Finite element analysis of limit strains in biaxial stretching of sheet metals allowing for ductile fracture

To predict limit strains in biaxial stretching of sheet metals, a criterion for ductile fracture is combined with the finite element simulation. The l imit strains are determined by substituting the values of stress and strain obtained from the finite element simulation into the ductile fracture crit erion. Material constants in the criterion are obtained from the fracture s trains measured in the biaxial stretching tests. Calculations are carried o ut for various strain paths from balanced biaxial stretching to uniaxial te nsion of aluminium alloy sheets, and compared with the experimental results . The predicted limit strains are in good agreement with the measured ones not only just at the fracture site but also at outside of the fracture site . It is demonstrated that the forming limit diagrams are successfully predi cted by the present approach. (C) 2000 Elsevier Science Ltd, All rights res erved.