Multiphase hydrodynamic lubrication flow using a three-dimensional shell finite element model

Multiphase hydrodynamic lubrication flow using a three-dimensional shell finite element method.

Large-scale, high-throughput production of nano-structured materials (i.e. nanomanufacturing) is a strategic area in manufacturing, with markets projected to exceed $1T by 2015. Nanomanufacturing is still in its infancy; process/product developments are costly and only touch on potential opportunities enabled by growing nanoscience discoveries. The greatest promise for high-volume manufacturing lies in age-old coating and imprinting operations. For materials with tailored nm-scale structure, imprinting/embossing must be achieved at high speeds (roll-to-roll) and/or over large areas (batch operation) with feature sizes less than 100 nm. Dispersion coatings with nanoparticles can also tailor structure through self- or directed-assembly. Layering films structured with these processes have tremendous potential for efficient manufacturing of microelectronics, photovoltaics and other topical nano-structured devices. This project is designed to perform the requisite R and D to bring Sandia's technology base in computational mechanics to bear on this scale-up problem. Project focus is enforced by addressing a promising imprinting process currently being commercialized.

/pdf/nanomanufacturing-nano-structured-materials-made-layer-by-3noaioi5nr.pdf

Nanomanufacturing : nano-structured materials made layer-by-layer.

Wear tests are often used in engine development in order to characterize the functional profile of surfaces interacting with lubricants. This paper proposes a new test procedure to determine Stribeck-type curves for the tribosystem piston ring/cylinder liner involving test pieces prepared from engine components. The variation of the friction coefficient with sliding speed depends on the structure and constitution of the base oil, the viscosity index, the surface topography of the liner and ring, and the friction modifiers used. Novel organic friction modifiers of low molecular mass not only reduce the friction coefficients under mixed / boundary lubrication, but also in the fluid film regime. In addition, the influence of surface roughness on the wettability of surfaces can be significant for both static and dynamic wetting. For this reason, the interaction of the lubricant with the surfaces was also investigated to enable a correlation between the surface properties of the liquid and solid phases and the tribological behavior.

Stribeck-Type Curves of Alternative Engine Oils: Part I: Gray Cast Iron Liners

On the basis of the micro continuum theory, a theoretical analysis of the effects of pressure distribution using couple stress on the squeeze film behavior of parabolic inclined slider bearing is presented. The modified Reynolds equation governing the squeeze film pressure is derived by using the stokes constitutive equation and the analysis taking into account the squeezing effect with no slip at the porous interface comparing with the traditional Newtonian lubricant case, the effects of couple stress characteristics by the couple stress parameter signify an improvement in the steady state performance. We are considering the parabolic inclined bearing to analyze the effect of pressure and compared to the inclined plane bearing, step inclined bearing, the parabolic shaped slider bearing lubricated with couple stress fluids results in a higher pressure distribution. The performances are emphasized especially for the bearing with smaller film heights. AMS Subject Classification: 76B99, 76M15, 76M25, 76N99, 76S05

/pdf/squeeze-film-characteristics-and-steady-state-performance-of-3dtoj1n34u.pdf

Squeeze film characteristics and steady state performance of a parabolic inclined porous slider bearings using couple stress fluid

Publisher Summary This chapter focuses on the load capacity of the conventional, liquid-lubricated, journal bearing benefits from the close conformity between two surfaces. Common forms of thrust bearing have films of similar proportions. This is not applicable for gear tooth engagements, cams and followers, and nor for the contact between rolling elements and raceways in rolling contact bearings. In these, the contact areas are small and high interfacial pressures must be generated with or without a liquid lubricant. Such arrangements frequently operate without significant metallic contact despite pressures of the order of 10 4 atmospheres. These are considered to be elastohydrodynamically lubricated, such that the shape of the high modulus elastic boundaries to the conjunction becomes modified by virtue of the hydrodynamic pressures generated. A concentrated line load applied to the boundary of a semi-infinite elastic body in elasticity theory yields surface displacements which go to infinity under the load line.

Elastohydrodynamic Lubrication Theory

Publisher Summary This chapter discusses the basic concepts of viscous flow and develops the governing equation of fluid film lubrication, the “Reynolds equation.” It presents a model for various operating parameters bearing specifically the “narrow journal bearing theory.” An ideally elastic material obeys the Hooke's law—that is, under stress an equilibrium strain develops, the two being proportional to one another. The plain journal bearings associated with reciprocating internal combustion engines tend to be narrow in relation to their diameters. The bearing's load capacity may be estimated from an integration routine. The mean temperature rise in the fluid expelled from a bearing provides a reliable means of estimating the effective temperature of the fluid within the film, of its viscosity, and of the viscous friction in the bearing.

D.A. Jones

Papers

Elastohydrodynamic Lubrication Theory

Short Journal Bearing Lubrication Theory