Study on the wrinkling of bulged AA 5052 alloy sheet metal during restoration

In this work, a study on the wrinkling of bulged samples of AA 5052 alloy sheets was conducted during a restoration process. Before bulging, the samples were annealed at different temperatures, i.e., at 150 °C, 200 °C, 250 °C and 300 °C. These annealed samples were then subjected to biaxial stretching (bulging) and were then compressed in between two platens. During compression (restoration), the sheet metals exhibited concentric circles of wrinkles. The aim of this research was to determine the material parameters that suppress these wrinkles. The Sheet metals that were annealed at a higher temperature exhibited a better resistance against wrinkling, because of a higher n-value, a higher R-value and a lower yield stress.