National Repository of Grey Literature 319 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Tractor cabin skelet optimization
Saňák, Stanislav ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis addresses the issue associated with the design of the tractor cabin frame. Agricultural machinery, including tractors, is utilized for work in highly challenging conditions such as fields or forest terrains, characterized by uneven, hilly, and often unpaved surfaces. Working in such extremely hazardous environments poses a significant challenge, especially for the operators of these machines. It is very common for drivers to lose control of the vehicle while navigating such terrain, resulting in the tractor tipping over on its side or roof, and in worse cases, experiencing repeated rollovers due to inertia. In such situations, the presence of a protective frame around the tractor cabin is the only possible means of crew rescue. However, the rollover of such a vehicle imposes extreme stress on the cabin frame due to the weight of the tractor and often its cargo. Historically, rollovers have been the leading cause of accidents resulting in fatalities of tractor crews, which prompted the establishment of standards aimed at reducing this type of accident. Tractors are tested against these critical situations to ensure the maximum possible crew safety. Nowadays, every manufactured tractor must comply with these tests. Since these tests are of a destructive nature, it is more cost-effective and time-efficient to first conduct tests using numerical simulations, within which the tractor cabin is optimized to successfully pass the given tests. The actual test is then performed on the final, already optimized cabin frame. In this study, a numerical simulation using the finite element method was conducted on the tractor cabin skeleton for the ROPS (Roll-Over Protective Structure) test, which simulates the tractor overturning. Based on the simulation results, optimizations were made to the cabin that were necessary to pass this test, which consists of several load cases. The optimized cabin frame was subsequently subjected to a basic dynamic analysis (modal analysis). This analysis identified the natural frequencies of the cabin that could be excited in the event of typical excitations acting on this structure (road surface irregularities, vibrations from the engine unit, and so on). Finally, based on real values obtained from experimental measurements, a harmonic analysis was performed. This analysis monitored the response of the frame to excitations corresponding to actual excitations from the engine unit.
Development of velomobile
Adámek, Silvestr ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The bachelor thesis deal with one of a lesser-known means of transport as velomobile certainly is at the moment. This research aims to the development and overall complexity of these modern human-powered vehicles using aerodynamics to its advantage. Due to absence of internal combustion engine, velomobiles reduce negative environmental impacts but also dependence of fossil fuels. Different specifications of velomobiles such as wheels configuration, propulsion system and its usage are being analysed in this study as well as main construction elements or invariably innovated materials. For instance, carbon fibres are one of the modern materials contributing to the strength and lightness of velomobile. Modern approaches goes hand in hand with the development of these modern vehicles, aerodynamics optimalizations of the vehicle body, construction strength or questions regarding electric propulsion to be more specific. Although velomobiles represent an efficient way of transportation, initial costs, weight and size could be impediment to the wider public.
Numerical simulation of gear mesh stiffness
Rackovský, Daniel Milan ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The diploma thesis deals with the simulation of the spur gears mesh stiffness. The introductory part of the thesis presents a detailed review of the knowledge in the field of gear theory, gear error and also NVH of gears. The next part of the thesis describes the basic principles of the function of the parametric FEM model of gear mesh, which was developed for the purpose of this thesis. The last part of the thesis presents the results of FEM simulations in which the effect of manufacturing error of the gears on the STE waveform was investigated. The basis of the simplified production error model was the sine function. The effect of the number of periods of this function and the magnitude of the amplitude on the STE waveform was investigated. The effect of the magnitude of the load torque on the STE of the production-error gear was also verified. The magnitude of the amplitudes of the sine function was determined to match the allowable wheel shape tolerances according to ISO 1328-1. The problem was solved in Ansys Mechanical APDL using a parametric FEM model based on APDL language.
Gear coupling modification
Mahel, Pavel ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis deals with the design of a gear coupling. The main intention is to design the optimal shape of the clutch gearing for the given operating conditions. Due to the special barrel shape of the teeth on the external gearing, these couplings enable the torque to be efficiently transmitted even in the case of misalignment of the connected shafts. In the case of an improperly designed coupling, a number of problems can occur that could affect the life of the coupling. These problems include in particular the generation of excessive vibrations and noise. It is necessary to choose the right lubrication system for long-term coupling life. To eliminate problems with gear couplings, it is necessary to ensure a suitable distribution of contact pressure at a given degree of misalignment. The introductory part of the thesis contains a comprehensive view of the issue of gear couplings. The next part deals with the structural design of the whole gear coupling and the improvement of the existing model. The following is a description and analysis of two different computational models of gearing that allow for different maximum degree of misalignment. The difference between the two gearing models is in the different geometry of the tooth shape on the hub. In the computational analysis, the most important monitored parameter was the course of contact pressure on individual teeth at a given degree of misalignment. From the performed computational analyses, result files are processed that compare the contact pressure and the number of teeth in engagement for different degrees of misalignment. The above analyses were performed using the finite element method in the calculation program Ansys Workbench.
Planetary Gearboxes in Passenger Cars Construction
Timko, Richard ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
The bachelor's thesis focuses on the research collection of planetary transmissions used in passenger cars, based on their conceptual arrangement and drive type. A simple planetary gear set and the Ravigneaux with the Simpson compound planetary gear trains are kinematically described, aiming to establish their basic kinematic equations. Subsequently, specific examples of planetary gearboxes are selected and described for internal combustion engine, electric, and hybrid drives. Additionally, a complete kinematic and force analysis of the ZF 8HP automatic transmission is conducted.
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.
Reduction of vibration and noise at passenger car interior
Patočka, Pavel ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis addresses the issue of reducing vibrations and noise in the interiors of passenger vehicles, which is commonly tackled today by additional soundproofing using vibration-damping and sound-absorbing materials. In the research part of this thesis, besides methods for measuring vibrations and noise, the properties and application methods of these materials are described in detail. As the name of these materials suggests, their main goal is to dampen vibrations and absorb sound. Their principle, in simple terms, consists of converting mechanical or sound energy into another form of energy (most commonly thermal energy). However, the application of these materials to a structure affects its modal properties, including natural frequencies and mode shapes. To further investigate the influence on natural frequencies and mode shapes after applying vibration-damping material to a structure, both numerical and experimental modal and harmonic analyses of a simple metal sheet sample were conducted. The benefits of vibration-damping and sound-absorbing materials in terms of additional vehicle soundproofing were evaluated based on a road test conducted under real operating conditions.
Autonomous Tractors
Kučera, Jan ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This thesis discusses autonomous tractors, describing the difference between standart tractors and autonomous tractors, which are then discussed in further detail. It describes the steering and control options for autonomous tractors, electronic control and agregation control options.
Optimizing a highly loaded components for motorsport
Šišpera, Petr ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis deals with optimizing the rear suspension of the fifth generation Honda Civic for motorsport application. The goal is to reduce weight while increasing stiffness and precision in wheel control. The work is based on the properties of serial components, which are analyzed using FEM analysis in the Ansys program. Load conditions are calculated from vehicle dynamics and the loading of individual arms from the suspension kinematics. Suspension components are first modeled and analyzed and this data provides input information for optimization. Individual components are initially topologically optimized, based on which models are created for deformation stress analysis. The properties of the serial parts are ultimately compared to optimized ones under the most critical loading conditions and the result of the work is an optimized suspension system with lower weight and higher stiffness.
Computational Modelling of the Automotive Gearbox Dynamics Using Multi-Body Approach
Suchý, Pavel ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
The thesis deals with construction of a computational model of the manual automotive gearbox MQ281 in MSC ADAMS View software, on which several static and dynamic operating states of the gearbox are simulated. The input for the MBS model construction is the CAD assembly of the gearbox in necessary detail and parameters of all gears. The computational model uses a custom model of bearings and the engagement helical spur gears based on the transmission error. The outputs of the simulations are courses of forces and moments acting in bearings, gears and synchronizing clutches, courses of shafts deflection, courses of angular velocities of shafts and gears, frequency analysis of operating states.

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