Análise da falha prematura de eixos de tração aplicados em equipamento autônomo para alimentação de suínos

Abstract

Over time, the agribusiness segment has been increasingly modernizing and employing new technologies, both in agriculture and livestock. The adoption of modern machines and new management practices made the agribusiness sector one of the main revenues of the Brazilian GDP, making the branch important for the national economy. In this work, an investigation was carried out on the premature failure of traction axles applied to an autonomous robot for feeding pigs, through structural analysis using the finite element method, and analytical calculations. The failure of the component harms the activities carried out by the breeder, as the equipment becomes inoperative, making it necessary to carry out the work manually. To carry out the study, the loads applied to the axis were defined under the conditions: static (machine stopped), acceleration, work (uniform rectilinear movement), and braking. Furthermore, to determine the causes of early breakage, a series of laboratory tests were carried out on a part that failed in the field, these are: tensile tests, chemical composition, hardness and fracture profile. Using the FEM method, through the Ansys software, where the values of tensions and deformations were obtained. Even having acquired the values of the acting voltages through the FEM method, it was decided to calculate the voltages analytically by comparing them with the simulation values. Therefore, in both methods, the greatest effort corresponds to the region where the component breaks, which is in the keyway that transmits the torque. Fatigue calculations were carried out using the Gerber, ASME-Elliptical, Morrow and SWT criteria, using analytically calculated stress values. As the loads acting on the axle decrease as the equipment travels along the route supplying food to the animals, the life estimation method based on accumulated fatigue damage was implemented. The results show that tiny radii or even the absence of these have a direct impact on high values of stress concentration, and the conclusion of the fatigue analysis using the Gerber criterion, for acceleration and braking cycles with maximum load transported, is that the shaft has a finite life, fracturing with just over 85 thousand cycles, in the case of accumulated damage, the shaft fails with just over 496 thousand cycles. These outcomes indicate the need to reevaluate the drive shaft design, minimizing and/or eliminating stress concentrators, in addition to considering torque distribution, to ensure a longer useful life. [resumo fornecido pelo autor]