tailieunhanh - Friction and Lubrication in Mechanical Design Episode 2 Part 1

Tham khảo tài liệu 'friction and lubrication in mechanical design episode 2 part 1', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 230 Chapter 6 line XX at F . A horizontal line F G is then drawn to meet the line p 500 at G . The point H vertically above G gives the first approximation for s to be . This value of 5 is then entered as point in the second nomogram Fig. . Draw a vertical line IJ to meet the curve LỊD 1. Then the horizontal line JK meets RCL k line at K. Point L is vertically below point K and on the line b6 T Ớ 2 . The horizontal line LMN is such that point N is vertically below point I and point M is on the p aw axis. Point M provides the new approximation for p 495 psi and point N gives AT a 110 F for L D 1 . With AT 110 F the new entry point A2 in the first nomogram Fig. is determined and the procedure is continued. After six iterations s can be accepted as the solution for the considered example. THERMOHYDRODYNAMIC LUBRICATION ANALYSIS INCORPORATING THERMAL EXPANSION ACROSS THE FILM Viscosity is generally considered to be the single most important property of lubricants therefore it represents the central parameter in all lubricant analysis. By far the easiest approach to the question of viscosity variation within a fluid film bearing is to adopt a representative or mean value viscosity. Examples of studies which have provided many suggestions for calculations of the effective viscosity in a bearing analysis are presented By Cameron 34 and Szeri 35 . When the temperature rise of the lubricant across the bearing is small bearing performance calculations are customarily based on the classical isoviscous theory. In other cases where the temperature rise across the bearing is significant the classical theory loses its usefulness for performance prediction. One of the early applications of the energy equation to hydrodynamic lubrication was made by Cope 36 in 1948. His model was based on the assumptions of negligible temperature variation across the film and negligible heat conduction within the lubrication film as well as into the adjacent .