Viscoplastic Lubrication of Asperities

Abstract

Theoretical analyses for the lubrication of rigid wedge-shaped asperities by a viscoplastic liquid are developed. Two cases are considered in which wedge action and squeeze action are dominant. The results of the analyses are compared with previous experimental investigations of the factors influencing susceptibility to lubrication failure.

Viscoplastic Behavior of a Silicone Oil in a Metalforming Inlet Zone

“…These conditions may be found in metal forming processes such as drawing and extrusion which involve sliding contact. They are also highly likely to occur in the interactions between surface asperities in many types of lubricated contact [8,13].…”

“…Figure 1 shows the relationship between the lubricant shear stress and shear strain rate, and the resulting relationship between pressure gradient and flow used in the analysis. These are the same as those developed by Wilson and Aggarwal [6] and used by Sheu and Wilson [8]. Figure 1(a) shows the assumed constitutive behavior of the lubricant.…”

“…Using these variables, and with h from equation (12) or (13), equations (6), (7), (8), and (9) can be rewritten, respectively, as It is more convenient to work in dimensional form in comparing theory and experiment. Thus the inlet film thickness h 0 was also calculated for various values of the lubricant properties ix 0 , k 0 , 7, and m, the workpiece flow strength a, roll speed U, inlet angle 6, roll radius a and inlet strip thickness y x .…”

Surface modification of polymers: Physical, chemical, mechanical and biological methods

“…Attachment of PEO to surfaces has been one of the most extensively studied treatments. (8)(9)(10)(11)(12)(13) If the molecular weight of the PEO is above -500-1,000 (lo), the surface will resist protein adsorption and cell adhesion. Such a surface has been called "non-fouling."…”

“…A new method for immobilizing a PEO surfactant by crosslinking its hydrophobic "tail" to polymer surface groups in an argon RFGD has been applied to a number of different surfactant compounds, in order to functionalize hydrophobic surfaces. (12,13) Table 7 lists some of the compositions which have been immobilized by this process.…”