Análise da influência de parâmetros geométricos nas tensões de flexão de engrenagens cilíndricas de dentes retos

Abstract

The use of spur gears is important to machine systems where torque transmission or power transmission between shafts it is needed. It is important to realize an effective project, because the application of load between a pair of gears can cause high wear on teeth, like pitting and even the breaking of teeth. This makes that it is necessary to change the pair. The two failures modes most common are frature in the root region by bending stress and surface fatigue by contact stress. To reduce these failures, the change of the material or geometric variations can be done, and the last one is the goal of this paper. The gears are modeled using the software Solidworks, making use of features to accelerate the creation of several models with geometric variations. To make the models similar to the gears really manufactured, it is presented theoretical concepts related to the building of curves, which the gear profile has. An analytical method was constructed based on equations presented by AGMA Standard and the bending stress equation purposed by Lewis. The final equation used to perform the resulting bending stresses on the rooth tooth refers to a modified Lewis equation, which was made to improve the results. The numerical analysis are developed using the ABAQUS commercial pack and subsequent validation with the analytical model. The main improvements made on ABAQUS are showed and discussed. In the end, the generated results shown a decay of the bending stress with the increasing of teeth number, module and pressure angle. It is also shown that the gears has the same bending stress behavior on the rooth teeth. Therewith, it is possible to evaluate what geometry configuration is the best to spur gears, to avoid excessive bending stress according to the geometric variations.