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Noise Reduction Methods in Transmissions
Benda, Matouš ; Zubík, Martin (referee) ; Prokop, Aleš (advisor)
Transmissions are basic elements of cars, which are important parts of everyday life. Expect targeted properties transmissions have a great influence for a total noise emitted by car. This thesis deals with possibilities of reducing this noise. In a first part of this thesis, reader is acquainted with the basic knowledge of acoustics, where are definitions of sound and mentioned noise. Another part analyzes transmission, as a mechanical component formed by smaller machinery units. This description is important for understanding transmission of vibrations in the structure, which further due to vibrate surroundings, which the human ear perceives as noise. These vibrations are mainly generated between meshing gears, and therefore the transmission error, which is responsible for these vibrations is analyzed in the next section. The last part discusses noise reduction methods, partitioned by the transmission components, in which are these methods applied.
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Design of a test rig for the development of gears for passenger car applications
Běloušek, Ondřej ; Řehák, Kamil (referee) ; Czakó, Alexander (advisor)
This thesis is aimed to design of test rig which serves for measuring of vibro-acoustic characteristics of gears used in automotive gearboxes. In the theoretical part, the basic principles of initiated vibrations caused by gear meshing are described, especially due to transmission error as an important parameter. Next part of the paper is dedicated to description of experimental approach used in measuring of this characteristic and evaluation of used conceptual designs is also included. Own designed closed loop test rig allows to measure static transmission error of various sizes of gears even if the shafts are not parallel under the specific operating range. The main part of the design is measuring bench, whose developmental phases are shown, and which carries all important components for the measurement. Thesis also includes modal analysis of those constructions performed in ANSYS Workbench. The main parts of closed loop are described in details and static structural analysis of torsional loading device is done. Final part of the thesis compares analytical versus numerical approach to calculate safety factor of the critical point of a chosen shaft.
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Transmission error in spur gears
Bartošová, Daniela ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This master’s thesis is deal with the area of determining the static transmission error in spur gears. Nowadays, around vibration and noise formation, the issue of transmission error is being discussed quite often. In the first part of this master’s thesis, there is a description of the theoretical requirements concerning the above stated issue. These theoretical requirements are further applied in parametric planning of the spur gears as well as in measuring the transmission error itself. In this master’s thesis, both the detailed description of planning the parametric model of spur gears and the strain-stress analysis may be found. These requirements are needed for calculating the transmission error. In conclusion of this master’s thesis, specific results of the static transmission error in spur gears achieved at diversifying load torque, center distance modifications as well as tip relief modifications of spur gears are being presented. The issue was solved by computation approach with the help of CAD software called Creo Parametric and FEM software called Ansys Workbench and Ansys Mechanical APDL.
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Computational Modeling of Gear Mesh Engagement Dynamics by MBS Approach
Pykal, Vojtěch ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This master’s thesis is focused on the compilation of a computational modelling of gear mesh engagement dynamics of a spur gear by MBS approach. The user input is the specific geometry of gears, the operating speed, and the load torque. The output are the forces in the gear engagement and the reaction of the forces in the wheel bearings depending on the change in the stiffness of the gear due to the changing number of teeth in the engagement and the change in the axial distance. This model is characterized by a fast and relatively accurate calculation in the time domain. This means that it can react to changes in parameters during simulation such as axial distance, speed, and torque.
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Multi-Body Computational Modeling of Transmission Dynamics
Líčeník, Adam ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This diploma thesis is focused on compiling a computational model of the transmission of a Zetor Forterra HSX tractor in the Multibody software MSC ADAMS environment. It analyses the issue of creating gears in terms of vibration and noise. The thesis describes the creation of computational model which is used for simulation of the load conditions during tractor operation. The methodology is applied to a single-stage gearbox in which is verified. Then it is used on a model of a real tractor gearbox. The response of the input load conditions is projected during the forces in the engagement of the gears which are transmitted to the bearings.
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Determination of transmission error at bevel gear
Fraňová, Zuzana ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This master’s thesis deals with the determination of the transmission error in spiral bevel gears and its minimization using tooth profile modification in order to reduce vibrations and noise of transmission systems. Gears are the primary source of vibrations transmitted through the shaft and bearings to the gearbox housing and adjacent surfaces that emit noise into the surrounding space. In order to increase the level of comfort and due to the legislative requirements, increasing emphasis is being placed on reducing the noise and vibrations of machine components, including transmission systems. This leads to the need to identify noise sources and evaluate them in terms of expected acoustic performance. The quality of the gear meshing can be judged by transmission error that is closely related to the noise and vibrations. To evaluate the quality of gears based on transmission error, experimental measurements are used that are costly and require quality equipment. Therefore, it is efficient to determine the expected transmission error already at the design stage using numerical methods. In this work a parametric model of bevel gear geometry and a numerical model for the simulation of gear meshing using FEM software Ansys Mechanical are created in order to determine the transmission error. Based on the transmission error, various load cases and gear modifications designed for transmission error reduction are compared.
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Influence of bevel gear modifications on the transmission error
Martinka, Tomáš ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This diploma thesis deals with the problem of transmission error in gears with a specific focus on bevel gears with straight teeth. The course of the transmission error and especially its peak value (PPTE) directly affects the noise of the transmissions and thus the noise of the entire gear device. In the long term, therefore, one of the main goals in the field of gear manufacturing and application is to reduce the value of PPTE. In this work, the influence of the modification of a specific bevel gear on the resulting static transmission error (STE) under static conditions is investigated. One way to modify a gear is to use a macrogeometric approach, where it is possible to adjust the number of teeth, gear modulus, gear engagement angle, and other factors that further affect the size of the gear and can significantly affect the resulting forces in the gearing. which can further lead to the impossibility of installation in the existing equipment and therefore this approach must be taken into account when designing the equipment. Another possibility is a microgeometric approach, which, with sufficient load-bearing capacity of the equipment components, will allow the assembly of gears in existing equipment while maintaining the original dimensions of the gears. The research of this thesis includes the definition and classification of gears based on the relative angle of the axes of rotation of the wheel and pinion, the geometry of the teeth and the pitch and the shape of the control curve of the teeth. Another area of focus of the research is the definition of the transmission error and the effects of its course on the noise of equipment equipped with transmissions. The practical part of this work is focused on the comparison of the course of the STE detected by the finite element method (FEM) in the program Ansys Workbench 2022/R2, into which individual variants of the gear models with applied adjustments were exported in the STEP format. and further modified in the Space Program Claim. The work is focused on investigating the effect of the size of a short height modification for multiple load moments, the effect of tooth height modification, the effect of shape modification and the effect of wheel axial position deviation on STE. The results of the analysis of the individual variants are compared based on the course of the results of the transmission errors with regard to the maximum contact stress of the flanks of the engaging teeth and the maximum stress in the heel of the tooth.
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Computational Modelling of the Transmission Dynamic Behaviour
Švub, Pavel ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This thesis focuses on constructing a computational model of a gearbox using Matlab software, with the main objective of analysing the dynamic loads that occur during gearbox operation. The thesis examines the most important sources of dynamic forces in gear mechanisms, such as gear backlash, gear mesh stiffness, bearing stiffness, and shaft stiffness. Furthermore, it provides an overview of basic mathematical models used for modelling the dynamics of gear transmissions. Based on these findings, a custom model of a two-shaft gearbox is developed, which also allow gear shifting. Synchronization with a flexibly limited force is utilized for gear shifting. This model is then subjected to various loading conditions to monitor the response of individual components, including gear forces, bearing loads, and the magnitude of transmission error.
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Design of a test rig for the development of gears for passenger car applications
Běloušek, Ondřej ; Řehák, Kamil (referee) ; Czakó, Alexander (advisor)
This thesis is aimed to design of test rig which serves for measuring of vibro-acoustic characteristics of gears used in automotive gearboxes. In the theoretical part, the basic principles of initiated vibrations caused by gear meshing are described, especially due to transmission error as an important parameter. Next part of the paper is dedicated to description of experimental approach used in measuring of this characteristic and evaluation of used conceptual designs is also included. Own designed closed loop test rig allows to measure static transmission error of various sizes of gears even if the shafts are not parallel under the specific operating range. The main part of the design is measuring bench, whose developmental phases are shown, and which carries all important components for the measurement. Thesis also includes modal analysis of those constructions performed in ANSYS Workbench. The main parts of closed loop are described in details and static structural analysis of torsional loading device is done. Final part of the thesis compares analytical versus numerical approach to calculate safety factor of the critical point of a chosen shaft.
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Multi-Body Computational Modeling of Transmission Dynamics
Líčeník, Adam ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This diploma thesis is focused on compiling a computational model of the transmission of a Zetor Forterra HSX tractor in the Multibody software MSC ADAMS environment. It analyses the issue of creating gears in terms of vibration and noise. The thesis describes the creation of computational model which is used for simulation of the load conditions during tractor operation. The methodology is applied to a single-stage gearbox in which is verified. Then it is used on a model of a real tractor gearbox. The response of the input load conditions is projected during the forces in the engagement of the gears which are transmitted to the bearings.
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