Monitoring the health of vibrating gears is important to ensure proper operation especially in potentially life-threatening structures, such as helicopters, nuclear power plants, and uninterruptible power supply transitions in hospitals. The most common monitoring technique is casing mounted accelerometers to measure vibration. In contrast, during the last few years acoustic monitoring techniques have also provided a few diagnostic methods for gear failure. Current diagnostic methods to indicate improper gear behavior use either existing vibration data, recorded from defective gear systems, or modern dynamic models predicting gear failure behavior. This thesis uses dynamic models to indicate, predict, and diagnose healthy and unhealthy gear systems. Influence of Tip Relief on contact forces are introduced for a decent understanding of gear dynamics followed by evaluation of common gear failure mechanisms. Two software systems were used to model gear failure: Adams®, a vibration based software that uses a rigid-elastic model for multi-body dynamics, and LSDYNA ®, a transient dynamic finite element solver, capable of solving acoustic problems with the boundary element method. Results describe tooth loads along the line of contact with respect to different Tip Reliefs and contact ratios. Gear failure is examined using a Fast Fourier Transformation to characterize patterns that can be used to diagnose unhealthy gear systems. Agreement of experimental results validates theoretical predictions of analytical and numerical solutions of gear failure especially of tooth breakage.

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.

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.

This diploma thesis primarily deals with the transmission error issue which is one of the dominant sources of vibration in gear pairs and transmission systems. The vibrations subsequently generate noise which is often subjected to increasingly stricter demands across the industry, including the automotive one. It turns out that reducing the peak-to-peak value of the transmission error has a beneficial effect on the vibro-acoustic properties of gears and gear pairs. This thesis aims to determine the transmission error under static conditions, since a gear pair with a low static transmission error is a good assumption for a low transmission error even under dynamic effects. The resulting values of the transmission error can be influenced already during the design of the gear macro-geometry. It is also suitable to apply micro-geometric adjustments – modifications to the gear teeth. For this reason, the search part of the thesis is dedicated to theoretical knowledge, especially concerning the geometry of gears, modifications of teeth and the overall transmission error and its determination. The transmission error can be determined in several ways, including a technical experiment. However, due to time and financial reasons, this is not always possible, and therefore, the possibility of using numerical simulations is offered. In this thesis, the approach using stress-strain quasi-static contact analysis using the finite element method in Ansys Workbench software is used. The advantage is, among other things, a good comparability of results. The input to the FEM analysis is 3D CAD geometry – in this case, it is specifically a helical gear pair with parallel axes. The model/assembly of this gear pair is created in PTC Creo software fully parametrically, so it is possible to generate arbitrary gear pair configurations by changing the input parameters, which significantly saves time. At the end of this diploma thesis, the stress-strain analysis of various gear configurations is evaluated, with respect to the equivalent stress and contact pressure. Furthermore, the static transmission error – its graphs and peak-to-peak values – is determined from FEM analyses for different gear geometry, including tooth modifications, and for various loading torques. Last but not least, the effects of contact/overlap ratio and centre distance are evaluated.