Development of a Friction Approach for the FE Method of Sheet Metal Forming Based on Surface Topography Evolution - Study considering Aluminum AlMg3

Autor: Barbara Homann

ISBN: 978-3-95900-028-4

Dissertation, Leibniz Universität Hannover, 2015

Herausgeber der Reihe: Bernd-Arno Behrens

Band-Nr.: IFUM 4/2015

Umfang: 108 Seiten, 61 Abbildungen

Schlagworte: Sheet metal forming, friction, anisotropy, FEA

Kurzfassung: In this thesis, a new approach improving friction modeling in the FEA of sheet metal forming processes was developed on an example of aluminum alloy AlMg3. This approach takes into account the surface topography evolution and its influence on the coefficient of friction.
To analyze the surface topography due to deep drawing conditions, basic experiments were carried out. The surface topography was analyzed by means of roughness measurements before and after forming. The influence of process parameters on the surface roughness of the sheet was determined. A strong anisotropic roughness evolution was found out, depending on the direction of motion as well as on the direction of the roughness measurement. Furthermore, the influence of the change in surface roughness and of the determined parameters on the coefficient of friction was determined.
Finally, the mathematical descriptions were implemented in the FEM software LS-DYNA by a user-defined subroutine usrfrc. Thus a new friction approach was realized.