Modeling the frictional boundary conditions in a rolling process

Abstract

In order to model the frictional boundary conditions in a rolling process, a combined friction model, which is based on the concept of dividing the zone of friction at the contact zone, is presented. In the combined friction model, the frictional stress is expressed as the product of an exponential velocity-dependent expression and a conventional friction expression. The distributions of the frictional stress, the normal stress, the relative velocity, and the dynamic coefficient of friction along the are of contact are calculated using a developed rigid-plastic finite-element code under different conventional friction models, combined with the exponential expression. The effect of the relative velocity factor in the exponential expression is discussed. The roles of the four conventional friction models, i.e., the Wanheim-Bay, the Coulomb, the Stephenson and the constant-friction models, are evaluated and compared. It is shown from numerical calculations that the combined friction model of the Wanheim-Bay friction expression and the exponential velocity dependent expression is satisfactory.