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Analysis of Reinforced Concrete Beams Subjected to Impact Loading
Dvořák, Tomáš
The utilisation of complex nonlinear material models for concrete in numerical simulations is necessary for the accurate representation of structural behaviour. However, the successful modelling of such complex behaviour depends on a good understanding of the material model parameters. This paper deals with the critical issue of material parameter sensitivity in the context of RC beams subjected to impact loading. The objective was to establish relationships between the material parameters and the responses, including deformations and stresses, using sensitivity. This is the main key to understanding the complex interaction of these parameters and their influence on the structure.
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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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Effect of Velocity of Impact Loading to Stress, Deformation and Durability of Component of Fuel Car System
Dobeš, Martin ; Horyl, Petr (referee) ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
Passive safety is a well-known term. This term can be further categorized into different topics of the car passive safety, restraint systems, safety assistants (ABS, ESP, ASR, etc.). One of these topics is passive safety of the fuel system. Safety and tightness of the fuel system must be guaranteed even under non-standard conditions, for example a collision against a fixed obstacle. This issue is not often mentioned in the field of car safety. It is considered a standard. Passive safety of the fuel system is often ensured using various interesting technical solutions and devices, usually patented ones. The development of these solutions is supported by numerical simulations in different stages of development process. The doctoral thesis deals with impact loading of the plastic components of the fuel system, in particular Fuel Supply Module (FSM), which is mounted inside the fuel tank. The flange is the most important part of the fuel supply module from the car safety point of view. The flange closes FSM on the external side of the fuel tank. The thesis focuses on the finite element analysis of the complete or partial FSM, and the flange itself during impact loading. The main objective of this thesis are numerical material models, taking into account important aspects of the mechanical behavior of polymer materials during impact loading. There are a lot of ad hoc invented or standardized experiments described in this thesis. These experiments are used for estimation of the material parameters or comparison of numerical analysis vs real conditions, or tests. The solver LS-DYNA was mainly used for numerical simulations. The final results of this thesis brings new quantified knowledge about behavior of the Typical Semi-Crystal Polymer (TSCP), not only for impact loading. The practical part of this thesis defines new methodology for the numerical simulation approach of impact loading for FSM. This methodology is directly usable for new product development. A lot of numerical material models were developed and tested. The best results were achieved using numerical material model *MAT_24 with combination of *MAT_ADD_EROSION card. The limits and parameters for this numerical material model was estimated empirically during conducting experiments. The numerical material model SAMP-1 was partly solved in this doctoral thesis, but more detail study will be given in future works.
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Design of auxetic structures for the selective laser melting technology
Pchálek, Václav ; Hutař, Pavel (referee) ; Červinek, Ondřej (advisor)
With the development of additive technologies, it became possible to produce auxetic structures with complicated geometries. Despite their intensive study, their potential for high resistance to local loading has not yet been explored. Describing this phenomenon and its causes would enable the effective design of structures with greatly enhanced resistance to foreign object impact. Therefore, this work investigated the deformation behavior of auxetic re-entrant honeycomb structures under local loading. The relationship between the resistance of the structure to local loading and the magnitude of the negative Poisson´s number, which was controlled by the geometry of the basic cell, was investigated. An analytical approach was used to determine the Poisson´s number of the structures. Subsequently, a prediction of the local loading behaviour of the structures was made using the finite element method assuming small and large deformations. This behavior was then experimentally verified for small and large strain rates on structures fabricated by selective laser melting technology. It was found that for the assumption of small deformations, the smaller the Poisson´s number of the structure, the more resistant it is to local loading. However, this does not apply to the assumption of large deformations, where the wall interaction and its buckling were difficult to predict. Furthermore, structures with thinner walls were shown to deform more, thus using their full deformation potential and therefore being more resistant to local loading. When tested at both low and high strain rates, a rearrangement of the structure towards the impact location was observed in two directions, perpendicular and against the direction of loading. It was found that structures with different geometry but the same Poisson's number have the same deformation behavior in terms of strain rate and reaction force. The findings of this work contribute to the understanding of the behaviour of auxetic structures under local loading, which can be used in the design of such loaded structures in specific applications.
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Numerical Analysis of BFRP Reinforced Concrete Slab Exposed to Impact Loads
Jindra, Daniel ; Hradil, Petr
This paper describes numerical analysis utilizing the FEM of a simply supported concrete slab exposed to close range explosion of TNT charge. Reinforcing bars are made of basalt fibre reinforced plastic (BFRP). 3D numerical model has been created, and a software with explicit solver has been used in order to conduct analyses. A simplified method of the blast loading modelling has been utilized. Several cases with different mesh size or finite element formulation are considered. The results are compared with experimental data.
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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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Effect of Velocity of Impact Loading to Stress, Deformation and Durability of Component of Fuel Car System
Dobeš, Martin ; Horyl, Petr (referee) ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
Passive safety is a well-known term. This term can be further categorized into different topics of the car passive safety, restraint systems, safety assistants (ABS, ESP, ASR, etc.). One of these topics is passive safety of the fuel system. Safety and tightness of the fuel system must be guaranteed even under non-standard conditions, for example a collision against a fixed obstacle. This issue is not often mentioned in the field of car safety. It is considered a standard. Passive safety of the fuel system is often ensured using various interesting technical solutions and devices, usually patented ones. The development of these solutions is supported by numerical simulations in different stages of development process. The doctoral thesis deals with impact loading of the plastic components of the fuel system, in particular Fuel Supply Module (FSM), which is mounted inside the fuel tank. The flange is the most important part of the fuel supply module from the car safety point of view. The flange closes FSM on the external side of the fuel tank. The thesis focuses on the finite element analysis of the complete or partial FSM, and the flange itself during impact loading. The main objective of this thesis are numerical material models, taking into account important aspects of the mechanical behavior of polymer materials during impact loading. There are a lot of ad hoc invented or standardized experiments described in this thesis. These experiments are used for estimation of the material parameters or comparison of numerical analysis vs real conditions, or tests. The solver LS-DYNA was mainly used for numerical simulations. The final results of this thesis brings new quantified knowledge about behavior of the Typical Semi-Crystal Polymer (TSCP), not only for impact loading. The practical part of this thesis defines new methodology for the numerical simulation approach of impact loading for FSM. This methodology is directly usable for new product development. A lot of numerical material models were developed and tested. The best results were achieved using numerical material model *MAT_24 with combination of *MAT_ADD_EROSION card. The limits and parameters for this numerical material model was estimated empirically during conducting experiments. The numerical material model SAMP-1 was partly solved in this doctoral thesis, but more detail study will be given in future works.
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Nondestructive Testing of Heterogenous Materials
Trnka, Jan ; Dvořáková, Pavla
The paper deals with experimental research of stress wave propagation in heterogenous materials. Experimental procedures are focused both on the different techniques of the impact loading and on the different diagnostics methods. The aim of this paper is to optimize loading techniques and diagnostic methods to get the reliable data for computer modeling of structures produced from the heterogeneous materials.
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