3.2 Material and friction coefficient

Obtaining input data for the simulation of ISMF is not an easy task. The friction coefficients between the forming tool and the material sheet have hardly been measured and determined correctly by previous researches. Measuring forming forces and converting them into corresponding friction coefficients are also difficult. In general, the friction coefficient of the forming process could be assumed in the range from 0.05 to 0.2 depending on the specific conditions of the forming process. Another difficult issue is how to obtain reliable material data. Most studies use standard materials and conduct experiments using conventional tension or compression test methods. However, these experimental data only provide results with lower strain values than those observed during ISMF. Therefore, the representation of the stress-strain curve for higher deformation levels is necessary to simulate the ISMF process.
