Application of an Advanced Friction Model in Hot Stamping Simulations: A Numerical and Experimental Investigation of an A-Pillar Reinforcement Panel from Volvo Cars

Abstract

Although hot stamping is now an established method, numerical analysis of the process is still a challenge. In industrial applications, process engineers use sophisticated models which consider complex physical effects including phase transformation, phase dependent flow curves, temperature dependent r-values and temperature dependent FLC’s. However, in most of the industrial applications the tribological system is still oversimplified by using a constant Coulomb friction coefficient. Currently, there is enough experimental evidence in literature showing that friction coefficients evolve during the process, depending on contact pressure, temperature and sliding velocity. This work focuses on accurate modelling of friction in hot stamping processes. The advanced modelling technique presented in this paper tracks each material point and calculates the corresponding coefficient of friction depending on the current process conditions. This technique was used on simple part geometries in order to generate fundamental knowledge. In this analysis, part geometry, process conditions and tool kinematics are varied. In the next step, an A-Pillar reinforcement panel from Volvo Cars was analyzed experimentally and numerically. It was seen that accurate friction modelling enhances the quality of the simulation results and evolving friction conditions have a direct effect on the feasibility analysis of industrial parts.