Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xx, 272 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 207-208).

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Orientadores: Katia Lucchesi Cavalca Dedini, Gregory Bregion Daniel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-25T08:34:31Z (GMT). No. of bitstreams: 1 Carneiro_AntonioCarlosSanchesGrijotaPiragibe_M.pdf: 5320137 bytes, checksum: 6c4d8edd95179d0d202cdd190a3b7792 (MD5) Previous issue date: 2014 / Resumo: O presente trabalho tem como objetivo a análise dinâmica de sistemas rotativos sujeitos a diferentes tipos de elementos instabilizadores. Os elementos abordados neste estudo são os mancais lubrificados, os selos de fluxo mecânicos e o amortecimento interno do eixo, cujas interações dinâmicas, em condições operacionais pode conduzir o sistema à instabilidade. Os mancais segmentados foram também incluídos no estudo, cujo comportamento é considerado inerentemente estável. O eixo foi modelado por meio do método dos elementos finitos, pela sua robustez, facilidade de implementação e resolução das equações envolvidas. Desse modo, os elementos instabilizadores analisados foram modelados de forma a permitirem sua adição no modelo do eixo, por meio de coeficientes dinâmicos equivalentes. Os mancais segmentados permitem duas modelagens para os seus coeficientes: a reduzida e a completa, com a última exibindo explicitamente os graus de liberdade do segmento, sendo necessárias modificações no modelo de elementos finitos para adiciona-los. A avaliação do limiar de estabilidade foi realizada por meio do método do decremento logarítmico, obtido através da solução do problema de autovalor da equação de movimento do rotor. Analisaram-se, separadamente, os efeitos da adição de diferentes mancais, selos e níveis de amortecimento interno, para visualizar a influência de cada componente na dinâmica de um mesmo eixo. As análises envolvendo o mancal segmentado incluíram ambos os modelos de coeficientes (reduzido e completo). Em seguida, foram combinados, em um mesmo eixo, diferentes tipos de mancais, selos e amortecimentos internos, em diversas análises para determinar as interações existentes entre os componentes envolvidos. A partir destes resultados, procurou-se, em todas as análises, observar os efeitos na rigidez do sistema, no nível de amortecimento e a variação do limiar de estabilidade / Abstract: The work¿s goal is to analyze the dynamics of rotating systems, considering different kinds of instabilizing elements or factors. The factors accounted in this thesis are the hydrodynamic bearings, flow seals, and internal damping of the shaft, whose dynamic interactions occurring during the system¿s operation may cause instable behavior. Besides, the tilting-pad journal bearing were studied, which behavior is considered to be inherently stable. The shaft was modeled through the finite element method, due to its robustness, ease to implement and solution of the involved equations. Hence, the instabilizing elements were modeled in order to allow their addition in the shaft¿s model, through equivalent dynamic coefficients. The tilting-pad journal bearings allow two different coefficient models: reduced and full, with the last one explicitly exhibiting the degrees of freedom of the pads, being necessary modifications to the finite elements model to contain them. The evaluation of the stability threshold was performed through the logarithmic decrement method, obtained from the solution of the eigenvalue problem of the equation of motion of the system. The effects of the addition of different bearings, seals and levels of internal damping were analyzed separately in order to visualize the influence of each component on the dynamic of the same shaft. The models with tilting-pad bearing were analyzed twice, with each one considering a different coefficients model (reduced and full). Finally, different kinds of bearings, seals and internal damping were combined in the same shaft, allowing the definition of the interactions between the involved components. From this work, the effects in the system¿s stiffness, damping level and changes in the stability threshold were observed in all analyses / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

M.Ing. (Electrical & Electronic Engineering) / Please refer to full text to view abstract

The diploma thesis deals with the issue of bearings noisiness. The bearings noisiness appears as a negative phenomenon in all the mechanical devices that generate any kind of movement. Analysis of this phenomenon enables to analyse the technical condition of the bearing and predict its defects as well. The theoretical part of the thesis is devoted to the vibration diagnostics and noisiness diagnostics, which are deeply linked. The practical part of the thesis deals with the real problem of the bearing’s noisiness in the engineering company. The main asset of this thesis is a design and successful implementation of the measures, which reduce noisiness of the selected type of the bearing.

MARTINOVSKÝ Peter: Identification and elimination of errors in the productions of bearings Diploma thesis elaborated in frame of engineering studies branch by means of identifying and eliminating errors in the production process of the clutch bearings using FMEA and Poka – Yoke. With the contribution of these methods are identified and eliminated the five most serious errors, which value of RPN exceeded a limits demanded by customers.

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