Introduction

In modelling metal forming processes, whether analytically or with the help of numerical approaches, e.g. the finite element method (FEM), the input data determines the results. Therefore, a lot of effort is put into the acquisition of quantitative modelling data [PHI 93]. The measurement of the stress-strain-curves of metals is one of the important tasks. In conventional metal forming processes, up to strain rates of 300 sec ^?1 a lot of data can be accessed through various sources. The acquisition of stress-strain properties relevant to the metal cutting processes is still in its research state. Thermal bulk properties of materials can be measured exactly as well and are accessible.

The properties of the contact, however, are far less understood and less data is available. This applies to thermal problems where the heat transfer between contacting bodies is strongly dependent on contact pressure as well as on the properties of the surfaces.

This applies even more, however, to the mechanical side of the contact. The solution of the variational problem of metal flow, that can be solved using the finite element method, as well as analytical approaches, take the frictional forces into consideration. The FEM can incorporate quite sophisticated formulations of the dependency of the friction stresses on surface or bulk material properties [KOB89]. In most cases, however, Coulomb's friction law or the law of constant shear serve as a basis for the implementation. This is mainly due to...