Inaug.-diss.--Jena. / Lebenslauf. "Literaturverzelchnis": p. 6.

Inaug.-diss.--Jena. / Lebenslauf. "Literaturverzelchnis": p. 6.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xiii, 166 p.: ill. Includes bibliographical references (p. 159-166). Available online via OhioLINK's ETD Center.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 163-170).

Orientador: Robson Pederiva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T15:55:46Z (GMT). No. of bitstreams: 1 Santos_BrunoSavioBoghossiandos_M.pdf: 1516247 bytes, checksum: 56409e552f694a7e6380abecffa30505 (MD5) Previous issue date: 2010 / Resumo: O acoplamento entre os movimentos de rotação do braço do tensionador e os movimentos transversais dos tramos de correia adjacentes à polia do tensionador é investigado neste trabalho. As equações de movimento de um sistema composto por três polias, correia serpentina e um autotensionador são derivadas a partir do Princípio de Hamilton. Estas equações formam a base para as análises do equilíbrio e vibração linear. Dois métodos são descritos para a solução das equações do equilíbrio. A solução numérica converte rapidamente e fornece a base para a análise da vibração linear. A solução linear aproximada fornece uma indicação da efetividade do design do tensionador, ou seja, sua capacidade de manter a tensão de tração constante, medida a partir da constante de suporte desenvolvida nesta análise. Uma solução de forma fechada baseada no método de Holzer é proposta para analisar as vibrações livres. Dois loops de iteração são utilizados na solução. Um loop interno para a estrutura cíclica e um loop externo para o tensionador. A principal conclusão deste estudo é que um acoplamento linear existe entre os movimentos de rotação do braço do tensionador e os movimentos transversais dos tramos de correia adjacentes à polia do tensionador e produzem respostas dinâmicas diferentes de quando o mesmo é desconsiderado. Um aplicativo para a implementação do modelo foi desenvolvido em Visual Basic / Abstract: The coupling between the tensioner rotational movement and the transverse movement of the belt spans adjacent to the tensioner pulley is investigated in this study. Hamilton's Principle is used to derive the governing equations of motion which provide the basis for the equilibrium and linear vibration analysis. Two methods are described for solving the equations of equilibrium. The exact, nonlinear, iterative solution converges quickly, and provides the basis for the linear vibration analysis. The approximated solution provides an indication of the system design effectiveness by the tensioner support constant derived in the study. A closed form solution based on the Holzer's method is proposed for solving the linear vibration analysis problem. Two iterations loops are used in the solution. An internal loop for the cyclic structure and an external loop for the tensioner arm. A major conclusion of this study is that linear coupling exists between rotational and transverse vibrations, and often produces different dynamic response than that predicted by ignoring coupling. A software was developed in Visual Basic to implement the model / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

No description available.

Orientador: Robson Pederiva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-14T00:38:10Z (GMT). No. of bitstreams: 1 Garcia_Ubirajara_M.pdf: 2857015 bytes, checksum: 43af4c00365bf303c80b6b5d1be9e9be (MD5) Previous issue date: 2009 / Resumo: Neste trabalho desenvolve-se um método, que permite avaliações de parâmetros, para o estudo do projeto de um sistema auto-tensionador no controle de suas vibrações transversais e forças atuantes. Parâmetros construtivos e operacionais, como: a geometria, inércia, rigidez da mola do auto-tensionador, rigidez da correia e condições de operação, como: frequências de excitação, forças estáticas e dinâmicas são obtidas em um sistema auto-tensionador de transmissão por correias, aplicados em automóveis de passeio comerciais. Com a modelagem dinâmica de um grau de liberdade, calcula-se a força de atrito e fator de amortecimento, que estabelece o controle de vibrações e forças atuantes no sistema. Os resultados das simulações computacionais são analisados e comparados com os resultados obtidos pelo protótipo experimental desenvolvido. Os resultados tecno-experimentais indicam ajuste satisfatório, o que representa uma contribuição significativa, para o estudo de sistemas auto-tensionadores e na melhoria do controle de vibrações e forças atuantes em correias dentadas, em tempo real de projeto. / Abstract: This investigation describes a method, which permits evaluating the best parameters, in the study of tensioner project system in its transversal vibration control and actuating forces. The construtive and operating parameters, as: geometry, inertia, tensioner spring stiffness, belt stiffness, and operating conditions as: excitation frequencies, estatic and dinamic forces are obtained in a tensioner of transmition by belts with market vehicles aplication. With a dinamical modelling of one degree of fredow are calculated the atrict force and damping factor that establish the vibration control and system actuating forces. The computational simulating results are analysed and compared with obtained results from the developed experimental prototype. The tecno-experimental results have a satisfactory adjust, that represents a significative contribution, for tensioners systems study and the better control of vibrations and actuating forces on driven belts, in project real time. / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis presents a comprehensive study of the effects of material, geometric and operational parameters on flat belt-drives steady-state belt stresses, belt slip, and belt-drive efficiency. The belt stresses include: belt rubber shear, normal, axial and lateral stresses; reinforcements tension force; and tangential and normal belt-pulley contact stresses. Belt slip is measured using the driven over driver pulleys’ angular velocity ratio. Each parameter was varied over a range to understand its impact on the steady-state belt-drive response. The material parameters studied are belt axial stiffness and damping, belt bending stiffness and damping, and belt-pulley friction coefficient. The geometric parameters studied are pulley center distance, pulleys diameter ratio, and belt thickness. The operational parameters studied are the driver pulley angular velocity and the driven pulley opposing torque (load). A high-fidelity flexible multibody dynamics parametric model of a two-pulley belt-drive system was created using a commercial multibody dynamics code. In the model the belt’s rubber matrix is represented using three-dimensional brick elements and the belt’s reinforcements are represented using one dimensional beam elements at the top surface of the belt. An asperity-based Coulomb friction model is used for the friction forces between the pulley and belt. The pulleys are modeled as rigid bodies with a cylindrical contact surface. The equations of motion are integrated using an explicit solution procedure. Unlike prior models which use one-dimensional truss or beam elements for the belt, the present model uses a three-dimensional belt model which introduces the effect of the thickness of the belt rubber matrix (modeled using brick elements). This enables a more accurate prediction of the belt stresses and slip than prior models. This thesis resolves in more details the complex stick-slip friction behavior of an axially flexible belt coupled with the shear effects of a flexible rubber cushion and at the same time shows the effect of the main system parameters on this stick-slip behavior. Some of the important conclusions of the thesis include: (1) the driver pulley has two distinct contact zones - a negative traction zone and a positive traction zone - while only one traction zone is present over the driven pulley; (2) the width of the negative traction zone on the driver pulley increases with the belt-pulley coefficient of friction and decreases with the belt axial stiffness; (3) the maximum belt tension and normal contact stress occur on the driver pulley and increase with the belt thickness, belt axial stiffness, and coefficient of friction; (4) belt-drive energy efficiency increases with the belt axial stiffness, and decreases with belt thickness, belt bending damping, belt operating speed, and operating torque load. The belt-drive modeling methodology presented in this thesis which enables accurate prediction of the belt stresses and slip can in turn be used to more accurately predict the fatigue life, wear life, and energy efficiency of belt-drives.