Development of a friction model for the numerical simulation of clinching processes

In the numerical simulation of mechanical joining processes, such as clinching, modeling material behavior is of decisive importance. In addition to the correct representation of, e.g., plasticity and damage mechanisms, this includes primarily modeling the friction behavior between the parts to be joined. This paper presents a method for the experimental characterization and numerical modelling of the frictional behavior within mechanical joining processes like clinching. An axial torsion test was used to generate surface conditions on technological specimens that also occur in the joined parts during the clinching process. It also enables the decoupled investigation of friction-relevant parameters, such as relative velocity or contact pressure. The experimentally generated data sets using aluminum material have been transferred into an analytical approach. Combined with a modifiable user subroutine, it has been implemented into the FE modeling using LS-Dyna. Validation was performed by numerically modeling the axial torsion test and comparing experimental and numerical results. Finally, the clinching process is calculated with the developed friction model and a standard friction model, and the results are compared.