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Forming limit prediction of 5182-O aluminum alloy sheet was carried out by using finite element analysis. JSTAMP/NV was used in the finite element analysis. Length of aluminum specimen was 120 mm, and the width was varied from 10 to 120 mm, and the thickness was 1.0 mm. Stretching test was operated by Erichsen test. Forming limit prediction and necking limit prediction by using finite element analysis was proposed. Forming limit diagram (FLD) of analytical results were indicated relatively good conformability with the FLD of experimental results. Also, spherical stretch forming experiments of 5182-O aluminum alloy sheet were carried out to research the formability on biaxial stress by several companies. The forming simulations were carried out using commercial software PAM-STAMP 2G. Effects of friction coefficient and yield function were investigated in the simulation. Simulation results by using YLD-2000 yield function agreed well with experimental results compared with that of Hill 48 yield function. Those were benefit for analytical simulations of sheet metal forming.

Demand of press forming of aluminum alloy sheet is increasing for improvement of fuel efficiency. FEM analysis of press forming is required to be more accurate. The objective of this study is to clarify the effect of friction coefficient on analytical accuracy in press forming FEM analysis. Spherical forming experiment and FEM analysis were performed to measure the contact pressure and sliding speed of the blank against the punch. Sliding friction test was performed to measure the friction coefficient with low pressure and low speed. The measured friction coefficient was input to the commercial FEM analysis soft PAM-STAMP2G as varied friction coefficient. The experimental thickness strain distributions were compared with the calculated results. FEM analysis results using varied friction coefficient had a better accuracy than those using constant friction coefficient.

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