Academic literature on the topic 'Dynamická zkouška'

The content of work is to determine modal characteristics of bridge construction over the Dyje river near Břeclav. That is done in ANSYS software and AxisVM software. These characteristics are compared with results from dynamic loading test and they are compared between themselves. In thesis is also an assessment of response to static traffic loads because of decision about dynamic analysis necessity. Then there is a simulation of dynamic traffic loads and results of this simulation are compared with results of dynamic analysis which was done by the project. The aim is to do a few static and dynamic tasks and compare results with the real dynamic test and with calculated results and to determinate the effect on certain variables.

The diploma thesis deals with Formula Student Impact Attenuator design of TU Brno Racing team. The aim of the thesis is the design, the dynamic tests and the production of Impact Attenuator of racing formulas called Dragon 4 and Dragon 5, so to meet the Formula Student rules. The thesis deals further with FEM dynamic analysis of Impact Attenuator.

The theme of this doctoral thesis is research of footbridges curved in plan that are formed by stress ribbon. Recently, several noteworthy curved pedestrian bridges, which decks are suspended on their inner edges on suspension or stay cables, have been constructed. However, curved stress ribbon bridges have not been built so far. The goal of this study was to answer the question whether the use of curved stress ribbon structures is even possible. For this reason, in the first stage feasibility study of these structures has been prepared. Knowledge of both curved pedestrian bridges, which decks are suspended on their inner edge and straight stress ribbon has been used. For the mathematical modeling FEM software ANSYS was used. The obtained findings were further used to design a new type of a modern, aesthetic curved bridge for pedestrians. The structure is formed by slender reinforced deck, which is through the steel brackets on the inner side stiffened by steel section. Torsion of the deck, caused by curved structure and asymmetrical cross-section, is reduced by cable situated in the handrail. Footbridge span is 45 m, arc camber in plan is 10 m, free bridge width is 3 m. Described is a general structure effect, detail static and dynamic analysis was carried out. Designed structure including construction stages were experimentally verified on a fully physical functional 1:6 scale model. The thesis describes the model analogy used for the design of the model, its structural design and its implementation. The model was subjected to a series of load tests including the final ultimate strength test. Performed tests confirmed the good match of calculation with the reality, correctness of the design and high resistance of designed construction. Acquired results and experiences from design and realization of model form the basis for practical realization of studied structures.

This doctoral thesis focuses on the research of the pedestrian bridges formed by the flat arch. To understand the basic static behaviour of the flat arch it was necessary to make a study of the development of the direct flat arch as footbridge with large span and the impact of stiffness on its camber. For the mathematical modeling FEM software ANSYS were used. The calculation has shown that a design of purely concrete flat arch would demand enormous bending stiffness, which can be achieved only through a massive cross-section. The findings gained in this chapter were further used to design a unique pedestrian bridge formed by the curved in plan flat arch, where to transfer of the large bending moments a steel pipe was designed. Several variants with different span and rise of the arch in plan were tested. From the tested variants was then selected footbridge with a span of 45 m and with the rise of the arch 10 m, which seemed to be the best solution according to the calculations and it was further analyzed in detail. The studied structure is formed by curved concrete slab that is stiffened through the steel brackets on the inner side of a steel tube with a graded thickness. The external cables that are situated in the handrail pipe balance the dead load torsional moment. Designed structure and the static analysis procedure were verified on a fully functional 1:6 scale model. The thesis describes the model analogy used for the design of the model, its structural design and its implementation. Load tests on the model confirmed correctness of the design of the proposed curved in plan pedestrian bridge, its high carrying capacity and the accuracy of the developed procedure of static analysis. Results and experiences acquired from the design and the realization of model are the basis for a practical realization of studied structures. The last part of the thesis deals with the possibility of replacement of the steel components with concrete in pedestrian bridges formed

The PhD thesis deals with the possibility of performing dynamic tensile tests. For this purpose, Split Hopkinson Pressure Bar Test (hereinafter SHPBT) is used. The basic construction of SHPBT device is designed to perform dynamic compression tests on materials (metals, plastics, and ceramics). The obtained results are deformation stress – strain and strain rate – strain dependences. SHPBT is capable of testing materials at high strain rates up to 10^2 – 10^3 s-1. It was created a special device for dynamic tensile tests of materials at high strain rates. The created device uses the basic construction of SHPBT. The special device is used for testing flat specimens with 2 mm thickness. It was recognized by the Industrial Property Office of the Czech Republic as a utility model with number 23703. The specimens used for dynamic tensile testing were made of austenitic stainless steel (WNr. 1.4301) with 2 mm thickness. The verification of created device was carried out by numerical simulation. The numerical simulation was performed by ANSYS LS – Dyna software.

This diploma thesis is focused on methodology for sorting of solid fired bricks for reconstruction of historical buildings. The theorethical part of this thesis includes description of production technology of solid fired bricks and diagnostic methods. In practical part there are these methods aplied on the solid fired bricks, which are intended for reconstruction of the bridge in Sedlec. There are monitored changes in structure of solid fired bricks caused by repeated freezing and defrosting. This changes are monitored by resonant frequency method and ultasonic pulse method.

In this thesis, an effect of a tyre defect on the driving dynamics of a vehicle is dealt with. The first part of the thesis is mainly concerned with the vehicle dynamics, road resistance, adhesion, orientation characteristics of the tyres and slowing down. This chapter is followed by an overview of the manufacturing process and construction of modern passenger car tyres. The practical part is focused on driving tests that are used to demonstrate the influence of tyre defects on handling characteristics of the vehicle. The main focus of this thesis is on directional variation, braking distance, deceleration and lateral acceleration. The very end of the thesis concentrates on tyre defect in higher speeds and its after-effects as well as precautions for mitigation of these after-effects.

This master´s thesis is focused on chosen dynamic parameters of a sport vehicle represented by student formula Dragon 7 and comparison of these parameters with conventional vehicles represented by two exemplars of ŠKODA Superb III. Driving tests used for the comparison are simulating the real driving situations from the roads in order to possibly use those for the road accident analysis in the future. All the measurements were taken under lower adhesion conditions which might help solving of the road accidents under such conditions in the future. There is also a description of vehicle driving systems and components which have an influence on the vehicle´s driving dynamics incorporated in the thesis.

The presented diploma thesis deals with the evaluation of the influence of the addition of 30, 60 and 90 % of recycled material on the structure and mechanical properties of high-density polyethylene (HDPE), where recycled material represents both HDPE from a several years old part and material multiple reprocessed by extrusion. The changes of supramolecular structure were examined by calorimetric measurement, which did not indicate degradation of the material due to multiple extrusion. Mechanical properties were investigated by tensile tests and dynamic-mechanical analysis. Both measurements showed the same trend, where the first and second pass of the material through the extruder led to improved mechanical properties, e.g. to increase stiffness, while the influence of the third and fourth passes through the extruder had not a significant effect on the mechanical properties. In terms of the structure and mechanical properties, a positive effect of the combination of material after the second extrusion passing (30%) with virgin material was recorded.

The subject of this thesis is the analysis of the negative effects associated with the operation of a trailer for a personal vehicle with respect to the design speed, technical checks and analysis related legislation. Its work is drawn from the measurement, cooperation with leading Czech production plant trailers Vezeko s.r.o., an organization engaged in the implementation of engineering controls DEKRA Automobil a.s. and available literature, including electronic resources. Results of the work end with proposals for specific measures to minimize the identified adverse effects.