A Constitutive Friction Law for Sheet-Bulk Metal Forming

Friction has a significant effect on metal forming both in economic and technical terms. This is especially true for sheet-bulk metal forming, which is a combination of bulk metal forming and sheet metal forming. Contact loads of sheet forming processes are typically low to moderate. In contrast, very high contact loads occur in bulk metal forming. Therefore, a friction law, which is applicable for a broad range of contact loads, is necessary, if such a process has to be modelled accurately with the finite element method. A friction law fulfilling this demand is identified with the use of an elastic-plastic half-space model. The half-space model is used to determine the normal contact of rough surfaces and it is validated with experiments. In order to highlight the impact of the identified friction law, a typical sheet-bulk metal forming process is taken into account in the framework of the finite element method