Análise da relação entre tensões e variações geométricas em engrenagens cilíndricas de dentes retos utilizando método analítico e numérico

Abstract

New materials have been used on the manufacturing of spur gears with the objective of reduce the pitting. The results achieved were satisfactory to this failure mode. However, to the other failure mode knew as bending, the stress levels obtained were high, due the mechanical properties of these materials. This job show a study of how the bending stress of the gears is changed according geometry variations are applied on its teeth. The variations imposed are related with standard geometry features of the gears, how module, teeth number and pressure angle. The gears are tridimensional modeled on Solidworks®, applying features that accelerate the creation of several parts. To make the models similar to the gears really manufactured, it is presented theoretical concepts related the building of curves which the gear teeth profile has. They are essential geometric parameters on the study of bending stress. Some analysis developed by analytical methods based in specific standard to gear sizing are used to approve a numerical model. Analytical methods almost always impose simplifications in the building of their models, so it’s common that the entire phenomenon involved on the analysis are not considerate. So, to improve the results, numerical analysis by the finite element method are developed with the commercial pack ABAQUS®. It had showed the all process developed to during the study until the numeric method validation. In each step there is a discussion about the difficulties found and the improvements deployed to both methods analytical and numerical. In the end, the generated results indicating an exponential decay of the bending stress with the increasing of the module, teeth number and pressure angle. Therewith, it is possible to evaluate which is the best geometry configuration for spur gears, which can be specified, to avoid excessive strain of bending stress.