Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 216-235).

In this paper, the slipping friction is considered in the problem of a progressive wave of real fluids propagating over a permeable bottom. In the interface of soil and fluid, the ¡§no-slip¡¨ condition is relaxed and a sliding friction coefficient is introduced. Thus, the slipping effect and the permeability of bottom on the velocity near the seabed can be studied. The results indicate that the joint effect of slipping friction and permeability is crucial. The overshooting phenomena also can be explained by this joint effect.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Leamy, Michael; Committee Member: Costello, Mark; Committee Member: Ferri, Aldo. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2007. / Jeffrey Streator, Committee Member ; Richard Neu, Committee Member ; Itzhak Green, Committee Chair.

Belt drives are used in numerous applications to transmit power between various machine elements. One limitation of the use of belt drives is the poor convergence of complex models which did not make them applicable for manufacturing use in industry. A source of convergence failure is the sharp changes in the solution. It is believed that the inclusion of an Elastic/Perfectly-Plastic (EPP) friction law into the belt/pulley contact mechanics can yield mathematical models with enhanced accuracy. This new friction model more accurately captures the true behavior of an elastic belt that exhibits microslip prior to fully-developed slip than previous regularized friction models. The Elastic/Perfectly-Plastic friction model was applied to a two-pulley flat belt system, and the equations of motions were derived using Hamilton's Principle. The results from the analytical model were compared to results from a finite element model. It was found that, unlike Coulomb's Law, the solutions with the EPP model had no slope discontinuities in the normal force. The elimination of these slope discontinuities could potentially help alleviate convergence issues for more complex models. It was also found that if the EPP spring stiffness is too small, then the belt cannot undergo the prescribed tension change. If it is too large, then the EPP model approaches Coulomb's Law and sharp changes appear. The Elastic/Perfectly-Plastic friction model was also applied to a v-belt model. It was found that the solutions and convergence properties with the EPP friction model were similar to the solutions with the Coulomb friction model. When compared to Coulomb's Law, the range of possible high tensions for a given low tension was reduced slightly for the EPP friction. Convergence fails due to sharp changes of the inclination angle and the sliding angle. Because the sharp changes occur when the belt exits the pulley, the EPP friction model cannot smooth the slope discontinuities.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 181-192).

Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Streator, Jeffrey; Committee Member: Blanchet, Thierry; Committee Member: Cowan, Richard; Committee Member: Danyluk, Steven; Committee Member: Neu, Richard; Committee Member: Thadhani, Naresh. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2007. / Committee Chair: Itzhak Green; Committee Member; Jeffrey Streator; Committee Member: Richard Neu. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Includes bibliographical references (p. 227-233).

Foram realizados ensaios tribológicos do tipo pino-disco com pinos de cobre puro, alumínio e latão para sob cargas normais de 10, 20 e 50 N contra discos de aço, que foram analisados após os ensaios utilizando interferometria óptica 3D e microscopia eletrônica de varredura. O par tribológico cobre-aço apresentou curva de coeficiente de atrito instável, com valor médio de 0,65. Os pares alumínio-aço e latão-aço apresentaram curvas de coeficiente de atrito mais estáveis que aquelas apresentadas nos ensaios com pinos de cobre, com valor médio de coeficiente de atrito de 0,42 e 0,30, respectivamente. Tanto nos discos ensaiados com pinos de cobre quanto nos pinos ensaiados com pinos de alumínio observou-se a formação de filmes ricos em oxigênio. A formação de ilhas de cobre metálico provocou a instabilidade do comportamento do coeficiente de atrito do par cobre-aço, enquanto que o par alumínio-aço teve um comportamento mais estável devido as ilhas de óxido de alumínio. Nos ensaios utilizando pinos de latão, por sua vez, a presença de chumbo e oxidação moderada da superfície foi responsável pelo menor e mais estável coeficiente de atrito dos três pares tribológicos. O aumento da carga normal não alterou o comportamento do coeficiente de atrito, porém teve influência na formação das camadas de material aderido do pino na superfície dos discos. / Pin on disc tribotests were performed with copper, brass and aluminium pins tested against steel discs under normal loads between 10 and 50 N and characterized by means of laser interferometry and SEM. Copper-steel tribotests showed an unstable coefficient of friction curve around 0.65. Aluminium-steel and brass-steel tribopairs featured stable coefficient of friction curves, around 0.42 and 0.30, respectively. Both copper-steel and aluminiumsteel pairs presented oxygen rich transfer films. An adhesion of metallic copper patches caused the unstable coefficient of friction for the copper-steel, whereas for the aluminium-steel tribopair, the oxide layer controlled the coefficient of friction behaviour. An oxygen rich layer with some lead controlled the coefficient of friction for the brass-steel tribopair. Increasing the normal load did not affect the coefficient of friction but affect the formation of transfer layers.