Numerical Analysis of Single Point Incremental Forming of AA5754-O Sheet Using Combined Isotropic/Kinematic Hardening Model

Single point incremental forming (SPIF) is a flexible process for manufacturing various intricate sheet metal components. The improved formability in this process is one of its distinctive features that has attracted the researchers interest. This paper presents an investigation of the process through a numerical scheme that reveals the proper hardening behavior of AA5754-O sheet metal during the deformation. So, an elasto-plastic constitutive model with isotropic hardening and combined isotropic/kinematic hardening model are adopted to simulate the SPIF process. Also, to predict the fracture behavior of sheet metal, Brozzo phenomenological model is used. A series of uniaxial tensile tests were performed to extract AA5754-O sheet metal constants, and also SPIF experiments were performed to investigate the process. A user-defined material subroutine (VUMAT) is employed to implement the material behavior of the sheet metal. Numerical and experimental results in terms of deformed shape and thickness evolution are compared to present the efficiency of the finite element model and interpret the process. Results show that combined isotropic/kinematic hardening predicts better the deformation of sheet metal during the SPIF process and give a more exact prediction of the shape of the deformed geometry. In addition, the strain distribution of the deformed geometry in the forming limit diagram space is plotted, which indicates the higher forming strains of the SPIF process.