CONTACT ANALYSIS OF ROUGH SURFACES UNDER TRANSITION CONDITIONS IN SLIDING LINE LUBRICATION

This experiment investigated the transitional lubrication mechanism of fully submerged sliding line contacts under continuous operating cond itions. Transition curves with three average roughness values were est ablished. This experiment illustrates the effects of sliding speed, sp ecific load, and roughness value on transition behavior by means of a microcontact model. Except for the inflection point on the first trans ition curve, the results show that (A(t))(II) > (A(t))(I) greater than or equal to (A(t))(III), (A(p))(II) > (A(p))(I) > (A(p))(III), and (A (p)/A(t))(III) > (A(p)/A(t))(I) > (A(p)/A(t))(II). The deviation of th e first transition and second transition points is most notable due to the low sliding speed and the low roughness value. However, in this e xperiment, the greater part of the total contact area exhibits plastic deformation at transition points whether the general plasticity index is low or high (0.79-3.79) as the average roughness value is from 0.2 mu m to 1.1 mu m. Three contact areas (A(t), A(p), A(c)) at three tra nsition points decrease when the sliding speed or roughness value incr eases, while the general plasticity index (Psi) has the opposite tende ncy. The A(p)/A(t) decrease with increases in the sliding speed or dec reases in the roughness value. The values of the friction coefficient recordings under continuous operating conditions can be summarized as: f(RI) < 0.1, 0.035 < f(RII) < 0.25,f(I) >f(RII),f(I) >f(RI), and f(RI I) >f(RII). The general plasticity index decreases gradually from boun dary lubrication to scuffing failure (Psi(I) > Psi(II)) for all roughn ess values and sliding speeds. As a result, it can not be considered a s a single indicator for the second transition. (C) 1998 Elsevier Scie nce S.A. All rights reserved.