Simulação numérica para o crescimento de trincas em dentes de engrenagens utilizando o método estendido dos elementos finitos

Abstract

Austempered Ductile Iron (ADI) has stood out in the last decades due to its excellent mechanical properties when compared to other groups of cast iron and with some families of steel. The tensile strength, machinability, fatigue limit and wear resistance stand out as important properties. The ADI has graphite nodules in its microstructure, and these nodules act as stress concentrators in the material, but also guarantee ductility as an important property of this material. In this way, a pair of spur gears manufactured in ADI were modeled to simulate contact between the teeth of this pair. The application of the load was performed at a point defined as load radius. Subsequently, an initial crack was inserted into the model and nodules of different sizes and positions were added near the tip of the crack. The eXtended Finite Element Method (XFEM) was used as method to crack propagation, since that it is not necessary to remesh at the crack tip for each iteration. Given the simplifications used in the numerical model, the crack propagation was validated and qualitative results were generated. The results show that the size and position of the graphite nodule in relation to the crack tip are the factors that have the most influence on crack propagation.