Numerical Simulation of Stamping and Hemming for Aluminum Alloy Automotive Hood Assembly

Abstract

Aluminum alloys have been increasingly applied to automotive closures and body-in-white, such as hoods, to achieve lightweight. The automotive hood assembly consists of inner and outer panels, and its manufacturing processes involve stamping and hemming. The complex manufacturing processes cause aluminum alloy sheets to undergo intricate strain paths and hardening behaviors, presenting challenges in the precise forming simulation of aluminum alloy automotive hood assembly. In this study, the advanced constitutive model, which includes the BBC2005 yield locus and the Yoshida-Uemori(Y-U) kinematic hardening model that incorporates elastic modulus degradation, was calibrated and used to establish an accurate forming simulation of an aluminum alloy automotive hood assembly. Uniaxial and biaxial tensile tests were carried out to calibrate the yield locus. Additionally, tension-compression tests were performed to capture the hardening behavior of aluminum alloy sheets under reverse loading paths, particularly the Bauschinger effect. Compared to other constitutive models, e.g. isotropic hardening model and Barlat-Lian89 yield locus, the advanced constitutive model improved the simulation accuracy by 16.7% for the outer panel, 31.5% for the inner panel, and 11.4% for the whole assembly. The results demonstrate that the advanced constitutive model is capable of capturing intricate strain paths and hardening behaviors of aluminum alloy sheets in manufacturing processes of automotive hood assembly, and also improves the accuracy of springback prediction under complex loading paths.