Non-Uniform Pressure Distribution in Draw-Bend Friction Test and a New Methodology to Determine Non-Constant Friction Coefficient From the Test

Friction under lubricated conditions is known to depend on pressure, and experimental determination of this dependence has typically quantified pressure as an average value over the contact area. However, non-uniform pressure distributions at the contact interfaces of draw-bend tests have been reported from various experiments and simulations. A previous study by the authors has evaluated the current methodology, which assumes uniform pressure distribution to estimate friction coefficients from draw-bend friction tests, and has concluded that the current methodology is only valid for measuring an average friction coefficient over the pressure range, which exists in the specific draw-bend system. In this paper, a new methodology to extract non-constant friction coefficients from draw-bend friction tests is suggested. In the methodology, contact pressure maps obtained from simulations, instead of the uniform pressure assumption, are included in the analysis of test data to measure the pressure dependency of friction coefficient. The methodology is tested by applying the method to back predict the input friction data from finite element simulation results of draw-bend friction tests, in which non-constant friction models are used as friction input.Copyright © 2006 by ASME