FRICTION STUDIES AT DIFFERENT NORMAL PRESSURES WITH ALTERNATIVE RING-COMPRESSION TESTS

In the present paper, experimental investigations and theoretical anal yses of friction are carried out with alternative ring-compression tes ts applying three different ring geometries, namely a concave-, rectan gular- and convex-shaped ring cross-section, resulting in three differ ent normal pressures, at low, medium and high level. Aluminum alloy AA 6082 was used in the experiments, in both annealed and work-hardened c onditions. Two different lubricants were applied in the experiments, i .e. soap and molybdenum disulphide, both in connection with an alumina te conversion coating. In order to directly study the influence of fri ction whilst avoiding any coinciding influence of the strain hardening , a friction model with a constant absolute value was applied in finit e-element method (FEM) simulations for calibration of the friction. Ca libration curves with the friction constant A as a parameter were obta ined using FEM analysis and verified by the experimental results. The influence of strain hardening and pressure level on friction and metal flow are discussed. (C) 1998 Elsevier Science S.A. All rights reserve d.