Análise de mancais de rolamento com falha localizada utilizando métodos de elementos finitos

• Ano de defesa: 2024
• Autor(a) principal: Elias de Almeida Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais
• Palavras-chave em Português: Engenharia mecânica; Análise modal; Mancais; Rolamentos; Método dos elementos finitos; Mancal de rolamento; Dinâmica vibratória; Elementos finitos
• Link de acesso: https://hdl.handle.net/1843/82324

Ball bearings are essential components for the efficient operation of machinery and equipment. However, to ensure their longevity and performance, proper maintenance is crucial, including regular lubrication, periodic inspections, and correct assembly. Early identification of wear or failure signs can prevent unplanned downtime and high repair costs. This study aims to provide a theoretical reference on bearing failures, vibrational dynamics involving these machine elements, and the influence of a localized failure on the outer race of a bearing housing through static linear analysis using finite element simulation and analytical calculations, as well as the analysis of its naturais frequencies and stress distribution. Initially, this study is based on experimental data obtained from theoretical references focused on bearing failures and a model of a Deep Groove Ball Bearing – 6205 RS, sourced from the SKF bearing manufacturer’s website, similar to the theoretical reference. The bearing features an inner race diameter of d_i=25mm, Outer race diameter d_o=52mm , Pitch diameter d_m=39,0098mm, Ball diameter D=7,94004mm, having a total of nine balls, with a contact angle of 0°, assuming a bearing speed of ω_r=1797 r/min, Sampling frequency 12hz, Load–deflection fator of 〖1.5779 〗^* (10^10.5 ) N⁄m^(3⁄2) . Next, to validate the experimental data from the theoretical reference, an analytical and numerical methodology using the finite element method (FEM) was employed, focusing on the key process parameters such as vibrations and modal analysis, given the continuous advancements in rotating machinery applications. The study was conducted for the bearing model without defects, according to the specifications mentioned above, as well as for a model with an outer race defect. The failure introduced in the outer race for the study has a cylindrical shape with the following specifications: failure diameter of 0.1778 mm and failure depth of 0.2794 mm. The frequency values of the reference model for the similar model obtained from the SKF manufacturer’s website were validated analytically using Smath Solver. The obtained values were as follows: the Ball Pass Frequency of the Outer Race (BPFO) in the theoretical model was 107.5009 Hz, whereas in the 6205-2RS bearing model, it was 109.0385 Hz, representing a 1.43% increase. This increase can be attributed to differences in material properties or contact conditions between the models. In the static linear analysis using finite element simulation, computational simulation was conducted in the Ansys finite element software to validate the model. This modeling considered deformations, von Mises stresses, contact stresses, and the frequencies of the first six vibration modes of the bearing under a rotational speed of 60 rpm for the modal analysis. The maximum calculated stress was 29.46 MPa, significantly lower than the yield limits of common steel (250 MPa) and SAE 52100 steel (360 MPa), indicating that the bearing operates within safe stress limits. In the theoretical model, the outer race failure mode occurs at amplitude 2, corresponding to the second vibration mode of the defective bearing in the Ansys simulation. The vibration analysis considered six vibration modes, as these six modes correspond to the degrees of freedom of a rigid body in three-dimensional space. Finally, the study contributed to the understanding of nonlinear vibration mechanisms in defective bearings while also validating a theoretical model through comparisons with real data and computational simulations. This highlights its importance and applicability in practical engineering scenarios.