MULTISCALE FRICTION MODELING FOR SHEET METAL FORMING Authors

The most often used friction model for sheet metal forming simulations is the relative simple Coulomb friction model. This paper presents a more advanced friction model for large scale forming simulations based on the surface change on the micro-scale. The surface texture of a material changes if two surfaces are in contact under a normal load which is an effect of flattening due to normal loading and flattening due to stretching. Shear stresses between the contacting surfaces, developed by adhesion and ploughing effects between contacting asperities, will change if the surface texture change. A numerical procedure has been developed which accounts for the change of the surface texture on the micro-scale and its influence on the friction behavior on the macro-scale. The numerical procedure is implemented in a finite element code and applied to a full scale sheet metal forming simulation.