FricON – Advanced friction consideration in sheet metal forming simulation

FricON – Advanced friction consideration in sheet metal forming simulation

 

Motivation

The role of numerical simulation in metal forming gained in importance over the recent years. Although many processes can be approximated very well, by now the field of friction-consideration in the deep drawing simulation is not fully explored. Nowadays a constant coefficient of friction in the forming simulation is assumed by default. This assumption is a simplification. In the real forming process, the coefficient of friction changes during the simulation depending on different factors (contact normal stress, relative speed, strain path…). A numerical model, which is able to reflect the real conditions of the forming process, represents a significant improvement of the state of the art.

[1] Rectangular cup with marked stress-bearing areas
[1] Rectangular cup with marked stress-bearing areas
[2] Forming limit diagram (FLD) of a rectangular cup including the strain paths
[2] Forming limit diagram (FLD) of a rectangular cup including the strain paths

Aim

In a previous project pre-stretched samples have been analyzed to determine the local friction coefficient of a real component. A qualitative mapping of the friction coefficients for the strains according to the characteristic Forming limit diagram was not performed. The goal of this project is to generate a database in which the friction coefficients of defined preloads are accumulated. The created database should indicate if the whole area of the forming process within the FLC can be predicted by the determination of certain friction coefficients for defined strains (Figure [2]). The generated data will be subsequently implemented in a friction model compiled to the software PAM-STAMP in order to improve the quality of the simulated deep drawing results.

Methodical approach

Preloads which arise as a result of the deep drawing process are to be initially determined numerically. Subsequently, these strain paths are replicated in an experiment and the coefficients of friction are determined by the PtU-owned strip draw test. The completion of the project is a comparison of the conventional simulation results with the results generated by the new friction model.

 

Acknowledgment

This project (HA project no. 398/13-37)is funded in the framework of Hessen Modell Projekte, financed with funds of LOEWE – Landes-Offensive zur Entwicklung Wissenschaftlich-ökonomischer Exzellenz, Förderlinie 3: KMU-Verbundvorhaben (State Offensive for the Development of Scientific and Economic Excellence).