Revisiting the wrinkling limit curve in sheet metal forming

The quest to minimise energy consumption in the manufacturing industry has prompted a shift towards the use of thinner sheet metals, which offer reduced energy requirements for forming operations and material usage. However, the increased susceptibility to failure, particularly by tearing and wrinkling, poses significant challenges. This study focuses on investigating the formability of aluminium AA1050-O sheets with a thickness of 1.5 mm, emphasising the determination of the onset of wrinkling, a critical parameter in sheet metal forming. Experimental tests, including the Yoshida Buckling Test, Shear Test, and Uniaxial Compression Test, were conducted to establish the onset of wrinkling under different stress states. The onset of wrinkling was determined using three different methodologies: position-dependent, physically-based, and energy-based. Notably, the authors proposed a physically-based methodology that utilises the in-plane minor strain analysis and demonstrates superior effectiveness in detecting wrinkling initiation compared to the traditional position-dependent methodology. This research provides valuable insights into enhancing the understanding and prediction of wrinkling behaviour in thin sheet metal forming processes and presents the Wrinkling Limit Curve (WLC) for the analysed aluminium sheet.