Formability Analysis of Aluminum-Aluminum and AA5182/Polypropylene/AA5182 Laminates

Owing to their weight saving potential and improved flexural stiffness, metal-polymer-metal sandwich laminates are finding increasing applications in recent years. Increased use of such laminates for automotive body panels and structures requires not only a better understanding of their mechanical behavior, but also their formability characteristics. This study focuses on the formability of a metal–polymer-metal sandwich laminate that consists of AA5182 aluminum alloy as the outer skin layers and polypropylene (PP) as the inner core. The forming limit curves of Al/PP/Al sandwich laminates are determined using finite element simulations of Nakazima test specimens. The numerical model is validated by comparing the simulated results with published experimental results. Strain paths for different specimen widths are recorded. The variation of the forming limit curves with different thickness combinations of the outer skins and inner layer is determined to understand the effect of skin-to-core thickness ratio on the formability. Additionally, a comparison of the sandwich laminates with single aluminum sheets and aluminum-aluminum laminates of equivalent thickness is made to understand the advantage of the presence of the polymer core on the limit strains. Investigations are also made on layered aluminum laminates with varying friction between the two sheets to gain insight on the advantage of the presence of bonding between the layers in Al/Al laminates.