Tribological Size Effects in Sheet Metal Forming Measured by a Strip Drawing Test

The aim of this work is to identify the tribological size effects within sheet metal forming and to develop a size-dependent friction function for the integration in the FEM-simulation. A strip drawing test with deflection in combination with a numerical identification is used. The numerical identification is based on an analytical model for the punch force and an optimisation program, which identifies the friction coefficient in dependence on the contact pressure from the measured punch force vs. punch travel. Scaled experiments with sheet thicknesses from 0.02 mm to 2 mm were done to identify the tribological size effects.