Determination of a Constitutive Friction Law Using an Elastic‐Plastic Half‐Space Model

Friction influences metal forming processes both in economic and technical terms. A precise understanding of friction is inevitable as friction restricts the potential of the product design. Friction depends on the occurring contact loads which is especially true for sheet‐bulk metal forming (SBMF) as the incorporated contact loads appear in a very broad range. Numerical simulations, which are verified experimentally, are carried out to analyse contact interactions which typically appear in SBMF. On the one hand the multi‐scale character of rough surfaces requires a very fine resolution of the contact area, on the other hand a large contact area is necessary to be representative. A half‐space model is chosen for the contact analysis, because it only depends on the two‐dimensional surface boundary which consumes less computing capacity than the finite element method (FEM) with its three‐dimensional volume approach for the same surface resolution and area. The outcome is a constitutive friction law (CFL) consisting of two equations. The law is implemented into the framework of FEM to see the impact in a typical SBMF‐process which aims to form metal sheet into cups with integrated gearing teeth. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)