Abstract
Restoration tests were carried out using specimens bulged to different heights and diameters. The diameters use an Erichsen test device and a specially fabricated bulging die. Soft aluminum (Al–O) sheets were used as test specimens. The bulged sheets were compressed in the upper and lower plates of the material testing machine. The thickness of the specimens was changed from 0.4 to 2 mm. And the effect of thickness on the restoration behavior of the bulged specimens was investigated. The results of the experiments showed that some circular wrinkle patterns appeared on the sheet surface due to buckling at the bulged portion during compression when the bulged specimen was compressed to a flat sheet. Some restoration patterns were observed depending on the thickness of the material. The number of wrinkles formed after restoration was influenced by the thickness of the material, the height of the bulge and its diameter.
