Showing papers on "Lubrication theory published in 1971"

An Isothermal Hydrodynamic Lubrication Theory for Hydrostatic Extrusion and Drawing Processes With Conical Dies

Abstract: R. W. Snidle, D. Dowson, and B. Parsons. The authors have carried out a straightforward plastohydrodynamic analysis of the hydrostatic extrusion process under isothermal conditions and have obtained an expression for the nondimensional extrusion pressure in terms of the geometry of the process, the state of augmentation, and the pressure coefficient of viscosity of the lubricant. They have assumed that deformation occurs homogeneously and that the workpiece is characterized by a constant value of the yield stress. For these conditions the total value of the extrusion pressure may therefore be considered to be made up of two components. The first component is simply the pressure required to perform the ideal, homogeneous deformation and is given by

Damping characteristics of a liquid squeeze film.

Abstract: Consideration of the damping characteristics of a liquid film located between two nearly parallel plane surfaces in relative normal motion which are always closely spaced compared to the dimensions describing the area of the two like surfaces. It was found that if the motion is slow enough (about 3 centipoise or less), the fluid inertia can be neglected and the resulting fluid flow conforms to Reynold's lubrication theory. Experiments were also carried out to determine how the damping factor of a liquid squeeze film varies with film viscosity, film thickness, amplitude, and frequency under free vibration of a single-degree-of-freedom system. The data are compared to computer solutions of the nonlinear differential equation of motion. With other variables held constant, the damping factor was found to decrease as the plate spacing is increased, decrease as the viscosity is decreased, and increase as the initial spacing is decreased.