Experimental and numerical study of microstructure, mechanical characteristics, and forming limit curve for Al 1050/ Mg-AZ31B two-layer sheets manufactured via roll bonding technique

Abstract

In this article, Al 1050/ Mg-AZ31B two-layer sheets were fabricated by the roll bonding technique. Then, forming limit diagrams and mechanical characteristics were studied experimentally and numerically. Interface modeling by applying the traction-separation rule, and cohesive zone model (CZM) was performed to improve the accuracy of finite element simulations for the first time. First, the interface behavior of the bilayer sheets was investigated experimentally by determining peeling strength and shear strength. Then, the theoretical relation was used to determine the fracture toughness in the normal and shear directions. The cohesive zone model was based on the surface and applying traction–separation rule. Finally, the tensile strength and forming limit curve were simulated for the Al/Mg composite sheet via LS-DYNA R6.1 software. The obtained results showed that the cohesive zone model could accurately predict the mechanical characteristics and forming limit diagram of the Al/Mg laminated composite so that the errors in ultimate tensile strength, strain at the delamination, and fracture strain are 2%, 7%, and 6.7%, respectively. The maximum discrepancy in comparison between the experimental and numeral results is 6.67% in all of the limit strains in the Nakazima test.