A New Methodology for Determining the Friction Factor

The friction law, which requires that the friction stress is a constant fraction of the local yield shear stress, is widely used for modeling bulk metal forming processes. Determining the friction factor involved in this friction law requires an experiment and its theoretical description. It is advantageous if the latter is not based on the finite element or similar methods, since the friction factor is unknown prior to the calculation. The present paper suggests using a plane strain compression test. The experimental setup is slightly more complicated than the standard ring compression test. However, its advantage lies in the availability of relatively simple and accurate theoretical solutions for a broad class of constitutive equations, which overcomes the experimental disadvantage. The present paper is limited to isotropic strain-hardening materials. The experimental research is conducted on aluminum alloy AA 6026 and steel C45. The friction factor is determined for three types of lubricant.