A multi-scale friction model framework for full scale sheet forming simulations

In this paper a numerical framework is proposed which accounts for the most important friction mechanisms. Static flattening and flattening due to bulk strain are accounted for by theoretical models on a microscale. Based on statistical parameters a fast and efficient translation from micro- to macro modeling is included. A general overview of the friction model is presented and the translation from micro to macro modeling is outlined. The development of real area of contact is described by the flattening models and the effect of ploughing and adhesion on the coefficient of friction is described by a micro-scale friction model. A brief theoretical background of these models is given. The flattening models are validated by means of FE simulations on microscale and the feasibility of the advanced macroscopic friction model is proven by a full scale sheet metal forming simulation