The study is concerned with the analysis of stretch-forming of sheet metal by matrix method, which incorporates effect of friction, normal anisotropy, and work-hardening. The frictional coefficient measured from the experiment is used directly for the stress boundary condition of matrix method formulation. The frictional coefficient (μ) is measured by newly developed device which simulates the stretching under plastic deformation.
Experiments are carried out with cold-rolled steel sheet under various frictional conditions by changing the lubricants under the hemispherical punch. The forming load is measured by the built-in load cell in the punch and the strains are measured from the photo-gridded specimens.
It is shown that the experiments are in excellent agreement with the theoretical predictions by matrix method both in forming loads and in strain distributions.