create the relation between the number of cycles the material can withstand before reaching failure state and the level of stress applied on a variety of specimens with different homogenizes but similar characteristics. The accuracy of each model is determined for each grade of steel, the S690 and the S960. Then we will conclude by the end of the work which can be considered suitable and which not of each model and an explanation of the reasoning behind the results achieved to ensure better outcome in future related work.
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Advance evaluation of fatigue resistance of selected construction materials
Benešová, Anna ; Květoň, Josef (referee) ; Seitl, Stanislav (advisor)
This thesis deals with the analysis of S–N curves of models according to Basquin, Kohout and Věchet and Castilla–Canteli using Weibull and Gumbel solution. These curves are interpolated by measured data of cyclically loaded civil engineering materials like concrete and steel. For each material, the accuracies of individual models are determined and in the conclusion, the suitability or unsuitability of individual models for selected materials is compared and evaluated.
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Increasing the fatigue life of the firearm firing pin using the explicit solver
Adamec, Tomáš ; Petruška, Jindřich (referee) ; Šebek, František (advisor)
Firing pin is a critical component in terms of firearm function. Tip of firing pin can break off due to repeated impact loading, which results in malfunction of the whole firearm. This master's thesis aims to propose changes in geometry of the firing pin so that new firing pin will be more durable against fatigue failure. Geometry and characteristics of the original firing pin are provided by company Česká zbrojovka, a.s. To determine the amount of fatigue damage for specific configuration of firing pin, computational model, which simulates impact loading of the firing pin during dry fire, is created. Finite element method with explicit formulation is used for the calculation. Parameters of geometry, which are assumed to have highest influence on fatigue life, are chosen based on the analisys of the original firing pin. These parameters are changed in further calculations, resulting in new configuration of the firing pin, which is approximately 15 % more durable against fatigue failure.
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Determination of Fatigue Characteristics of Concrete Using Fracture-Mechanics Parameteres
Šimonová, Hana ; Králik,, Juraj (referee) ; Terzijski, Ivailo (referee) ; Bílek,, Vlastimil (referee) ; Keršner, Zbyněk (advisor)
The topic of this PhD. thesis is the issue of determining fatigue characteristics of selected cement-based composites. First, the history of fatigue of metal is mentioned, and some basic notions related to fatigue are clarified. The thesis also summarizes current research in the field of cement-based composites fatigue, and failure mechanisms of plain concrete during static and dynamic tests are described. Furthermore, the thesis deals with the evaluation of static and dynamic experiments’ results with extensive series of C30/37 and C45/55 class concrete specimens. In order to achieve relevant fatigue test evaluation which takes into account the age of the specimens, a new correction procedure of the data measured based on the approximation of the basic fracture-mechanics parameters of tested materials over time was suggested and verified. The annexes of this thesis present complete data obtained during static and dynamic experiments.
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The Effect of Overloading of Pipes on their Fracture Toughness in Relation to the Strength Grade of Steel
Šperl, Martin ; Gajdoš, Lubomír
The present experimental results showed a very positive effect of a controlled overloading of a pipeline on its fracture toughness. These results have been referred to steels of the class L360MB and L415MB. However, more recent results obtained on L450MB steel indicated that the positive effect of oveloading is reduced as the strength properties of steels are increased. It follows from this that the final technological operation of overloading of pipes made from steels of an increased strength could be let out from the pipe manufacture scheme. The paper presents experimental results which prove by evidence a decreasing positive effect of overloading on the fracture toughness of steels of high strength properties.
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