Richards, Evan Ernest,
Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
Psychologists have found that noise reduces human efficiency. This effect may be considerable even for the most phlegmatic individuals. Moreover, almost everyone objects to unnecessary noises. In recent years there has arisen a very insistent demand for quieter electrical apparatus. This applies particularly to household apparatus such as refrigerator motors, vacuum sweepers and the like. Practically noiseless motors are also required for various drives ( refrigerating plants, circulation pumps of hot water systems, big ventilating systems for rooms, organ bellows etc. ) in non industrial plants such as storerooms, business houses, hotels, hospitals, churches, theatres etc> where all noise should be suppressed. It must also be noted that the stage has been reached where it is taken for granted that the products of the better known manufacturers will give entirely satisfactory performance, and often, the deciding factor between various makes is only the quietness with which the equipment operates. However,noise and vibration are not merely annoyances which may affect the sale of a product or lower the efficiency of a worker. They are often evidences of defects in design and manufacture which seriously affect the life of the equipment and, in many cases, the safety of the user.[...]
No description available.
Theoretical and experimental investigations on radial electromagnetic forces in relation to vibration problems of induction machinesBalan, Anil 01 January 1997 (has links)
Accurate assessment of the electromagnetic excitation forces and the vibration behaviour of stators is essential to arrive at a suitable design for quiet operation of an electrical machine. These electromagnetic forces are produced on the surfaces of the stator and rotor along the air-gap periphery. The physical mechanisms underlying the production of the electromagnetic forces, and the characteristics of the ensuing vibrations are described in this thesis. <p>In this thesis, comprehensive analytical methods are developed for the determination of the radial electromagnetic forces in squirrel-cage and wound-rotor induction machines. Various magnetic fields are generated due to the distribution of the windings in slots, the slotting of the stator and rotor surfaces, and the magnetic saturation of the iron. The air-gap fields are determined using the permeance method by expressing the MMF and the air-gap permeance as waves. <p>In the analyses, the mutual interactions between the stator and rotor are incorporated. Asthe load increases, these interactions become prominent and influence significantly the nature of the air-gap field. Their effects on the electromagnetic forces are discussed from the perspective of the production of vibrations. Extensive investigations were conducted on a 7.5 kW squirrel-cage induction motor and a 70 kW wound-rotor induction motor to verify the validity of the analyses. The comparisons made between the experimental and the analytical results prove the general validity of the analytical methods. <p>Conclusions are drawn with a view to determine the actual role played by the harmonic air-gap fields on the production of the electromagnetic forces and the ensuing vibrations. In the course of these investigations, an experimental set-up which is particularly suited for the measurement of magnetic fields, magnetic forces, resonant frequencies, vibrations and noise was developed. A fundamental study on the vibration behaviour of electrical machine stators using an experimental modal-analysis is presented in the thesis. Modal-analysis is a process of forcing a structure to vibrate predominantly at a selected resonance. In order to achieve this, distributed electromagnetic forces are used.<p>Detailed investigations were conducted on the stator models of a 120 hp induction motor to study their vibration behaviour, and to critically examine the damping present in them. The physical interpretations of the results given in the thesis would help in acquiring a better understanding of the vibration behaviour of stators in relation to the problem of electromagnetic acoustic noise in electrical machines. This work was supported by the National Sciences and Engineering Research Council of Canada through grant no. OGP0004324.
Influência das forças de inércia e do balanceador de massas na dinâmica do motor de combustão interna / Influence of inertia forces and mass balancer on internal combustion engine dynamicsSelim, André Baroni 16 August 2018 (has links)
Orientador: Airton Nabarrete / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T19:07:22Z (GMT). No. of bitstreams: 1 Selim_AndreBaroni_M.pdf: 8247651 bytes, checksum: 306a914d67d3207fb1d8f193b3bf7bd2 (MD5) Previous issue date: 2010 / Resumo: Este trabalho visa estudar a influência do balanceador de massas e das forças de inércia dos componentes internos móveis do motor na dinâmica do motor de combustão interna apoiado sobre amortecedores de vibrações. Para o estudo da influência do balanceador de massas, diversas análises experimentais foram realizadas com um motor em dinamômetro. Chegam-se nas conclusões através da comparação dos deslocamentos medidos do motor com e sem balanceador de massas. Para que a influência das forças de inércia dos componentes internos móveis do motor fosse estudada, um modelo matemático foi criado. Neste modelo consideram-se as forças vindas dos componentes internos móveis atuando em um corpo rígido, neste caso o bloco do motor, apoiado sobre quatro amortecedores de vibrações com seis graus de liberdade. Variam-se dados construtivos como massas e geometria dos componentes internos móveis do motor observando a sua influência sobre o comportamento dinâmico do motor de combustão interna. A validação deste modelo matemático ocorre por meio da comparação de seus resultados com os resultados reais observados nas análises experimentais / Abstract: This work aims at studying the influence of mass balancer and inertia forces coming from engine internal components on internal combustion engine dynamics supported by vibration dampers. For mass balancer study several experimental analyses were performed with a dynamometer. The conclusions are obtained by comparison between measured engine displacements with and without mass balancer. To study the influence of inertia forces from engine internal components, a mathematical model was developed. In this model the inertia forces act on a rigid body, the engine crankcase, supported by four vibration dampers and with six degrees of freedom. Some modifications are made on engine internal components such as mass and geometry observing what is their influence on internal combustion engine dynamics. The mathematical model is validated by comparison against experimental analyses / Mestrado / Dinâmica / Mestre em Engenharia Automobilistica
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