Damage analysis of sheet metal forming for IF steel

Abstract

Hill’s quadratic yield criterion and flow theory is employed to describe anisotropic plasticity of sheet metal during forming procedure. Based on Continuum Damage Mechanics, an isotropic damage model is developed to give a damage-coupled localized necking criterion. Experiments of formality of sheet metal in three plane states are performed on IF steel. By measuring the density, the damage curves obtained are compared with calculation results based on the damage-coupled model, which shows a good coincidence. Furthermore, for the uniaxial and biaxial tension states, the relations between the damage of density and strain in thickness are analyzed, which helps to discuss the forming mechanism of IF steel sheet metal.