Stress of material in the area of stretching ([[epsilon].sub.2] > 0) was modelled by Erichsen test. Stretchability is expressed as IE height of cup.
Technological characteristics obtained by Erichsen test and cup test as well as these values calculated for selected materials by numerical simulation are shown in Table 3.
The numerical simulation of Erichsen test and cup test for selected materials were realised in order to compare experimental and calculated values.
Another method to determine the formability of the steel sheet uses deep drawing applications is the Erichsen test
(Garcia et al., 2008).
A high value of the hardening coefficient indicates that the material supports a maximum uniform deformation, and the maximum local deformations are lower due to the deformation process that appears during the Erichsen test.
The limits of the parameters obtained after tensile tests and the Erichsen tests are presented in Table 1.
According to Ciba, Irgasurf SR 100 can impart scratch performance up to 15 Newtons in the "five-finger" and the cross-cut Erichsen tests
used by many automotive producers.