Investigation of the stresses in helical bevel gears using finite element method

In this study, variations of the stresses that occur in teeth of different types of bevel gear systems are investigated according to geometry and working conditions. Different geometries and working conditions are obtained by changing the base helix angles, profile modification ratios, rotational speeds and intersection angles of shaft axes. Because of the geometrical complexities of bevel gear systems, it is costly to constitute a precision experimental system of these types of gears. Thus, experimental study is not an appropriate method to make a comprehensive research. However, it is possible to realize comprehensive and comparative analyses by forming a lot of different models in the computer environment when the calculations are made correctly and an appropriate analysis procedure is defined. The method to investigate the variations of the stress formations according to the geometry and working conditions in the teeth consists of four stages. In the first stage, bevel gear systems are calculated according to the input parameters and geometrical parameters are determined according to these calculations. In the second stage, gear systems are modeled in the computer environment by using the output parameters. In the following stage, three dimensional dynamic contact analyses are realized with the solid models. In the final stage, analyses results are commentated comparatively. For each parameter, functions are achieved with curve fitting method, which calculate the stress values in the solution range by using the points in which finite element analyses are realized and the stress values in these points. For these functions, local and regional extremum points are determined in the solution range with classical single variable optimization technique. According to the obtained results; helix angle, profile modification ratio, rotational speed and intersection angle of shaft axes have significant effects on maximum stresses which occur in the contacting teeth.